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Draft Recommendation Statement


Note: This draft Recommendation Statement is not the final recommendation of the U.S. Preventive Services Task Force. This draft is distributed solely for the purpose of pre-release review. It has not been disseminated otherwise by the USPSTF. It does not represent and should not be interpreted to represent a USPSTF determination or policy.

This draft Recommendation Statement is based on an evidence review that was published on July 30, 2013 (available at http://www.uspreventiveservicestaskforce.org/uspstf13/lungcan/lungcanart.htm).

The USPSTF makes recommendations about the effectiveness of specific preventive care services for patients without related signs or symptoms.

It bases its recommendations on the evidence of both the benefits and harms of the service, and an assessment of the balance. The USPSTF does not consider the costs of providing a service in this assessment.

The USPSTF recognizes that clinical decisions involve more considerations than evidence alone. Clinicians should understand the evidence but individualize decisionmaking to the specific patient or situation. Similarly, the USPSTF notes that policy and coverage decisions involve considerations in addition to the evidence of clinical benefits and harms.

This draft Recommendation Statement was available for comment from July 30 until August 26, 2013 at 5:00 PM ET. A fact sheet that explains the draft recommendations in plain language is available here.


Screening for Lung Cancer: U.S. Preventive Services Task Force Recommendation Statement
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Summary of Recommendation and Evidence

The U.S. Preventive Services Task Force (USPSTF) recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in persons at high risk for lung cancer based on age and smoking history.

This is a Grade B recommendation.

See the Clinical Considerations section for suggestions for implementation in practice.

Table 2 describes the USPSTF grades, and Table 3 describes the USPSTF classification of levels of certainty about net benefit.

Rationale

Importance

Lung cancer is the third most common cancer and the leading cause of cancer death in the United States (1). The most important risk factor for lung cancer is smoking, which results in approximately 85% of all lung cancer cases in the United States (2). Although the prevalence of smoking has declined, approximately 37% of U.S. adults are current or former smokers (2). The incidence of lung cancer increases with age, occurring most commonly in persons age 55 years or older. Increasing age and cumulative exposure to tobacco smoke are the two factors most strongly associated with the occurrence of lung cancer. Lung cancer has a poor prognosis, and nearly 90% of persons with lung cancer die of the disease. However, early-stage non-small cell lung cancer (NSCLC) has a better prognosis and can be treated with surgical resection.

Detection

The majority of lung cancer cases are NSCLC, and most screening programs focus on the detection and treatment of early-stage NSCLC. Although chest x-ray and sputum cytology have been used to screen for lung cancer, LDCT has greater sensitivity for detecting early-stage cancer (3).

Benefits of Detection and Early Treatment

The USPSTF found adequate evidence that annual screening for lung cancer with LDCT in current and former smokers ages 55 to 79 years who have significant cumulative tobacco smoke exposure can prevent a substantial number of lung cancer deaths. Direct evidence from a large, well-conducted randomized, controlled trial (RCT) provides moderate certainty of the benefit of lung cancer screening with LDCT in this population (4). The absolute magnitude of benefit depends on the population screened and the screening program used.

Harms of Detection and Early Intervention/Treatment

The harms associated with LDCT screening include false-negative and false-positive results, incidental findings, overdiagnosis, and radiation exposure. False-positive LDCT results occur frequently and often lead to further testing. False-positive results can usually be resolved by further imaging but some may require invasive procedures. The most common incidental findings on LDCT scans are emphysema and coronary artery calcifications. The USPSTF found insufficient evidence on the harms associated with incidental findings. Overdiagnosis of lung cancer occurs but the precise magnitude is uncertain. Radiation harms, including radiation-induced cancer resulting from cumulative scans over time, vary depending on the age at the start of screening and the number of scans received.

