Other Supporting Document for Breast Cancer: Medications for Risk Reduction
Use of Medications to Reduce Risk for Primary Breast Cancer
A Systematic Review for the U.S. Preventive Services Task Force
Release Date: April 16, 2013
By Heidi D. Nelson, MD, MPH; M.E. Beth Smith, DO; Jessica C. Griffin, MS; and Rongwei Fu, PhD
The information in this article is intended to help clinicians, employers, policymakers, and others make informed decisions about the provision of health care services. This article is intended as a reference and not as a substitute for clinical judgment.
This article may be used, in whole or in part, as the basis for the development of clinical practice guidelines and other quality enhancement tools, or as a basis for reimbursement and coverage policies. AHRQ or U.S. Department of Health and Human Services endorsement of such derivative products may not be stated or implied.
This article was first published in Annals of Internal Medicine on April 16, 2013 (Ann Intern Med 2013;158:604-614; http://www.annals.org).
Background: Medications to reduce risk for primary breast cancer are recommended for women at increased risk; however, use is low.
Purpose: To update evidence about the effectiveness and adverse effects of medications to reduce breast cancer risk, patient use of such medications, and methods for identifying women at increased risk for breast cancer.
Data Sources: MEDLINE and Cochrane databases (through 5 December 2012), Scopus, Web of Science, clinical trial registries, and reference lists.
Study Selection: English-language randomized trials of medication effectiveness and adverse effects, observational studies of adverse effects and patient use, and diagnostic accuracy studies of risk assessment.
Data Extraction: Investigators independently extracted data on participants, study design, analysis, follow-up, and results, and a second investigator confirmed key data. Investigators independently dual-rated study quality and applicability using established criteria.
Data Synthesis: Seven good- and fair-quality trials indicated that tamoxifen and raloxifene reduced incidence of invasive breast cancer by 7 to 9 cases in 1000 women over 5 years compared with placebo. New results from STAR (Study of Tamoxifen and Raloxifene) showed that tamoxifen reduced breast cancer incidence more than raloxifene by 5 cases in 1000 women. Neither reduced breast cancer–specific or all-cause mortality rates. Both reduced the incidence of fractures, but tamoxifen increased the incidence of thromboembolic events more than raloxifene by 4 cases in 1000 women. Tamoxifen increased the incidence of endometrial cancer and cataracts compared with placebo and raloxifene. Trials provided limited and heterogeneous data on medication adherence and persistence. Many women do not take tamoxifen because of associated harms. Thirteen risk-stratification models were modest predictors of breast cancer.
Limitation: Data on mortality and adherence measures and for women who are nonwhite, are premenopausal, or have comorbid conditions were lacking.
Conclusion: Medications reduced the incidence of invasive breast cancer and fractures and increased the incidence of thromboembolic events. Tamoxifen was more effective than raloxifene but also increased the incidence of endometrial cancer and cataracts. Use is limited by adverse effects and inaccurate methods to identify candidates.
Primary Funding Source: Agency for Healthcare Research and Quality.
In 2002, the U.S. Preventive Services Task Force (USPSTF) recommended that clinicians discuss the potential benefits and harms of tamoxifen and raloxifene for reducing risk for primary breast cancer with women at high risk for breast cancer and low risk for adverse effects1, 2. The USPSTF also recommended against routine use in women at low or average risk for breast cancer.
Clinical trials demonstrate the efficacy of several medications to reduce the risk for invasive breast cancer in women without preexisting cancer3-8, but only tamoxifen citrate and raloxifene for 5 years of use are approved by the U.S. Food and Drug Administration (FDA) for this purpose9. Raloxifene is approved for postmenopausal women only. In addition to beneficial effects, these medications may cause adverse health effects7, 10, 11. In 2002, the USPSTF indicated that the risk for breast cancer within 5 years could be estimated by completing the National Cancer Institute Breast Cancer Risk Assessment Tool (Gail model). How to select patients for these medications in clinical practice has not been clear, however, and use of medications to reduce risk for breast cancer is low in the United States12.
This report is an update for the USPSTF that was derived from a comprehensive comparative effectiveness review of the efficacy, adverse effects, and subgroup variations of medications to reduce risk for primary breast cancer in women13. It also examines issues related to clinical effectiveness, such as patient choice, concordance, adherence, and persistence of use; and reviews methods to identify women at increased risk for breast cancer that are clinically applicable to determining candidacy for risk-reducing medications.
We followed a standard protocol for this review consistent with the Agency for Healthcare Research and Quality (AHRQ) Effective Health Care Program14. Key questions were developed through the Effective Health Care Program and modified for the USPSTF. Investigators created an analytic framework incorporating the key questions and outlining the patient population, interventions, and outcomes (Figure 1). The target population includes women without preexisting invasive or noninvasive breast cancer who are not known carriers of breast cancer susceptibility mutations. Interventions include FDA-approved medications to reduce risk for primary breast cancer. Health outcomes include signs, symptoms, conditions, or events as opposed to intermediate outcomes, such as laboratory test results. A technical report15 details the methods and includes search strategies and additional evidence tables.
We searched MEDLINE, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews from inception through 5 December 2012 for relevant English-language studies, systematic reviews, and meta-analyses15. We manually reviewed reference lists of articles, citations in Web of Science and Scopus, and clinical trial registries. We requested scientific information packets from manufacturers of medications. (The only packet provided was for raloxifene.)
We developed selection criteria for studies based on the patient populations, interventions, outcome measures, and types of evidence. After an initial review of citations and abstracts, we retrieved full-text articles of potentially relevant material and conducted a second review to determine inclusion. A second reviewer confirmed results of the initial reviewer, and discrepancies were resolved by team consensus. Results of the search and selection process are provided in the Appendix Figure.
Inclusion criteria for studies of benefits, harms, and subgroup outcomes (key questions 1 through 3) have been fully described in previous publications13, 15. For benefits, we included only double-blind, placebo-controlled or head-to-head, randomized, controlled trials (RCTs) of tamoxifen and raloxifene to reduce risk for breast cancer that enrolled women without preexisting breast cancer. We included trials that were designed and powered to demonstrate invasive breast cancer incidence as a primary or secondary outcome. For harms, we included RCTs and observational studies of tamoxifen and raloxifene in women without breast cancer that had a nonuser comparison group or direct comparisons between tamoxifen and raloxifene. We considered all adverse outcomes at all reported follow-up times to capture potential short- and long-term adverse effects.
We included RCTs, observational studies, and descriptive studies of decisions to use risk-reducing medications, concordance, adherence, and persistence of use (key question 4). Concordance occurs when a health care provider and patient reach a shared agreement about therapeutic goals after the patient is informed of the condition and options for treatment and becomes involved in the treatment decision16. Adherence is the extent to which a patient acts in accordance with the prescribed interval and dose of a medication17. Persistence is the duration of time from initiation to discontinuation of therapy17.
We included studies of risk-stratification models that could be used in primary care settings to identify women at higher-than-average risk for breast cancer (key question 5). Only studies reporting discriminatory accuracy were included. Discriminatory accuracy is a measure of how well the model can correctly classify persons at higher risk from those at lower risk and is measured by the model's concordance statistic or c-statistic. The c-statistic is determined by the area under the receiver-operating characteristic curve, a plot of sensitivity (true-positive rate) versus 1 – specificity (false-positive rate). Perfect discrimination is a c-statistic of 1.0, whereas a c-statistic of 0.5 would result from chance alone. An acceptable level of discrimination is between 0.70 and 0.79, excellent is between 0.80 and 0.89, and outstanding is 0.90 or greater18. We also abstracted model calibration, a measure of how well predicted probabilities agree with actual observed risk in a population. In a perfect prediction model, the predicted risk in a population would equal the observed number of cases, such that the percentage expected divided by the percentage observed equals 1.0. We excluded studies of individual risk factors or laboratory tests as well as models designed primarily to evaluate risk for deleterious BRCA mutations.
Our search strategies also included systematic reviews that addressed our key questions and had similar scope, inclusion criteria, and analytic methods for meta-analysis. Other types of analyses and statistical models were not included19.
Data Extraction and Quality Assessment
An investigator abstracted details of the patient population, study design, analysis, follow-up, and results. A second investigator confirmed key data elements. Using predefined criteria20, 2 investigators independently rated the quality of studies (good, fair, or poor) and resolved discrepancies by consensus. Investigators assessed applicability of trials using the population, intervention, comparator, outcomes, timing of outcomes measurement, and setting (PICOTS) format14.