USPSTF Assessment

The USPSTF concludes with moderate certainty that annual screening for lung cancer with LDCT is of moderate net benefit in asymptomatic persons at high risk for lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting. See the Clinical Considerations for discussion of screening program guidelines. The moderate net benefit of screening depends on the accuracy of image interpretation being comparable to that found in the National Lung Screening Trial (NLST) and the resolution of most false-positive results without invasive procedures (4).

Clinical Considerations

Patient Population Under Consideration

The risk for lung cancer increases with age and cumulative exposure to tobacco smoke and decreases with time since quitting. Based on evidence from clinical trials and modeling studies, a reasonable balance of benefits and harms is obtained by screening healthy persons with a 30 pack-year or more history of smoking who are ages 55 to 79 years and have smoked within the past 15 years. Caution should be used in recommending screening to patients with significant comorbidity, particularly those who are toward the upper end of the screening age range. The NLST excluded persons who were unlikely to complete curative lung cancer surgery and those with any medical conditions that posed a significant risk for mortality during the 8-year trial period. The baseline characteristics of NLST showed a relatively healthy population, and less than 10% of enrolled participants were older than age 70 years (5). Persons with serious comorbid conditions may experience net harm, no net benefit, or at least substantially less net benefit.

Assessment of Risk

Age, total exposure to tobacco smoke, and years since quitting are important factors to consider when screening asymptomatic persons. The incidence of lung cancer is relatively low before age 50 years but increases with age, especially after age 60 years. Among current and former smokers, age-specific incidence rates increase with age and cumulative exposure to tobacco smoke. Smoking cessation substantially reduces a person's risk for developing and dying from lung cancer.

Screening Tests

LDCT has been shown to have high sensitivity and acceptable specificity for the detection of lung cancer. Chest x-ray and sputum cytology have not been found to have adequate sensitivity or specificity as screening tests. Therefore, LDCT is currently the only recommended screening test for lung cancer.

Screening Intervals and Starting and Stopping Ages

The NLST, the largest RCT to date with over 50,000 patients, enrolled participants ages 55 to 74 years at the time of randomization who had a tobacco use history of at least 30 pack-years and, if former smokers, had quit within the past 15 years (4). Smaller RCTs from Europe had different eligibility criteria and have not yet duplicated the findings of NLST; therefore, only moderate certainty exists about the magnitude of benefit from screening (3).

Estimates of the results of different screening intervals, ages at which to start and stop screening, and thresholds for smoking history come from modeling studies conducted for the USPSTF by the Cancer Intervention and Surveillance Modeling Network (CISNET). Annual screening with LDCT provides the greatest benefit in decreasing lung cancer mortality compared with biennial or triennial screening (6). Table 1 shows the results of annual screening strategies between the ages of 55 and 80 years that had a better balance of benefits and harms than other strategies in this age range. Focusing screening efforts on the highest-risk persons, those with a 40 or more pack-year smoking history, results in the lowest number of screening examinations per death averted and therefore the least harm to patients in terms of radiation exposure, risk for overdiagnosis, and consequences of false-positive results. Screening progressively larger proportions of the population by lowering the screening threshold increases the number of deaths averted but with a progressively higher number of scans per death averted, therefore increasing harm. Table 1 shows that increasing the proportion of the population screened from 13% to 36% increases the number of deaths averted by 75% but with the tradeoff of a 327% increase in the number of screening scans, greatly increasing the probability of an untoward event due to the evaluation of a false-positive test and the number of radiation-induced cancer deaths. The highlighted program—screening current or former smokers ages 55 to 79 years with a 30 pack-year or more smoking history and discontinuing screening (or not starting) after 15 years of smoking abstinence—which is the strategy that most closely resembles NLST patients, offers a reasonable balance of benefits and harms.

The CISNET study demonstrates similar life-years gained per death averted and proportion of cancer cases detected at an early stage across the screening strategies. The modeling studies estimate that 9.5% to 11.9% of screen-detected cancer cases are overdiagnosed; that is, are cancer that would not have been detected in the patient's lifetime without screening (6).

Table 1. Screening Scenarios From CISNET Models*

Screening Scenario** Benefits Harms*** CT screenings per lung cancer death averted
Minimum pack-years to screening Minimum age at which to begin screening Number of years since last cigarette to screening former smoker Percentage of population ever screened Proportion of lung cancer deaths averted Number of lung cancer deaths averted Total number of CT screenings Radiation-induced lung cancer deaths
40 60 25 13.0% 11.0% 410 171,924 17 419
40 55 25 13.9% 12.3% 458 221,606 21 483
30 60 25 18.8% 13.3% 495 253,095 21 511
30 55 15 19.3% 14.0% 521 286,813 24 550
20 60 25 24.8% 15.4% 573 327,024 25 583
30 55 25 20.4% 15.8% 588 342,880 25 570
20 55 25 27.4% 17.9% 664 455,381 31 685
10 55 25 36.0% 19.4% 721 561,744 35 777

* All scenarios model the results of following a cohort of 100,000 persons until death from all causes, with a varying number of smokers and former smokers screened based on smoking history, age, and years since stopping smoking.
** For all scenarios, screening is discontinued at age 80 years.
*** Number of CT screenings is a measure of harm because it relates to the number of patients who will experience radiation exposure, risk for overdiagnosis, and potential consequences from false-positive results.

Abbreviation: CISNET=Cancer Intervention and Surveillance Modeling Network; CT=computed tomography.

Treatment

Surgical resection is the current standard of care for localized NSCLC. NSCLC is treated with surgical resection when possible and also with radiation and/or chemotherapy. For patients with life-limiting comorbid conditions or poor functional status who may not be candidates for surgery, annual LDCT screening may not be useful. Clinicians should discuss with eligible patients whether or not screening for lung cancer is warranted if other comorbid conditions will preclude treatment. Shared decisionmaking regarding the balance of benefits and harms of screening should occur for all patients but especially for those who may not be candidates for treatment.

Other Approaches to Prevention

Smoking cessation is the most important intervention to prevent NSCLC. Advising smokers to stop smoking and preventing nonsmokers from tobacco smoke exposure are the most effective ways to decrease the morbidity and mortality associated with lung cancer. Current smokers should be informed of their continuing risk for lung cancer and offered cessation treatments. Screening with LDCT should be viewed as an adjunct to tobacco cessation interventions.

Useful Resources

There are many resources for clinicians to use to help patients stop smoking. The Centers for Disease Control and Prevention have developed a Web site with many resources aimed at helping persons stop smoking (http://www.cdc.gov/tobacco/campaign/tips/). The Web site leads patients to resources in several languages, including information on tobacco quitlines. Quitlines are telephone-based behavioral counseling and support to help tobacco users who want to quit. Counseling is provided by trained cessation specialists who follow standardized protocols that may include several sessions and are generally provided at no cost to users. The content has been adapted for specific populations and can be tailored for individual clients. Strong evidence exists that quitlines can expand the use of evidence-based tobacco cessation treatments in populations that may have limited access to treatment options.

Combination therapy with counseling and medications is more effective at increasing cessation rates than either component alone. The U.S. Food and Drug Administration has approved several forms of nicotine replacement therapy (gum, lozenge, transdermal patch, inhaler, and nasal spray), as well as bupropion and varenicline. More information on the treatment of tobacco dependence can be found in "Treating Tobacco Use and Dependence: Quick Reference Guide for Clinicians, 2008 Update" (available at http://www.ahrq.gov/professionals/clinicians-providers/guidelines-recommendations/tobacco/clinicians/reference/tobaqrg.pdf).

Other Considerations

Implementation

The evidence for the effectiveness of screening for lung cancer with LDCT comes from RCTs conducted in large academic medical centers with expertise in diagnosing and managing abnormal lung lesions using LDCT. Clinical settings that have high rates of diagnostic accuracy using LDCT, appropriate followup protocols for positive results, and clear criteria for performing invasive procedures are more likely to duplicate the results found in trials. Implementing lung cancer screening in community settings with similar expertise would increase the odds of achieving maximum benefits while minimizing harms.