Data Synthesis and Analysis
We updated the results of our previous meta-analysis of benefits and harms of tamoxifen and raloxifene for 2 outcomes (mortality and endometrial cancer for raloxifene) with new data using methods described in previous publications13. As a group, investigators used methods developed by the USPSTF to assess the overall quality of the body of evidence for each key question (good, fair, or poor) on the basis of the number, quality, and size of studies; consistency of results between studies; and directness of evidence20.
Role of the Funding Source
This research was funded by AHRQ. Investigators worked with AHRQ staff and a technical expert panel to define the scope, analytic framework, and key questions; resolve issues arising during the project; and review the final report to ensure that it met basic methodological standards for systematic reviews. The draft report was reviewed by content experts, USPSTF members, AHRQ program officers, and collaborative partners. The funding source had no role in the selection, critical appraisal, or synthesis of evidence. The investigators were solely responsible for the content and the decision to submit the manuscript for publication.
Benefits and Harms of Tamoxifen and Raloxifene
Seven RCTs of tamoxifen or raloxifene in women without preexisting breast cancer provide breast cancer outcomes and data about mortality and fractures. These trials also provide estimates of harm, including thromboembolic events, cardiovascular disease events, uterine abnormalities, cataracts, and other adverse effects. Additional trials and an observational study describing harms of raloxifene were identified, but these studies were small, were methodologically limited, and did not contribute data to the meta-analysis.
Trials include a head-to-head comparison of tamoxifen and raloxifene, STAR (Study of Tamoxifen and Raloxifene)21, 22; 4 placebo-controlled trials of tamoxifen, including the IBIS-I (International Breast Cancer Intervention Study)23, 24, NSABP P-1 (National Surgical Adjuvant Breast and Bowel Project)8, 11, 25, 26, Royal Marsden Hospital trial27, 28, and the Italian Tamoxifen Prevention Study29-32; and 2 placebo-controlled trials of raloxifene, MORE (Multiple Outcomes of Raloxifene Evaluation) with long-term follow-up in the CORE (Continuing Outcomes Relevant to Evista) study10, 33-46 and the RUTH (Raloxifene Use for the Heart) trial7, 47. An updated analysis of STAR with an 81-month median follow-up provided most of the new findings for this review22.
The tamoxifen trials were designed to determine breast cancer incidence as the primary outcome8, 11, 23, 24, 27-32, 48. Inclusion criteria considered breast cancer risk in all but 1 trial49. For raloxifene, breast cancer incidence was a primary outcome in RUTH and a secondary outcome in MORE. These trials were intended to evaluate the effect of raloxifene on reducing coronary heart disease events in RUTH7 and preventing fractures in MORE5, 40.
Trials varied by mean age at enrollment (47 to 50 years for the tamoxifen trials, 67 years for the raloxifene trials, and 59 years for STAR), estrogen use23, 27, 29-32, and ascertainment of outcomes. For placebo-controlled trials of tamoxifen, median duration of treatment was approximately 4 years and follow-up was 7 to 13 years8, 24. For raloxifene, results were reported after 3 and 4 years of treatment in the MORE trial26-34, 36, 39, and results of CORE (a continuation study of MORE44 were reported for 4-year and combined 8-year outcomes (MORE and CORE)37, 38, 40. The median duration of treatment in RUTH was 5.1 years41. In STAR, the mean duration of treatment was 3.8 years and median follow-up was 6.75 years22.
All trials met criteria for fair or good quality and high applicability. The trials were multicenter, were relevant to primary care, and enrolled between 247127 and 19,74748 women from clinics and communities predominantly in North America, Europe, and the United Kingdom.
In placebo-controlled trials, tamoxifen (risk ratio [RR], 0.70 [95% CI, 0.59 to 0.82]; 4 trials; 7 cases in 1000 women over 5 years)8, 24, 28, 31 and raloxifene (RR, 0.44 [CI, 0.27 to 0.71]; 2 trials; 9 cases in 1000 women)7, 44 reduced the incidence of invasive breast cancer (Appendix Table 1). In STAR, more women receiving raloxifene had breast cancer than those receiving tamoxifen (RR for raloxifene, 1.24 [CI, 1.05 to 1.47]; 5 cases in 1000 women over 5 years)22. Tamoxifen8, 24, 28, 31 and raloxifene7, 44 reduced estrogen receptor–positive but not estrogen receptor–negative or noninvasive cancer in placebo-controlled trials and had similar effects in STAR21, 22, 48. Breast cancer–specific8, 24, 28, 31, 50 and all-cause mortality rates6-8, 24, 28, 31 were not reduced in placebo trials and were similar in STAR22.
In placebo-controlled trials, raloxifene reduced incidence of vertebral fractures (RR, 0.61 [CI, 0.54 to 0.69]; 2 trials; 7 cases in 1000 women)7, 37 and tamoxifen reduced incidence of nonvertebral fractures (RR, 0.66 [CI, 0.45 to 0.98]; 1 trial; 3 cases in 1000 women)8. Tamoxifen and raloxifene had similar effects on incidence of vertebral fractures in STAR48.
Thromboembolic event incidence was increased for tamoxifen (RR, 1.93 [CI, 1.41 to 2.64]; 4 trials; 4 cases in 1000 women)11, 24, 28, 29 and raloxifene (RR, 1.60 [CI, 1.15 to 2.23]; 2 trials; 7 cases in 1000 women) compared with placebo7, 10, and raloxifene caused fewer events than tamoxifen in STAR (RR, 0.75 [CI, 0.60 to 0.93]; 4 cases in 1000 women)22. Coronary heart disease event or stroke incidence was not increased in placebo-controlled trials7, 8, 24, 28, 31, 34 and did not differ in STAR48, although women randomly assigned to raloxifene had a higher stroke mortality rate than that of those assigned to placebo in RUTH (RR, 1.49 [CI, 1.00 to 2.24])7.
Tamoxifen caused more cases of endometrial cancer (RR, 2.13 [CI, 1.36 to 3.32]; 3 trials; 4 cases in 1000 women)11, 24, 28 and was related to more benign gynecologic conditions24, 51; surgical procedures, including hysterectomy24, 28, 51; and uterine bleeding24, 51 than placebo. Raloxifene did not increase risk for endometrial cancer7, 10, 52 or uterine bleeding7, 35, 53-61. In STAR, raloxifene caused fewer cases of endometrial cancer (RR, 0.55 [CI, 0.36 to 0.83]; 5 cases in 1000 women), hyperplasia, and procedures than tamoxifen22, 62. Women receiving tamoxifen had more cataract surgeries than those receiving placebo in NSABP P-111. Raloxifene did not increase risk for cataracts or cataract surgery compared with placebo7, 10 and caused fewer cataracts than tamoxifen in STAR (RR, 0.80 [CI, 0.72 to 0.95]; 15 cases in 1000 women)22.
The most common side effects were vasomotor symptoms11, 24, 28, 31 and vaginal discharge, itching, or dryness11, 24, 28, 31 for tamoxifen and vasomotor symptoms7, 35, 55, 56, 58 and leg cramps7, 35, 58 for raloxifene. In STAR, raloxifene users reported more musculoskeletal problems, dyspareunia, and weight gain, whereas tamoxifen users had more gynecologic problems, vasomotor symptoms, leg cramps, and bladder control symptoms62, 63.
Variability of Outcomes in Population Subgroups
In STAR, tamoxifen and raloxifene had similar effects on breast cancer outcomes regardless of age and family history of breast cancer22. In NSABP P-1, cancer rates were highest and risk reduction greatest among women in the highest modified Gail model risk category (5-year risk >5%) and among women with previous atypical hyperplasia8. Additional subgroup analyses of placebo-controlled trials indicated no differences for several factors15, 43, 47. Thromboembolic events, strokes, and endometrial cancer were more common in older (>50 years) than younger women in NSABP P-18. A recent meta-analysis of tamoxifen trials indicated that risks for endometrial cancer, deep venous thrombosis, and pulmonary embolism are low for women younger than 50 years64.