Clinicians will encounter patients who do not meet the criteria of high risk for lung cancer as described previously. In these lower-risk patients, the balance of benefits and harms of screening may be unfavorable. Current evidence is lacking regarding the net benefit of expanding LDCT screening to include these lower-risk patients. It is important that persons at lower risk for lung cancer be aware of the potential harms of screening. Future improvements in risk assessment tools will help clinicians better individualize patients' risks (7).

Research Needs and Gaps

Smoking prevalence and lung cancer incidence are higher among socioeconomically disadvantaged populations, and more research is needed in these groups. In addition, if lung cancer screening with LDCT is implemented more widely in diverse community settings, it is important to evaluate whether the variability in followup protocols of positive scans may result in a different balance of benefits and harms compared with that observed in RCTs.

More research is also needed on the use of biomarkers to focus LDCT efforts among those at highest risk for lung cancer. The role of biomarkers to accurately discriminate between benign and malignant nodules and to identify more aggressive disease needs to be determined.

Discussion

Burden of Disease

Lung cancer is the third most common cancer in the United States. Age-adjusted incidence rates per 100,000 population are higher in men than women and vary according to the duration of and exposure to tobacco smoke. The most important risk factor for lung cancer is smoking, which results in approximately 85% of all lung cancer cases in the United States. Although the prevalence of smoking has declined, approximately 37% of U.S. adults are current or former smokers. Estimates from 2008 showed that 7 million persons in the United States ages 55 to 75 years had a 30 pack-year or more smoking history (2). The incidence of lung cancer increases with age, occurring most commonly in persons age 55 years or older. Lung cancer is the leading cause of cancer death in the United States, accounting for approximately 28% of all deaths from cancer. Lung cancer mortality is often related to the initial stage of diagnosis. The average 5-year survival for lung cancer is among the lowest (17%) of all types of cancer but is higher when it is diagnosed at an early stage (52%). However, only 15% of lung cancer cases are diagnosed early (2).

Scope of Review

To update the 2004 recommendation, the USPSTF commissioned a systematic evidence review to address the efficacy of LDCT, chest x-ray, and sputum cytology for lung cancer screening in asymptomatic persons at average or high risk (current or former smokers) (3). The review focused on new evidence from RCTs to determine the effectiveness of these screening tests in improving health outcomes. Information about the harms associated with the screening tests was obtained from RCTs and cohort studies. The benefits and harms associated with surgical resection of early-stage NSCLC were also examined.

In addition to the evidence review, the USPSTF also commissioned modeling studies from CISNET to provide information about the optimal age at which to begin and end screening, the optimal screening interval, and the relative benefits and harms of different screening strategies (6). The modeling studies were used to complement the evidence provided by the systematic review.

Accuracy of Screening Tests

The sensitivity of chest x-ray for detecting lung cancer varies depending on the size, location, image quality, and skill of the radiologist who interprets the test. LDCT has emerged as a test with higher sensitivity and specificity for lung cancer detection compared with chest x-ray. In 2004, the USPSTF found inadequate evidence to recommend for or against screening for lung cancer with LDCT, chest x-ray, sputum cytology, or a combination of these tests (I statement). Since then, a number of RCTs have been conducted and published, resulting in more data on the benefits and harms of screening. Recent data from NLST showed sensitivity of 93.8% and specificity of 73.4% for LDCT and sensitivity of 73.5% and specificity of 91.3% for chest x-ray (8). Sputum cytology is now rarely used for lung cancer screening, and no studies reported on the test characteristics of sputum cytology testing.

Effectiveness of Early Detection and Treatment

Four RCTs reported the effectiveness of LDCT for lung cancer screening. The largest trial, NLST, showed reduced lung cancer mortality of 16% (95% CI, 5.0 to 25.0) and reduced all-cause mortality of 6.7% (95% CI, 1.2 to 13.6) (9). This trial included over 50,000 asymptomatic men and women ages 55 to 74 years with at least a 30 pack-year smoking history. Participants were current or former smokers and were randomized to either LDCT or chest x-ray. They received annual testing at baseline and years 1 and 2 and were followed for a median of 6.5 years. After 6 to 7 years of followup, 2.06% of the chest x-ray group and 1.75% of the LDCT group had died from lung cancer, for an absolute difference of 0.31% and a number needed to screen of about 320 (4). The number needed to screen is based on three annual screenings; screening this same sample over a longer period of time should result in a much lower estimate.

In contrast to NLST, three small European trials showed either potential harm or no benefit of screening. Two small fair-quality trials, the Detection and Screening of Early Lung Cancer by Novel Imaging Technology and Molecular Essays Trial and the Danish Lung Cancer Screening Trial (DLCST), showed no benefit associated with LDCT compared with no LDCT (10–12). However, these were smaller trials (n=2,472 and n=4,104, respectively) that may have had limited power to detect a true benefit. Of note, the inclusion criteria in DLCST resulted in younger and healthier participants compared with the other trials. The relative risk for all-cause mortality in DLCST was 1.46 (95% CI, 0.99 to 2.15). This finding raises the possibility of potential harm of screening a young, healthy population. Followup in DLCST was 4.7 years (12). Combined data from DLCST and the Dutch-Belgian Randomized Lung Cancer Screening Trial will be reported in the near future (2).

When these three fair- or good-quality trials were combined in a meta-analysis, the relative risk for lung cancer mortality was 0.81 (95% CI, 0.72 to 0.91) (2). Another European trial, the Multicentric Italian Lung Detection study, was rated as poor-quality because of concerns about the adequacy of randomization; its results were not included in the final meta-analysis (13).

Two fair- to good-quality trials found no benefits associated with chest x-ray screening (2). The larger of these trials, the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, evaluated over 150,000 participants from the general population and found no benefits of chest x-ray screening in this group or in the subgroup with tobacco smoke exposure (14).

Potential Harms of Screening and Treatment

Harms associated with LDCT screening include false-negative and false-positive results, incidental findings, overdiagnosis, radiation exposure, and psychological distress. The sensitivity of LDCT ranged from 80% to 100%, suggesting a false-negative rate of 0% to 20%. The specificity of LDCT ranged from 28% to 100%. The positive predictive value for lung cancer of an abnormal test ranged from 2% to 42% (2). As mentioned previously, NLST is the largest trial of lung cancer screening to date, and recent results showed a sensitivity rate of 93.8% and specificity rate of 73.4% for LDCT. The positive predictive value for a positive finding of pulmonary nodules measuring 4 mm or larger in NLST was 3.8% (8). Over the three rounds of screening in NLST, 24.2% of screening tests were positive and 96.4% of these were false-positives. The vast majority of positive tests were followed by subsequent additional imaging. Approximately 2.5% of positive tests required additional invasive diagnostic procedures, such as bronchoscopy, needle biopsy, or thoracoscopy. Of the 17,053 positive tests evaluated, there were approximately 61 complications and six deaths after a diagnostic procedure. Recently published data from the first round of screening in NLST showed that the average number of followup scans per positive screening result was one scan per positive test. Approximately 1.9% of NLST participants had a biopsy (8).

The most common incidental findings on LDCT were emphysema and coronary artery calcifications. Other pulmonary findings included bronchiectasis, pulmonary fibrosis, carcinoid tumors, and hamartomas. The NLST reported clinically significant, nonlung cancer LDCT abnormalities of 7.5%. None of the studies reported data on the evaluations that may have occurred in response to the incidental findings. Therefore, the harms and benefits associated with incidental findings cannot be determined at this time (2).