Surveys of Medication Decisions and Concordance
Twelve studies described how women or physicians make decisions to use medications to reduce risk for primary breast cancer (Appendix Table 2)65-76. In an interview-based, cross-sectional study after an educational session about indications and adverse effects of tamoxifen, women indicated that breast cancer (69%), pulmonary embolism (67%), endometrial cancer (63%), and deep venous thrombosis (58%) were “very important” in making their decisions about use69. Only 18% expressed interest in actually using tamoxifen. Another survey of eligible women indicated concerns for adverse effects, including endometrial cancer and thromboembolic events, lack of information, and reluctance to discontinue menopausal hormone therapy as reasons for not choosing tamoxifen70. Two other studies also described concerns about adverse effects67, 71.
In 2 similar studies, women reviewed online decision aids that provided their personal 5-year breast cancer risk and information about risk reduction with tamoxifen73 or tamoxifen and raloxifene74. Immediately after viewing the decision aid, 29% of women in the tamoxifen study were likely to seek more information, 30% were likely to discuss it with their physicians, 19% did not believe that tamoxifen would reduce their risk for breast cancer, and 6% were likely to take it in the next year73. Three months after viewing the decision aid, 1% of women had started taking tamoxifen, 6% had talked with their physicians, and 5% sought more information. Worry about side effects, belief that benefits were not worth the risks, and taking pills were cited as deterrents to use. Results were similar for the study considering both tamoxifen and raloxifene.
A study of women with elevated risk scores reported that 12% of women selected tamoxifen for breast cancer risk reduction, 77% declined, and 12% were undecided68. Major adverse effects (61%) and small benefit from tamoxifen (32%) were the most common reasons for declining. However, 90% of women stated that they would take a medication with the same benefit as tamoxifen if it had no side effects, and one half would take a medication with the same side effects as tamoxifen if it could eliminate the chance of getting breast cancer.
In another study, 75% of women indicated that they would take a medication for an assumed 60% lifetime risk for breast cancer, although they overestimated their personal lifetime risk for breast cancer by 2- to 3-fold75. Another survey indicated that 23% of responders interested in risk-reducing medications believed themselves to be at greater risk for breast cancer and were more worried about breast cancer than women who were not interested (P < 0.050)66. A study about interest in using tamoxifen reported that more than 40% of women would be willing to take tamoxifen if they were determined to be at “high risk”76. Asian women were more likely to take tamoxifen in this study (odds ratio, 3.0 [CI, 1.3 to 6.8]).
Of 350 physicians responding to a mailed survey, 27% had prescribed tamoxifen for breast cancer risk reduction within the previous 12 months65. Prescribers were more likely than nonprescribers to have a family member with breast cancer (20% vs. 9%) and believed that the benefits of tamoxifen outweigh the risks (63% vs. 39%), colleagues are prescribing it (33% vs. 17%), it is easy to determine who is eligible (28% vs. 11%), and many female patients ask for information about it (15% vs. 5%). Physician prescribers and nonprescribers did not differ in their beliefs about whether the evidence for use of tamoxifen is controversial, it is too time-consuming to discuss in practice, and the risks for thromboembolic events and endometrial cancer are too great.
Three studies reported the concordance of physicians' recommendations and their patients' medication decisions67, 71, 72. Women evaluated for benign breast findings in a breast clinic were provided with estimates of their breast cancer risks and the option of using tamoxifen for risk reduction71. They were then asked to discuss tamoxifen use with their family physicians. For 31% of the women, the family physician's advice was an important influence in their decision71. In another study, women whose physicians recommended enrollment in NSABP P-1 were 13 times more likely to enroll than women whose physicians recommended against enrollment (P < 0.001) 72. Women eligible for STAR who received recommendations for risk-reducing medications from their physicians were more likely to select treatment than those not getting recommendations67.
Adherence and Persistence in Clinical Trials
Seven primary prevention trials of tamoxifen and raloxifene7, 8, 10, 11, 24-43, 63, 77, 78 and 6 additional trials of raloxifene53, 57, 58, 79, 80 provided limited and heterogeneous data on adherence and persistence (Appendix Table 3). Adherence was reported in 2 placebo-controlled trials of tamoxifen28, 81 and 4 placebo-controlled trials of raloxifene7, 36, 60, 79. Of trials reporting adherence, at least 70% of participants used the planned treatment dose. In NSABP P-1, 41% of participants took 100% of study medication and 79% took at least 76% of study medication at 36 months81. Forgetting was the primary reason for nonadherence for 62% of women at 36 months. In the Royal Marsden Hospital trial, adherence was 8% lower with tamoxifen versus placebo (P = 0.002)28. In RUTH, adherence was similar between groups; approximately 70% took at least 70% of the study medication7. Adherence was not reported separately in MORE; 92% of the study population took at least 80% of the assigned study medication36.
Persistence was measured as duration of treatment in STAR48, 1 placebo-controlled trial of tamoxifen31, and 3 placebo-controlled trials of raloxifene7, 58, 79, and as completion of the planned course of treatment by 2 placebo-controlled trials of tamoxifen24, 31 and 6 placebo-controlled trials of raloxifene7, 57, 58, 60, 79, 80. Completion rates were similar between groups in STAR (71.5% for raloxifene vs. 68.3% for tamoxifen)48, the Italian Tamoxifen Prevention Study (59.8% for tamoxifen vs. 61.8% for placebo)31, IBIS-I (72% overall)24, and RUTH (80% for raloxifene vs. 79% for placebo)7. Additional trials of raloxifene reported 60% to 91% of participants completing the planned duration of treatment57, 58, 60, 79, 80.
Methods to Identify Women at Increased Risk for Breast Cancer
Nineteen studies evaluating 13 risk-stratification models met inclusion criteria (Appendix Table 4)82-102. Of these, 15 met criteria for good quality82-85, 87-90, 92-96, 99, 100. Four were rated as fair-quality because they inadequately described the population and follow-up97, provided estimates for 1-year risks only91, were not practical for primary care settings86, or were based on small or narrowly defined populations86, 98.
The Gail model, the first major breast cancer risk-stratification model to be used, was derived from multivariate logistic regression analysis of identified risk factors for breast cancer82. In the original version of the model, breast cancer incidence rates and baseline hazard rates were determined for invasive cancer, ductal carcinoma in situ, and lobular carcinoma in situ from a cohort of white women in the BCDDP (Breast Cancer Detection and Demonstration Project). The model was subsequently modified by using U.S. national data for invasive cancer from SEER (Surveillance, Epidemiology and End Results)83. From these data, the model was developed to allow the prediction of individualized absolute risk (probability) of developing invasive breast cancer in women having annual screening mammography over 5 years. This version is called the Gail-2 model or the Breast Cancer Risk Assessment Tool.
Subsequent risk-stratification models use a similar approach but vary in their use of reference standards and the variables they include (Appendix Table 5). The original Gail model included age, age at menarche, age of first birth, family history of breast cancer in first-degree relatives, number of previous breast biopsies, and history of atypical hyperplasia82. Subsequent models include 1 or more of these variables in addition to other factors. These include race87, 91, 92, 103, previous false-positive mammogram or benign breast disease91, 96, body mass index or height86, 87, 90, 91, 93, 97, 99, 100, estrogen and progestin use86, 87, 91, 93, history of breastfeeding87, menopause status or age91, 93, 97, smoking87, alcohol use86, 87, 93, physical activity86, 87, 100, education100, mammographic breast density90-92, and diet86.
Studies of Calibration
Calibration was calculated for 7 of the 13 models83, 85-88, 90-93, 97 (Appendix Table 5). For most models, the expected numbers of cases of breast cancer closely matched the observed numbers (expected–observed ratio, 0.90 to 1.10)83, 85-88, 90-93, 97. Calibration varied in specialized populations94, 95, for estrogen receptor–negative breast cancer83, and when outdated breast cancer incidence rates were used in the model104.
Studies of Discriminatory Accuracy
Most studies of risk models reported modest discriminatory accuracy estimates (c-statistic, 0.55 to 0.65) (Appendix Table 5)83-92, 94-96, 98-100. Only 1 study reported levels greater than 0.70 for both the Gail-2 (c-statistic, 0.74 [CI, 0.67 to 0.80]) and the Tyrer–Cuzick models (c-statistic, 0.76 [CI, 0.70 to 0.82])98. However, this study had limited applicability because it enrolled high-risk women and included only 54 cases of breast cancer. The Tyrer–Cuzick results were not replicated in a subsequent study (c-statistic, 0.54 [CI, 0.42 to 0.65])99. Overall, models that included breast density had the highest accuracy (c-statistic, 0.63 to 0.66)90-92.