Overdiagnosis was not formally reported in any study. The NLST found 119 more lung cancer cases among approximately 26,000 participants in the LDCT group compared with the chest x-ray group after 6.5 years of followup, suggesting some overdiagnosis. Recent data from the Italian Continuing Observation of Smoking Subjects cohort study of approximately 5,000 participants showed that of the 120 incident cancer cases, 25% were slow-growing or indolent (based on volume doubling time), thus possibly indicating a degree of overdiagnosis with LDCT (15).

Radiation exposure associated with LDCT ranged from 0.61 to 1.5 mSv per scan. To provide context, background radiation exposure in the United States averages 2.4 mSv per year, and radiation exposure from mammography is 0.7 mSv and 1.7 mSv for head CT. The risk for radiation-induced lung cancer depends on the age at which a person begins screening and the amount of cumulative radiation received. Based on modeling studies, starting annual LDCT screening before age 50 years may result in more radiation-related lung cancer deaths compared with starting annual screening after age 50 years (6).

Overall, LDCT screening did not seem to result in significant long-term psychological distress. No studies reported any long-term differences in anxiety or distress levels associated with LDCT in study participants.

No RCTs compared treating stage 1A or 1B lung cancer with surgical resection versus no treatment. Surgical resection is the standard of care in the United States for early-stage NSCLC. Studies of symptomatic and unselected patients report 5-year survival rates associated with surgical resection of 71% to 90% for stage 1A cancer and 42% to 75% for stage 1B cancer. No RCTs of LDCT screening evaluated the harms associated with screen-detected cancer. Studies that reported the harms of surgical resection were conducted in patients identified in clinical practice and with comorbid conditions (3).

Estimate of Magnitude of Net Benefit

Based on data from the systematic evidence review and modeling studies, the USPSTF determined with moderate certainty that annual LDCT screening provides substantial net benefit in high-risk persons ages 55 to 79 years. Evidence from NLST supports this recommendation, as participants in that trial were in this age range and had similar degree of lung cancer risk from cumulative tobacco exposure. Persons who do not meet the minimum eligibility criteria for NLST may have less net benefit and more harms from screening (ages 55 to 74 years at enrollment, ≥30 pack-year smoking history, and, if former smoker, ≤15 years since quitting). For these persons, the absolute benefit of screening is strongly associated with their age and smoking history.

Modeling studies conducted by CISNET researchers for the USPSTF showed that annual LDCT screening yielded the greatest net benefit (compared with biennial or triennial screening) (6). Benefits were measured as percent of early-stage detection of lung cancer, percent and absolute number of lung cancer deaths averted, and number of life-years gained. Harms were measured as number of total LDCT screenings per 100,000 population and per person, overdiagnosed lung cancer, and radiation-induced lung cancer deaths. The microsimulation models used standardized data on smoking history and nonlung cancer mortality to simulate the effects of various screening programs on the mortality of a U.S. cohort born in 1950. This cohort was chosen because these persons reach age 63 years (approximate midrange of participants' ages in NLST) in 2013.

Modeling evidence suggests that an annual screening program starting at age 55 years and ending at age 80 years (among current or former smokers with a 30 pack-year smoking history and <15 years since quitting) resulted in approximately 50% of lung cancer cases detected at an early stage (6). This screening protocol would result in a 14% reduction in lung cancer mortality, or an estimated 521 lung cancer deaths prevented per 100,000 persons in the population. The harms associated with this screening protocol are an estimated overdiagnosis of 4% and radiation-induced lung cancer deaths of less than 1%. As mentioned previously, a person's absolute net benefit from screening may depend not just on age but functional status and the presence of other comorbid conditions.

How Does Evidence Fit With Biological Understanding?