Studies of Risk Thresholds
Some of the medication trials used individual risk scores for breast cancer as inclusion criteria8, 11, 48. Three studies evaluated this approach to risk stratification by determining calibration or discriminatory accuracy based on risk quintiles85, 87, 92, and 1 study determined these estimates based on a low (<1.67%) versus high (≥1.67%) 5-year risk threshold using the Gail model92. The 1.67% threshold was used as inclusion criteria for NSABP P-1 and STAR, and is included in the FDA indication for the use of tamoxifen and raloxifene for risk reduction.
The BCSC (Breast Cancer Surveillance Consortium)–Tice model demonstrated high calibration (expected–observed ratio, 0.99 to 1.03) but modest discriminatory accuracy across risk quintiles (c-statistic, 0.61 to 0.64)92. The Gail model showed high calibration in the higher risk quintiles despite a tendency to overpredict the number of invasive breast cancer cases, but inferior calibration in the lower quintiles with a tendency to underpredict85, 87.
The Table summarizes the evidence for all key questions in our review. Placebo-controlled primary prevention trials indicate that tamoxifen and raloxifene reduce the incidence of invasive breast cancer by 7 to 9 cases per 1000 women over a 5-year treatment period primarily by reducing estrogen receptor–positive breast cancer. New results from STAR show that tamoxifen has a greater effect than raloxifene by reducing invasive breast cancer by 5 fewer cases per 1000 women. Noninvasive breast cancer incidence and breast cancer–specific and all-cause mortality rates were not statistically significantly reduced by either medication, although trials were not powered for mortality. Both medications reduced fractures.
Although trials indicated that women at all levels of breast cancer risk had a reduction in breast cancer incidence with tamoxifen, those at highest risk (based on risk scores or preexisting atypical hyperplasia) derived the most benefit8. Benefits for higher-risk women were also demonstrated in a recent observational study of 2459 women with atypical breast lesions (atypical ductal and lobular hyperplasia; lobular carcinoma in situ) in a large health system105. Women who received tamoxifen, raloxifene, or exemestane had a 10-year breast cancer risk of 7.5% compared with women without treatment, who had a risk of 21.3% (P < 0.001). Risk was reduced for all types of atypia.
Beneficial effects of risk-reducing medications are countered by more thromboembolic events for both medications, with tamoxifen causing 4 more events per 1000 women than raloxifene in STAR. Tamoxifen also increases incidence of endometrial cancer and related gynecologic outcomes and cataracts compared with placebo and raloxifene. Many women have less serious adverse effects that impact quality of life and adherence, such as vasomotor, genital, and musculoskeletal symptoms. In trials, older women had more adverse effects for some outcomes, such as endometrial cancer and thromboembolic events, than women younger than 50 years.
Small descriptive studies indicate that women make decisions to use tamoxifen to reduce breast cancer risk based on their concern for adverse effects as well as their risk for breast cancer. Many women overestimate their risk for breast cancer but weigh their physicians' recommendations highly when deciding whether to take tamoxifen. Similar data for raloxifene are lacking, and no studies about how women choose among several risk-reducing medications have been published. Comparisons of adherence and persistence rates across medications in trials are limited because not all trials reported them, measures varied, and trials were designed for different treatment purposes. From the few trials reporting data about discontinuation, rates for tamoxifen or raloxifene were generally higher than placebo, but differences were low (≤2% for adverse events and ≤4% for nonprotocol specified events).
Research on risk assessment relevant to identifying candidates for risk-reducing medications includes 13 risk-stratification models for use in clinical settings. Models considered several risk factors for breast cancer and predicted 1-year to lifetime risk estimates. Most risk models demonstrated high calibration but low to modest discriminatory accuracy in predicting the probability of breast cancer in a person. Most models performed only slightly better than age alone as a risk predictor91, 94. Models that included breast density improved the predictive risk modestly91, although breast density may be imprecise and unavailable in many clinical practices. Research evaluating the Gail model score that has been used as a risk threshold in trials and for the FDA indication for use (5-year risk ≥1.67%) found that it has low discriminatory accuracy in predicting the probability of breast cancer in a person. Most women aged 60 years or older without other risk factors would meet this threshold by age alone.
This review is limited by potential publication bias and biases of our literature review process, such as using only English-language reports. Trials of medications varied in their inclusion criteria, surveillance, and ascertainment of outcomes. Active surveillance ended with completion of therapy in most trials, and important long-term outcomes may have been underreported, particularly mortality. Continued follow-up of women enrolled in existing trials would provide needed data on long-term outcomes. Risks for some adverse outcomes and population subgroups were underestimated because of lack of statistical power. Data are lacking for nonwhite, premenopausal, or elderly women who have comorbid conditions or are taking additional medications for other indications. Studies of patient choice and use of medications are small, are descriptive, and may not apply to other populations. Measures of adherence and persistence in clinical trials may not be similar for patients in clinical practices.
Evidence gaps include determination of optimal doses, duration, and timing of use; persistence of effects after treatment; and outcomes in population subgroups. The ATLAS (Adjuvant Tamoxifen: Longer Against Shorter) trial recently reported reduced recurrence of estrogen receptor–positive breast cancer and reduced breast cancer–specific and all-cause mortality rates in women with breast cancer after 10 versus 5 years of adjuvant therapy106. Whether a longer course provides a more favorable benefit–harm tradeoff for risk reduction in women without breast cancer has yet to be determined.
Trials of other medications have also demonstrated reduction in breast cancer risk, including tibolone5, lasofoxifene3, and exemestane4. Although they have not been FDA-approved for this purpose, they may expand clinical options. In the NCIC CTG MAP.3 (National Cancer Institute of Canada Clinical Trials Group Mammary Prevention.3) trial, exemestane reduced invasive breast cancer incidence by 65% after 3 years of therapy in postmenopausal women with increased risk for breast cancer, as determined by a Gail risk score greater than 1.66% or high-risk breast lesions4. Hot flashes and arthritis were more common among women taking exemestane, but other adverse effects were not different from placebo.
Despite previous recommendations to identify women at increased risk for breast cancer and offer risk-reducing medications2, use is low in the United States65. It is not clear how to identify candidates for therapy. Although the trials indicate broad benefit, subgroup analysis and decision models19 suggest that high-risk women, particularly those who had hysterectomies, may derive the most benefit with the least harms. Future research on clinical selection criteria reporting likelihood ratios of treatment thresholds would improve identification of candidates in practice settings and provide guidance for the appropriate use of risk-reducing medications.
Copyright and Source Information
Source: This article was first published in Annals of Internal Medicine (Ann Intern Med 2013;158:604-614).
Disclaimer: The findings and conclusions in this article are those of the authors, who are responsible for its content, and do not necessarily represent the views of AHRQ. No statement in this report should be construed as an official position of AHRQ or the U.S. Department of Health and Human Services.
Acknowledgments: Andrew Hamilton, MLS, MS, conducted literature searches, and Miranda Pappas, MA, Jennifer Mitchell, BA, and Amanda Brunton, BS, provided assistance (all are affiliated with the Oregon Health & Science University). Linda Humphrey MD, MPH (Portland Veterans Affairs Medical Center), and Peggy Nygren, MA, contributed to earlier versions of the evidence review.
Grant Support: By AHRQ (contract HHSA-290-2007-10057-1-EPC3).
Potential Conflicts of Interest: Dr. Nelson: Grant (money to institution): AHRQ. Support for travel to meetings (money to institution): AHRQ. Dr. Smith: Grant (money to institution): AHRQ. Ms. Griffin: None disclosed. Dr. Fu: Grant (money to institution): AHRQ. Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M11-1085.
Requests for Single Reprints: Heidi D. Nelson, MD, MPH, Pacific Northwest Evidence-based Practice Center, Oregon Health & Science University, Mailcode BICC, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239-3098; e-mail, firstname.lastname@example.org.
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- Schonfeld SJ, Pee D, Greenlee RT, Hartge P, Lacey JV Jr, Park Y, et al. Effect of changing breast cancer incidence rates on the calibration of the Gail model. J Clin Oncol. 2010;28:2411-7. [PMID: 20368565].
- Coopey SB, Mazzola E, Buckley JM, Sharko J, Belli AK, Kim EM, et al. The role of chemoprevention in modifying the risk of breast cancer in women with atypical breast lesions. Breast Cancer Res Treat. 2012;136:627-33. [PMID: 23117858].
- Davies C, Pan H, Godwin J, Gray R, Arriagada R, Raina V, et al; for the Adjuvant Tamoxifen: Longer Against Shorter (ATLAS) Collaborative Group. Long-term effects of continuing adjuvant tamoxifen to 10 years versus stopping at 5 years after diagnosis of oestrogen receptor-positive breast cancer: ATLAS, a randomised trial. Lancet. 2012. [PMID: 23219286].
Figure 1. Analytic Framework
1. In adult women without preexisting breast cancer, what is the comparative effectiveness of tamoxifen citrate and raloxifene when used to reduce risk for
primary breast cancer on improving short- and long-term health outcomes, including invasive breast cancer; noninvasive breast cancer, including DCIS;
breast cancer mortality; all-cause mortality; and osteoporotic fractures?
2. What are the harms of tamoxifen citrate and raloxifene when used to reduce risk for primary breast cancer?
3. How do outcomes vary by population subgroups?
4. How do benefits and harms affect decisions to use medications to reduce risk for primary breast cancer, concordance, adherence, and persistence?
5. What methods, such as clinical risk assessment models, have been used to identify women who could benefit from medications to reduce risk for primary
DCIS = ductal carcinoma in situ.
Figure 1 is an analytic framework for the key questions of this report that depicts the events that women without preexisting breast cancer could experience when undergoing selection as candidates for therapy with breast cancer risk-reducing medications. In general, the figure illustrates how using medications to reduce risk for primary breast cancer may result in reduced incidence of invasive breast cancer, noninvasive breast cancer, and fractures. The figure also looks at whether using medications to reduce risk for primary breast cancer improves mortality (both breast cancer-specific and all-cause). In addition, the figure depicts the possibility of adverse effects of risk-reducing medications.
Table. Summary of Evidence
|Key question 1: Benefits of tamoxifen and raloxifene when used to reduce risk for primary breast cancer|
|4 placebo-controlled trials of tamoxifen and 2 of raloxifene; 1 head-to-head trial||RCT||Trials are heterogeneous and lacked data on doses, duration, and timing of use||Consistent||High||Good|
|Findings: Tamoxifen and raloxifene reduced invasive breast cancer incidence by 30%–68% compared with placebo; tamoxifen had a greater effect than raloxifene in STAR. Noninvasive breast cancer incidence and mortality were not significantly reduced and did not differ between medications. Both reduced fracture incidence.|
|Key question 2: Harms of tamoxifen and raloxifene when used to reduce risk for primary breast cancer|
|4 placebo-controlled trials of tamoxifen; 14 trials and 1 study of raloxifene; 1 head-to-head trial||RCT and cohort||Trials are heterogeneous and lacked data on long-term effects||Consistent||High||Fair to good|
|Findings: Tamoxifen and raloxifene increased incidence of thromboembolic events compared with placebo; tamoxifen had a greater effect than raloxifene in STAR. Tamoxifen increased endometrial cancer incidence compared with placebo and raloxifene and increased incidence of cataracts compared with raloxifene. Both caused undesirable side effects for some women.|
|Key question 3: Variability of outcomes in population subgroups|
|4 placebo-controlled trials of tamoxifen and 2 of raloxifene; 1 head-to-head trial||RCT||Trials lacked data for women who are nonwhite, are premenopausal, or have comorbid conditions||Consistent||High||Fair|
|Findings: Risk reduction was greatest among women with >5% 5-y Gail model risk score or atypical hyperplasia for tamoxifen compared with placebo and raloxifene. Thromboembolic events and endometrial cancer were more common in women >50 y than younger women using tamoxifen.|
|Key question 4: Medication decisions and concordance, adherence, and persistence|
|Decisions: 11 studies; Adherence and persistence: 4 placebo trials of tamoxifen and 2 of raloxifene; 1 head-to-head trial||RCT and survey||Few decision studies included raloxifene; data on adherence and persistence were lacking||Could not determine||Unclear; data about decisions were descriptive and from small samples||Fair|
|Findings: Many women elect not to take tamoxifen because of harms. Trials provided limited data about adherence and persistence. Discontinuation rates for tamoxifen and raloxifene were generally slightly higher than placebo.|
|Key question 5: Methods to identify women at increased risk for breast cancer|
|19 studies of 13 models||Diagnostic accuracy||Studies varied by populations and risk parameters||Consistent||High||Good|
|Findings: Models have modest discriminatory accuracy in predicting the probability of breast cancer in a person (c-statistics between 0.55 and 0.65).|
RCT = randomized, controlled trial; STAR = Study of Tamoxifen and Raloxifene.
Appendix Figure. Summary of evidence search and selection
* Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews.
† Identified from reference lists, hand searching, and suggestions by experts.
‡ Studies that provided data and contributed to the body of evidence were considered “included.”
§ Some studies are included in more than 1 key question.
Appendix Table 1. Results of Primary Prevention Trials
|Outcome||Raloxifene vs. Tamoxifen||Tamoxifen vs. Placebo||Raloxifene vs. Placebo|
|RR (95% CI)||Events Reduced or Increased (95% CI), n*||RR (95% CI)||Trials, n†||Placebo Rate (±SE)‡||Events Reduced or Increased (95% CI), n*||RR (95% CI)||Trials, n†||Placebo Rate (±SE)‡||Events Reduced or Increased (95% CI), n*|
|Invasive breast cancer||1.24 (1.05–1.47)§||5 (1–9) fewer with tamoxifen||0.70 (0.59–0.82)||4||4.70 ± 1.02||7 (4–12) fewer with tamoxifen||0.44 (0.27–0.71)||2||3.19 ± 0.59||9 (4–14) fewer with raloxifene|
|ER+ breast cancer||0.93 (0.72–1.24)&||-||0.58 (0.42–0.79)||4||3.67 ± 0.78||8 (3–13) fewer with tamoxifen||0.33 (0.18–0.61)||2||2.45 ± 0.42||8 (4–12) fewer with raloxifene|
|ER− breast cancer||1.15 (0.75–1.77)&||-||1.19 (0.92–1.55)||4||-||-||1.25 (0.67–2.31)||2||-||-|
|Noninvasive breast cancer||1.22 (0.95–1.59)§||-||0.85 (0.54–1.35)¶||4||-||-||1.47 (0.75–2.91)||2||-||-|
|Breast cancer mortality||0.36 (0.08–1.21)§||-||1.07 (0.66–1.74)||4||-||-||NR**||-||-|
|All-cause mortality||0.84 (0.70–1.02)§||-||1.07 (0.90–1.27)||4||-||-||0.84 (0.64–1.10)††||2||-||-|
|Vertebral fracture||0.98 (0.65–1.46)&||-||0.75 (0.48–1.15)‡‡||-||-||0.61 (0.54–0.69)||2||3.45 ± 0.35§§||7 (5–9) fewer with raloxifene|
|Nonvertebral fracture||NR||-||0.66 (0.45–0.98)‡‡||1.55 ± 0.20||3 (0.2–5) fewer with tamoxifen||0.97 (0.87–1.09)||2||-||-|
|Thromboembolic events&&||0.75 (0.60–0.93)§||4 (1–7) more with tamoxifen||1.93 (1.41–2.64)||4||0.91 ± 0.19||4 (2–9) more with tamoxifen||1.60 (1.15–2.23)||2||2.34 ± 0.25||7 (2–15) more with raloxifene|
|DVT||0.72 (0.54–0.95)§||3 (1–5) more with tamoxifen||1.45 (0.89–2.37)||2||-||-||1.91 (0.87–4.23)||2||-||-|
|PE||0.80 (0.57–1.11)§||-||2.69 (1.12–6.47)||2||0.19 ± 0.07||2 (0.1–6) more with tamoxifen||2.19 (0.97–4.97)||2||-||-|
|CHD events||1.10 (0.85–1.43)&||-||1.00 (0.79–1.27)||4||-||-||0.95 (0.84–1.06)||2||-||-|
|Stroke||0.96 (0.64–1.43)&||-||1.36 (0.89–2.08)||4||-||-||0.96 (0.67–1.38)||2||-||-|
|Endometrial cancer||0.55 (0.36–0.83)§||5 (2–9) more with tamoxifen||2.13 (1.36–3.32)||3||0.75 ± 0.15||4 (1–10) more with tamoxifen||1.11 (0.65–1.89)††||3||-||-|
|Cataracts||0.80 (0.72–0.95)§||15 (8–22) more with tamoxifen||1.25 (0.93–1.67)¶¶||3||-||-||0.93 (0.84–1.04)||2||-||-|
CHD = coronary heart disease; DVT = deep venous thrombosis; ER- = estrogen receptor–negative; ER+ = estrogen receptor–positive; NR = not reported; NSABP = National Surgical Adjuvant Breast and Bowel Project; PE = pulmonary embolism; RR = risk ratio; RUTH = Raloxifene Use for the Heart; STAR = Study of Tamoxifen and Raloxifene.