Lung cancer is a proliferation of malignant cells arising in the tissues or airways of the lungs. In addition to age and exposure to tobacco smoke, other risk factors for lung cancer include family history, chronic obstructive pulmonary disease, pulmonary fibrosis, and exposure to indoor cooking fumes, radon, asbestos, arsenic, chromium, and coal tar. NSCLC is a heterogeneous category that includes adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and undifferentiated carcinoma. Adenocarcinoma is the most common subtype, encompassing 36% of all lung cancer cases. Currently, 75% of patients with lung cancer present with symptoms of advanced local or metastatic disease that result in poor prognosis (2). At the earliest stage, median 5-year survival for NSCLC is 77%. Patients with localized disease (defined as cancer limited to the lung without metastasis to other organs or lymph nodes) have a median 5-year survival of 52% compared with 25% for regional spread and 4% for distant metastasis. Thus, earlier detection and treatment of lung cancer give patients a greater chance for cure.

Update of Previous USPSTF Recommendation

This recommendation updates the 2004 recommendation, in which the USPSTF concluded that the evidence was insufficient to recommend for or against screening for lung cancer in asymptomatic persons with LDCT, chest x-ray, sputum cytology, or a combination of these tests. In the current recommendation, the USPSTF recommends annual screening for lung cancer with LDCT in persons at high risk based on age and cumulative tobacco smoke exposure.

Recommendations of Others

In May 2012, the American College of Chest Physicians, the American Society of Clinical Oncology, and the American Thoracic Society (16) recommended screening for lung cancer using LDCT based primarily on results from NLST, with eligibility criteria that modeled closely on NLST (current or former smokers ages 55 to 74 years with a ≥30 pack-year history of cigarette smoking and ≤15 years since quitting). The recommendations also stipulated that screening should be offered only in clinical settings similar to those in the trial.

The American Association for Thoracic Surgery (17) recommends annual screening with LDCT in current and former smokers ages 55 to 79 years with a 30 pack-year history of smoking. It also recommends annual screening starting at age 50 to 79 years for patients with a 20 pack-year smoking history and additional comorbidity that produces a cumulative risk for developing cancer of at least 5% over the next 5 years. It also recommends annual screening in long-term cancer survivors ages 55 to 79 years.

In January 2013, the American Cancer Society (18) also began recommending screening for lung cancer with LDCT in high-risk patients in relatively good health who meet the NLST criteria (ages 55 to 74 years with a ≥30 pack-year smoking history, current smokers, or ≤15 years since quitting). It recommends against the use of chest x-ray and strongly suggests that all adults who receive screening enter an organized screening program that has experience in LDCT.

The National Comprehensive Cancer Network (19) also recommends LDCT screening in select patients at high risk for lung cancer. High-risk is defined as ages 55 to 74 years, 30 pack-year or more smoking history, and, if a former smoker, 15 years or less since quitting, or age 50 years or older, 20 pack-year or more smoking history, and one additional risk factor. Persons who are at moderate (age 50 years or older and ≥20 pack-year history of smoking tobacco or secondhand smoke exposure but no additional lung cancer risk factors) and low risk (younger than age 50 years and/or smoking history of <20 pack-years) are not recommended for lung cancer screening.

Table 2: What the Grades Mean and Suggestions for Practice

Grade Definition Suggestions for Practice
A The USPSTF recommends the service. There is high certainty that the net benefit is substantial. Offer or provide this service.
B The USPSTF recommends the service. There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial. Offer or provide this service.
C The USPSTF recommends selectively offering or providing this service to individual patients based on professional judgment and patient preferences. There is at least moderate certainty that the net benefit is small. Offer or provide this service for selected patients depending on individual circumstances.
D The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits. Discourage the use of this service.
I Statement The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined. Read the clinical considerations section of USPSTF Recommendation Statement. If the service is offered, patients should understand the uncertainty about the balance of benefits and harms.