* Numbers of events reduced for benefits or increased for harms compared with placebo or other comparator per 1000 women, assuming 5 y of use.
† If meta-analysis.
‡ Per 1000 women, estimated from a meta-analysis of rates from the placebo groups from the same trials included in the RRs.
§ Updated results from STAR22.
& Initial results from STAR48.
¶ Significantly reduced in NSABP P-1 (60 vs. 93 events; RR, 0.63 [CI, 0.45– 0.89])8.
** 2 breast cancer deaths in 7601 women for raloxifene vs. 0 in 7633 women for placebo (Grady et al, 201050).
†† Updated meta-analysis.
‡‡ NSABP P-18.
§§ Estimated from the placebo group of the RUTH trial7.
&& Includes DVT and PE.
¶¶ Significantly increased in NSABP P-1 (574 vs. 507 events; RR, 1.14 [CI, 1.01–1.29])11.
Appendix Table 2. Descriptive Studies of Decisions to Use Risk-Reducing Medications
|Author, Year (Reference)||Method||Population||Response Rate||Enrolled, n||Decision to Use Medication|
|Armstrong et al, 200665||Mailed survey to physicians about rates and reasons for prescribing tamoxifen||Primary care physicians, including family medicine, obstetrics and gynecology, and general internal medicine||47%||350||96 (27%) prescribed with tamoxifen within previous 12 mo||NA||NA|
|Bastian et al, 200166||Telephone survey about interest in using medications for breast cancer risk reduction||Women aged 40–55 y enrolled in a Blue Cross/Blue Shield Personal Care Plan; 8% had Gail score ≥1.66%||59% (1287/2165)*||1287||NR||NR||NR|
|Bober et al, 200467||In-person survey with telephone follow-up of decision making about using medications at 2 and 4 mo follow-up times||Women aged ≥35 y with a 5-y risk for breast cancer ≥1.7%; mean age, 52 y||82% (129/158)||129||37 (29%) prescribed with tamoxifen; 35 (27%) STAR enrollment†||31 (24%)†||26 (20%)†|
|Fagerlin et al, 201073||Online survey with decision aid about interest in using tamoxifen for breast cancer risk reduction||Women with increased risk for breast cancer; Gail 5-y risk, ≥1.66%; mean Gail score, 2.56% (range, 1.7%–17.3%); mean age, 59 y (range, 40–74 y)||8896 invited; 1218 accessed Web site; 749 eligible; 663 consented; 632 completed posttest||632||3 (0.9%)‡||NR||NR|
|Fagerlin et al, 201174||Online survey with decision aid about interest in using tamoxifen or raloxifene for breast cancer risk reduction||Women with increased risk for breast cancer, Gail 5-y risk, ≥1.66%; mean Gail score, 2.67% (range, 1.7%–19.1%); mean age, 62 y (range, 46–74 y)||14,048 invited; 2340 accessed Web site; 1299 eligible; 1197 consented; 1039 completed posttest; 712 completed 3-mo survey; 382 used decision aid||712||2/382 (0.5%) prescribed with raloxifene; 0 prescribed with tamoxifen§||209/382 (54.7%)||171/382 (44.8%)|
|Kaplan et al, 201276||In-person brief description of tamoxifen and interview about risk knowledge and interest in using tamoxifen for breast cancer risk reduction||Women from 4 racial or ethnic groups identified in primary care clinics; mean age, 59 y (range, 50–80 y)||88%||417||Likely to take tamoxifen if at high risk for breast cancer: white, 24.5%; black, 28.3%; Hispanic, 28.2%; Asian, 57.1%||NA||NA|
|McKay et al, 200568||Mailed survey with decision guide about using tamoxifen for breast cancer risk reduction||Women with increased risk for breast cancer; mean Gail score, 3.7% (range, 1.7%–9.4%); mean age, 52 y||77% (30/39)§||51||6 (11.8%)||38 (74.5%)||6 (11.8%)|
|Melnikow et al, 200569||Cross-sectional, mixed-methods interviews of attitudes and preferences for using tamoxifen for breast cancer risk reduction||Women at high risk for breast cancer; 32% aged 39–64 y, 44% aged 65–74 y, 25% aged ≥75 y||75% (255/341)||255||45 (17.6%)||206 (80.8%)||NR|
|Ozanne et al, 201075||Written questionnaire and in-person and phone interviews of interest in screening and prevention, including using medication for breast cancer risk reduction||Women at high risk for breast cancer at first visit to a cancer risk and prevention clinic; mean age, 40 y (range, 21–67 y)||83% (181/217) agreed to participate; 67% (146/217) completed all components||146||75% accepted medication for an assumed 65% lifetime risk||NA||NA|
|Port et al, 200170||Education session with surveys before and after of patient interest and acceptance of using tamoxifen for breast cancer risk reduction||Women with increased risk for breast cancer; mean age, 52.8 y (range, 39–74 y)||NR||43||2 (4.7%)||15 (34.9%)||26 (60.5%)|
|Taylor and Taguchi, 200571||Telephone survey of interest in using tamoxifen for breast cancer risk reduction||Women with a Gail score >1.6%; age, 35–80 y||99% (88/89)||89||1/48 (2%) women who discussed with physician||47/48 (98%) women who discussed with physician||NA|
|Yeomans Kinney et al, 199872||In-person survey of the effect of a physician’s recommendation to enroll in the NSABP P-1 trial||Women eligible for NSABP P-1 trial; mean age, 55 y; mean Gail score, 14.8%||75% (360/479) completed surveys; 23% (81/360) discussed tamoxifen with their physicians; 97% (175/181) reported their physicians’ recommendations||360||89/175 (51%) enrolled||86/175 (49%) did not enroll||NA|
NA = not applicable; NR = not reported; NSABP = National Surgical Adjuvant Breast and Bowel Project; STAR = Study of Tamoxifen and Raloxifene.
* After excluding ineligible women, completion rate was 76% and decline rate was 20%.
† 2-mo follow-up data.
‡ Medication decision at 3-mo follow-up. The denominator for the proportion was not provided in the publication.
§ 51 women were identified for participation and 39 agreed to participate. The 21 women who declined were included in the analysis as declining tamoxifen.
Appendix Table 3. Adherence and Persistence to Medications in Trials of Tamoxifen and Raloxifene
|Outcomes||Raloxifene vs. Tamoxifen||Tamoxifen vs. Placebo|
|Star48||NSABP P-111*||IBIS-I24||Royal Marsden28||Italian trial31|
|Adherence||NR||NR||41% full†; 79% adequate||NR||NR||8% less than placebo (P = 0.002)||NR||NR|
|Duration of treatment||46.8 mo||43.5 mo||NR||NR||NR||NR||NR||NR||47.4 mo||48.9 mo|
|Completion of treatment||71.5%||68.3%||NR||NR||63.9% (2287/3579) for 5 y||71.9% (2574/3579) for 5 y||NR||NR||59.8% (1615/2700) for 5 y||61.8% (674/2708) for 5 y|
|Discontinuation due to protocol specified event (major events)||NR||NR||NR||NR||NR||NR||NR||NR||7.6% (206/2700)||6.9% (188/2708)|
|Discontinuation due to non–protocol-specified event||NR||NR||23.7%||19.7%||NR||NR||NR||NR||26.7% (721/2700)||25.3% (686/2708)|
|Discontinuation due to adverse event||NR||NR||NR||NR||NR||NR||NR||NR‡||NR||NR|
|Outcomes||Raloxifene vs. Placebo|
|RUTH17||MORE36||Cohen et al53||Goldstein et al79||Lufkin et al57||McClung
|Adherence||70% vs. 71%
(P = 0.62)
|92%||NR||NR||86% to 90%§||NR||NR||NR||NR||NR||NR||91.6%||87.4%|
|Duration of treatment||Median exposure, 5.05 y||NR||NR||NR||NR||Mean duration, 2.3 y&||NR||NR||702 to 706 d**||NR||NR||NR||NR|
|Completion of treatment||80% vs. 79% (P = 0.02)¶||NR||NR||NR||60%§||91% (130/143)††||67%**||84.5% (109/129)‡‡||89.2%||87.4%|
|Discontinuation due to protocol specified event (major events)||NR||NR||NR||NR||NR||NR||NR||NR||0.7% (1/143)||NR||NR||NR||NR||NR||NR||NR|
|Discontinuation due to non–protocol-specified event||NR||NR||23.7%||19.7%||NR||NR||NR||NR||1.4% (2/143)||NR||NR||NR||NR||NR||NR||NR|
|Discontinuation due to adverse event||22% vs. 20% (P = 0.01||0.6% (33/5129) hot flashes||0.1% (2/2576) hot flashes (P < 0.001)||13.9%||17.6%§||5.6%
|13.5% (22/163)||14.5% (12/83)||8% (7/87)||10%
|Nonsignificant differences between groups|
IBIS = International Breast Cancer Intervention Study; MORE = Multiple Outcomes of Raloxifene Evaluation; NR = not reported; NSABP = National Surgical Adjuvant Breast and Bowel Project; RUTH = Raloxifene Use for the Heart; STAR = Study of Tamoxifen and Raloxifene.
* Adherence was reported in Land et al81 and discontinuation in Fisher et al11.
† Adherence at 36 mo was defined as full adherence (taking 100% of medication) and adequate adherence (at least 76% of medication).
‡ An earlier report of the Royal Marsden Hospital trial before enrollment was completed stated that the most frequent side effects leading to discontinuation were hot flashes and gynecologic problems (Powles et al27).
§ Includes a treatment group using conjugated equine estrogen.
& 3-y study period.
¶ Reported completion of “study” rather than “treatment.”
** Includes data relating to lasofoxifene.
†† 1-y study period.
‡‡ 2-y study period.
Appendix Table 4. Studies of Risk-Stratification Models
|Model||Population||Participants||Study Design||Comparison Group||Inclusion Criteria||Quality Rating|
et al, 200789
|Gail African American (invasive breast cancer)||BWHS; black women; aged ≥35 y from 1995–2003||725 case participants; 725 age-matched control participants||Validation; nested case–control; 8 y follow-up||SEER||Incident invasive breast cancer; must have complete data available||Good|
|Amir et al, 200398||Tyrer–Cuzick (10-y risk for invasive breast cancer)||Family history clinic at University Hospital of South Manchester, high-risk population; total population aged 21–73 y (median, 44 y); screened population age, 25–73 y (median, 46 y); from 1987–2001||64 case participants among 3150 women; subanalysis on screening population; 52 case participants among 1933-woman cohort||Women whose risk estimate could be derived by all the models were compared and only incident cases included||UK Northwest cancer registry||Complete risk data for all models being compared (Gail, Claus, Ford, Tyrer–Cuzick); excluded incomplete data||Fair*|
|Barlow et al, 200691||BCSC Barlow model (1-y risk for DCIS or invasive breast cancer)||BCSC; women without breast cancer; aged 35–84 y from 1996–2001||11,638 case participants from 2,392 998-woman cohort||Case participants within cohort of women being screened with mammography; 1 y follow-up||BCSC (compared with SEER)||DCIS or invasive breast cancer in women aged 35–84 y who had previous mammography within the last 5 y; no previous breast cancer, no breast augmentation; no previous mammography but detected breast cancer within 1 y of first mammography; if no data on menopause, excluded from subgroup analysis||Fair†|
|Boughey et al, 201099||Tyrer–Cuzick (10-y risk for invasive breast cancer)||Mayo benign breast disease cohort including women with benign breast biopsy results 1967–1991: mean age, 58.1 y; 1967–2009: median follow-up, 14.6 y (86.7% >5 y)||331 case participants with atypical hyperplasia in 9376-woman cohort with benign breast disease||Validation; nested case–control||NR||Women aged 18–85 y with diagnosis of atypical hyperplasia at time of biopsy||Good|
|Boyle et al, 200486||Italian-1 (all breast cancer)||Derivation: Italian multicenter case–control study of diet and breast cancer, 1991–1994; age of case participants, 23–74 y (mean, 55 y); control participants, 20–74 y (mean, 56 y).
Validation: Italian Tamoxifen Prevention Study, 1992–1997; age of case participants, 35–70 y (median age, 51 y)
|Derivation: 2569 case participants with 2588 control participants
Validation: 2700 participants taking tamoxifen, 2708 participants taking placebo
Validation: case participants in cohort
|Regional Cancer Registry Data||Women admitted with breast cancer diagnosed within 1 y of the study interview with no previous history of cancer; no admissions for gynecologic, neoplastic, hormonal diseases or those related to increased risk for breast cancer in control participants||Fair‡|
|Chen et al, 200690||Gail plus breast density (invasive breast cancer)||BCDDP; primarily white women aged >40 y; invasive or noninvasive cancer vs. control; data collected 1973–1979||2852 case participants (1235 with mammography density); 3146 age-matched control participants (1656 with mammography density)||Case–control; follow-up through 1998||SEER||Case participants with missing data excluded||Good|
|Chlebowski et al, 200787||Expanded and simplified models vs. Gail-2 (ER+ vs. ER− invasive breast cancer)||WHI; aged 50–79 y (mean, 63 y)||3236 case participants; 363 excluded due to missing data; 2873 for subgroup analysis; 2412 ER+ case participants; 461 ER− case participants; 144,680 control participants||Derivation and validation; case–control; 5 y follow-up||SEER||Unlikely to move or die within 3 y; no history of breast cancer or mastectomy||Good|
|Colditz and Rosner, 200093||Rosner–Colditz, Model 2 (invasive breast cancer)||NHS; aged 35–70 y; 1980–1994||1761 case participants among 58,520 women||Derivation; case participants within cohort of NHS; 14 y follow-up||Not compared||Incident invasive breast cancer. Exclusions include pregnancy/offspring history discrepancies; inaccurate age of menarche; unknown age of menopause or death; missing height, weight, or hormone use data; hysterectomy with 1 or no ovaries removed; or missing menopause data||Good|
|Colditz and Rosner, 200095||Rosner–Colditz, Model 2 (invasive breast cancer)||NHS; aged 35–79 y; 1980–2000||2096 case participants (1281 ER+/PR−, 417 ER−/PR−, 318 ER+/PR−, 80 ER−/PR+) among 66,145 women||Validation; case participants within cohort of NHS||NR||Invasive breast cancer with reported estrogen receptor status||Good|
|Costantino et al, 199983||Gail (invasive breast cancer)||BCPT; white women between 1992–1998||5969 women in placebo group of BCPT; 204 incident cases||Validation study of Gail-1 and -2 comparing BCDDP, CASH, NHS, BCPT cohorts; followup 1–70 mo (average 48.4)||BCDDP rates for invasive or noninvasive cancer (Gail-1); SEER data for invasive cancer (Gail-2)||10-y life expectancy, no history of breast cancer, negative mammogram within 180 d, negative clinical breast examination, no history of DCIS or LCIS||Good|
|Gail et al, 198982||Gail (invasive breast cancer and LCIS)||BCDDP; white women aged 35–79 y with invasive and noninvasive cancer between 1973–1979||2582 case participants, 3146 control participants||Derivation; case–control; abstracted risk factor information from 80% of eligible case participants and 83% of eligible control participants; follow-up through 1998||243,221 white women in BCDDP registry||10-y life expectancy, no history of breast cancer, negative mammography within 180 d, negative clinical breast examination, no history of DCIS||Good|
|Gail et al, 200788||Gail African American (invasive breast cancer)||CARE: black women; aged 35–64 y; 1994–1998 and 1993–1998||1607 case participants; 1647 control participants; women matched for 5-y age group, location, and race; 14,059 from WHI||Derivation: CARE
Validation: WHI case–control; WHI follow-up, 7.57 y
|SEER||SEER First primary incident invasive breast cancer in black women age 35–64 y; must have complete data available||Good|
|Petracci et al, 2011100||Italian-2 (invasive breast cancer)||Florence registry of the EPIC study
Derivation: age 23–74 y; 1991–1994
Validation: age 35–64 y; 1998–2004
|Derivation: 2569 case participants, 2588 control participants
Validation: 10,083 participants
|Florence EPIC cohort||Women aged 23–74 y with invasive breast cancer served as case participants; women aged 20–74 y without breast cancer and admitted for acute conditions to hospitals in the same catchment areas as the case patients served as control participants||Good|