Table 3: Levels of Certainty Regarding Net Benefit

Level of Certainty* Description
High The available evidence usually includes consistent results from well-designed, well-conducted studies in representative primary care populations. These studies assess the effects of the preventive service on health outcomes. This conclusion is therefore unlikely to be strongly affected by the results of future studies.
Moderate The available evidence is sufficient to determine the effects of the preventive service on health outcomes, but confidence in the estimate is constrained by factors such as:
  • The number, size, or quality of individual studies.
  • Inconsistency of findings across individual studies.
  • Limited generalizability of findings to routine primary care practice.
  • Lack of coherence in the chain of evidence.

As more information becomes available, the magnitude or direction of the observed effect could change, and this change may be large enough to alter the conclusion.

Low The available evidence is insufficient to assess effects on health outcomes. Evidence is insufficient because of:
  • The limited number or size of studies.
  • Important flaws in study design or methods.
  • Inconsistency of findings across individual studies.
  • Gaps in the chain of evidence.
  • Findings not generalizable to routine primary care practice.
  • A lack of information on important health outcomes.

More information may allow an estimation of effects on health outcomes.

*The U.S. Preventive Services Task Force defines certainty as "likelihood that the USPSTF assessment of the net benefit of a preventive service is correct." The net benefit is defined as benefit minus harm of the preventive service as implemented in a general, primary care population. The USPSTF assigns a certainty level based on the nature of the overall evidence available to assess the net benefit of a preventive service.

References

1. American Cancer Society. Cancer Facts & Figures 2013. Atlanta: American Cancer Society; 2013. Accessed at http://www.cancer.org/research/cancerfactsfigures/cancerfactsfigures/cancer-facts-figures-2013 on 15 July 2013.
2. Humphrey L, Deffebach M, Pappas M, Baumann C, Artis K, Priest Mitchell J, et al. Screening for Lung Cancer: Systematic Review to Update the U.S. Preventive Services Task Force Recommendation Statement. Evidence Synthesis No. 105. AHRQ Publication No. 13-05196-EF-1. Rockville, MD: Agency for Healthcare Research and Quality; 2013.
3. Humphrey LL, Deffebach M, Pappas M, Baumann C, Artis K, Priest Mitchell J, et al. Screening for lung cancer with low-dose computed tomography: a systematic review to update the U.S. Preventive Services Task Force recommendation. Ann Intern Med. 2013. [Epub ahead of print 30 July 2013].
4. National Lung Screening Trial Research Team; Aberle DR, Adams AM, Berg CD, Black WC, Clapp JD, et al. Reduced lung-cancer mortality with low-dose computed tomographic screening. New Engl J Med. 2011;365(5):395-409.
5. National Lung Screening Trial Research Team; Aberle DR, Adams AM, Berg CD, Clapp JD, Clingan KL, et al. Baseline characteristics of participants in the randomized National Lung Screening Trial. J Natl Cancer Inst. 2010;102(23):1771-9.
6. de Koning HJ, Plevritis S, Hazelton WD, ten Haaf K, Munshi V, Jeon J, et al. Benefits and Harms of Computed Tomography Lung Cancer Screening Programs for High-Risk Populations. AHRQ Publication No. 13-05196-EF-2. Rockville, MD: Agency for Healthcare Research and Quality; 2013.
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8. National Lung Screening Trial Research Team; Church TR, Black WC, Aberle DR, Berg CD, Clingan KL, et al. Results of initial low-dose computed tomographic screening for lung cancer. New Engl J Med. 2013;368(21):1980-91.
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19. National Comprehensive Cancer Network. National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology: Lung Cancer Screening. Fort Washington, PA: National Comprehensive Cancer Network; 2012.

AHRQ Publication No. 13-05196-EF-3
Current as of August 2013


Internet Citation:

U.S. Preventive Services Task Force. Screening for Lung Cancer: Draft Recommendation Statement. AHRQ Publication No. 13-05196-EF-3. http://www.uspreventiveservicestaskforce.org/uspstf13/lungcan/lungcandraftrec.htm



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