|Rockhill et al, 200184||Gail (5-yr risk for invasive breast cancer)||NHS; white women aged 45–71 y in 1992; study duration, 1992–1997||1354 case participants in 82,109-woman cohort||Validation; prospective cohort; follow-up 60 mo||SEER||White women with complete risk factor data||Good|
|Rockhill et al, 200394||Rosner–Colditz, Model (invasive breast cancer)||NHS; aged 45–73 y; 1992–1997||757 case participants among 45,210 women||Validation; case participants within cohort of NHS||NR||Invasive breast cancer; no previous cancer, natural menopause or hysterectomy without oophorectomy, complete data||Good|
|Tamimi et al, 201096||Rosner–Colditz, adapted to include category of benign breast disease (invasive breast cancer)||NHS; aged 35–79 y; 1980–2000||240 case participants; 1036 control participants||Nested case–control within cohort of NHS; derivation||NR||Women with biopsy-proven benign breast disease; incident invasive breast cancer within this cohort with age and year of biopsy-matched control||Good|
|Tice et al, 200892||BCSC–Tice (invasive breast cancer)||BCSC; women without breast cancer aged 35–84 y; 71% white||1,095,484 women in cohort, 14,766 cases of invasive breast cancer; 629,229 for clinical risk factor analysis; 14,766 case participants||Case participants within cohort of women being screened with mammography; median follow-up, 5.3 y||SEER (BCSC vs. SEER, state tumor registries, and path databases)||Women aged ≥35 y with 1 previous mammography with BI-RADS measurement in BCSC; excluded women with diagnosis of breast cancer, women diagnosed within 6 mo of index mammography, and women with breast implants||Good|
|Tyrer et al, 200497||Tyrer–Cuzick (invasive breast cancer)||UK national statistics of breast cancer incidence rates in general population; BRCA risk tables from UK||NR||Derivation; data from other sources||UK rates of breast cancer and positive BRCA||NR||Fair&|
BCDDP = Breast Cancer Detection and Demonstration Project; BCPT = Breast Cancer Prevention Trial; BCSC = Breast Cancer Surveillance Consortium; BI-RADS = Breast Imaging-Reporting Data System; BWHS = Black Women's Health Study; CARE = Women's Contraceptive and Reproductive Experiences; CASH = Cancer and Steroid Hormone Study; DCIS = ductal carcinoma in situ; EPIC = European Prospective Investigation into Cancer and Nutrition; ER− = estrogen receptor–negative; ER+ = estrogen receptor–positive; LCIS = lobular carcinoma in situ; NHS = Nurses' Health Study; NR = not reported; PR– = progesterone receptor–negative; PR+ = progesterone receptor–positive; SEER = Surveillance, Epidemiology and End Results; UK = United Kingdom; WHI = Women's Health Initiative.
* Small sample size from a non–primary care setting.
† Short follow-up (1 y).
‡ Not practical for primary care settings, small sample size.
§ Italian–Gail Model: 1 calibration varies from Gail by 1 ordinal value for 1 variable; another varies by using categorical rather than ordinal variables.
& Developed using secondary data sources with inadequate description of the population and duration of follow-up.
Appendix Table 5. Risk-Stratification Models
|Age, y||Age at
|Age at Birth of
First Child, y
|Gail model variations|
|Gail-2 (5-y risk)||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; 1; ≥2||Biopsy: 0; 1; ≥2; AH: 0; ≥1||Not included||1.03 (0.88–1.21)83; 0.94 (0.89–0.99)84; 0.96 (0.84–1.17)85; 0.7987; 1.1286||0.55 (0.51–0.60)89; 0.6083; 0.58 (0.56–0.60)84; 0.5886; 0.59 (0.54–0.63)85; 0.6090; 0.61 (0.60–0.62)92|
|Gail-2 (10-y risk)||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; 1; ≥2||Biopsy: 0; 1; ≥2; AH: 0; ≥1||Not included||0.69 (0.54–0.90)94||0.74 (0.67–0.80)98|
|African American Gail (5-y risk)||<50; ≥50||≤13; >13||Not included||0; 1; ≥2||Biopsy: 0; 1; ≥2||African American race||1.08 (0.97–1.20)103||0.56 (0.54–0.58)103; 0.56 (0.51–0.60)89|
|Models with breast density|
|Chen (5-y risk)||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; 1; ≥2||Biopsy: 0; 1; ≥2||Breast density (%), BMI||NR||0.6490|
|45–84, by 5-y groups||Not included||Not included||0; 1; ≥2; unknown||Biopsy: yes; no; unknown||Breast density (BI-RADS)‡||1.0091||0.63 (0.60–0.66)91|
|BCSC† (postmenopausal; 1-y risk)||45–84, by 5-y groups||Not included||≤30; >30; none; unknown||0; 1; ≥2; unknown||Biopsy: 0; ≥1; unknown||Breast density (BI-RADS), previous false-positive mammogram, BMI, menopause type, HT, race or ethnicity||1.0191||0.62 (0.62–0.63)91|
|BCSC (5-y risk)||45–84, by 5-y groups||Not included||Not included||Yes; no||Biopsy: yes; no||Breast density (BI-RADS), race or ethnicity||1.01 (0.99–1.03)92||0.66 (0.65–0.66)92|
|Rosner–Colditz†||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||Yes; no||Not included||BMI, benign breast disease, menopause type, menopause age, HT use and duration, height, alcohol use, parity||1.00 (0.93–1.07)94||0.57 (0.55–0.59)94; 0.64 (0.63–0.66) (ER+/PR+)95; 0.61 (0.58–0.64) (ER+/PR−)95|
|Rosner–Colditz-2†||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||Yes; no||AH: 0; ≥1||Benign breast disease presence or type||1.01 (0.94–1.09)94||0.63 (0.61–0.65)94; 0.64 (type)94|
|Tyrer–Cuzick (10-y risk)||<50; ≥50||≤12; >12||≤30; >30;
|0–1; 2; ≥3||Biopsy: 0; 1; ≥2; LCIS: 0; ≥1||BMI, height, menopause age, family history of ovarian or other cancer, age of cancer onset, bilateral or male breast cancer||1.09 (0.85–1.41)98||0.76 (0.70–0.82)98; 0.54 (0.42–0.65)99|
|Italian-1§ (5-y risk)||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; 1; ≥2||Not included||Age of relative at diagnosis, diet score, alcohol use, BMI, HT, physical activity||1.0486||0.59 (vitamin)86; 0.60 (diet)86|
|Italian-2† (20-y risk)||<50; ≥50||≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; 1; ≥2||Biopsy: 0; 1; ≥2||Occupational and leisure physical activity, education, alcohol use, BMI||NR||0.62 (0.56–0.69) (age <50 y)100; 0.57 (0.52–0.61) (age ≥50 y)100|
|Chlebowski (5-y risk)||50–59;
|≤12; 12–13; ≥14||<20; 20–24; 25–29 or none; ≥30||0; ≥1||Biopsy: 0; 1; ≥2||BMI, menopause age, HT use and duration, race, alcohol use, parity, breastfeeding, smoking status, physical activity||NR||0.61 (0.59–0.63)87; 0.62 (0.60–0.64) (ER+)87; 0.53 (0.47–0.58) (ER−)87|
|Chlebowski, simplified (5-y risk)||<50; ≥50||Not included||Not included||0; ≥1||Biopsy: 0; 1; ≥2||Not included||NR||0.58 (0.56–0.60) (ER+)87|
AH = atypical hyperplasia; BCSC = Breast Cancer Surveillance Consortium; BI-RADS = Breast Imaging Reporting and Data System; BMI = body mass index; ER+ = estrogen receptor–negative; ER− = estrogen receptor–positive; HT = hormone therapy; LCIS = lobular carcinoma in situ; NR = not reported; PR− = progesterone receptor–negative; PR+ = progesterone receptor–positive.
* For invasive breast cancer, other outcomes are specifically indicated.
† Invasive and noninvasive breast cancer.
‡ BI-RADS categories include: 0 = unknown; 1 = entirely fat; 2 = scattered fibroglandular densities; 3 = heterogeneously dense; and 4 = extremely dense.
§ Includes an Italian population and used incidence rates from an Italian multicenter case–control study of diet and breast cancer and Italian cancer registries.
Internet Citation: Evidence Summary: Breast Cancer: Medications for Risk Reduction. U.S. Preventive Services Task Force. August 2016.