Draft Recommendation Statement
Lung Cancer: Screening
July 07, 2020
Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.
- Update in Progress for Lung Cancer: Screening
|Adults ages 50 to 80 years who have a 20 pack-year smoking history, currently smoke, or have quit within the past 15 years||The USPSTF recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults ages 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.||B|
Recommendations made by the USPSTF are independent of the U.S. government. They should not be construed as an official position of the Agency for Healthcare Research and Quality or the U.S. Department of Health and Human Services.
Lung cancer is the second most common cancer and the leading cause of cancer death in the United States. In 2020, an estimated 228,820 persons will be diagnosed with lung cancer, and 135,720 persons will die from the disease.1
The most important risk factor for lung cancer is smoking.2, 3 Smoking is estimated to account for about 90% of all lung cancer cases,2 with a relative risk of lung cancer approximately 20-fold higher in smokers compared with nonsmokers.3 Increasing age is also a risk factor for lung cancer. The median age of diagnosis of lung cancer is 70 years.4, 5
Lung cancer has a generally poor prognosis, with an overall 5-year survival rate of 20.5%.1 However, early-stage lung cancer has a better prognosis and is more amenable to treatment.
The USPSTF concludes with moderate certainty that annual screening for lung cancer with LDCT is of moderate net benefit in persons at high risk for lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting smoking. The moderate net benefit of screening depends on limiting screening to persons at high risk, the accuracy of image interpretation being similar to or better than that found in clinical trials, and the resolution of most false-positive results without invasive procedures.
Patient Population Under Consideration
This recommendation applies to adults ages 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years.
Assessment of Risk
Smoking and older age are the two most important risk factors for lung cancer.3-5 The relative risk of lung cancer in smokers is approximately 20-fold that of nonsmokers, increases with cumulative quantity and duration of smoking, increases with age, and for former smokers, decreases with increasing time since quitting.3 The USPSTF considers adults ages 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years to be at high risk, and recommends screening for lung cancer with annual LDCT in this population.
LDCT has high sensitivity and reasonable specificity for the detection of lung cancer, with demonstrated benefit in screening persons at high risk.6-8 Other potential screening modalities include sputum cytology, chest x-ray, and biomarkers. These modalities have not been found to be beneficial.9, 10
The two lung cancer screening trials that showed a benefit of lung cancer screening used different screening intervals. The National Lung Screening Trial (NLST) screened annually for 3 years.6 The Nederlands-Leuvens Longkanker Screenings Onderzoek (NELSON) trial screened at intervals of 1 year, then 2 years, then 2.5 years.8 Modeling studies from the Cancer Intervention and Surveillance Modeling Network (CISNET) suggest that annual screening for lung cancer leads to greater benefit compared with biennial screening.11 Based on the available evidence, the USPSTF recommends annual screening.
Treatment and Interventions
Lung cancer can be treated with surgery, chemotherapy, radiation therapy, newer targeted immunotherapies, or combinations of these treatments.12 Surgical resection is the treatment of choice for eligible patients with Stage I or II non-small cell lung cancer (NSCLC).13
Implementation of Lung Cancer Screening
Screening Eligibility, Screening Intervals, and Starting and Stopping Ages
As noted above, the USPSTF recommends annual screening for lung cancer with LDCT in adults ages 50 to 80 years who have at least a 20 pack-year smoking history. Screening should be discontinued once a person has not smoked for 15 years.
The NLST6 and the NELSON8 trial enrolled generally healthy persons, and those study findings may not accurately reflect the balance of benefits and harms in persons with comorbid conditions. The USPSTF recommends discontinuing screening if a person develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
Smoking Cessation Counseling
All persons enrolled in a screening program who are current smokers should receive smoking cessation interventions. To be consistent with the USPSTF recommendation on counseling and interventions to prevent tobacco use and tobacco-caused disease,14 persons who are referred to a lung cancer screening program through primary care should receive these interventions concurrent with referral. Because many persons may enter screening through pathways besides referral from primary care, the USPSTF encourages incorporating such interventions into the screening program.
Shared Decision Making
Shared decision making is important when clinicians and patients discuss screening for lung cancer. The benefit of screening varies with risk because persons at higher risk are more likely to benefit. Screening does not prevent most lung cancer deaths, and smoking cessation remains essential. Lung cancer screening has the potential to cause harm, including false-positive results and incidental findings that can lead to subsequent testing and treatment, including the anxiety of living with a lung lesion that may be cancer. Overdiagnosis of lung cancer and the risks of radiation exposure are harms, although their exact magnitude is uncertain. The decision to undertake screening should involve a thorough discussion of the potential benefits, limitations, and harms of screening.
Standardization of LDCT Screening and Followup of Abnormal Findings
The randomized, controlled trials (RCTs) that provide evidence for the benefit of screening for lung cancer with LDCT were all conducted in academic centers with expertise in the performance and interpretation of LDCT, the management of lung lesions seen on LDCT, and the treatment of lung cancer. Clinical settings that have similar experience and expertise are more likely to duplicate the beneficial results found in trials.
In an effort to minimize the uncertainty and variation about the evaluation and management of lung nodules, and standardize the reporting of LDCT screening results, the American College of Radiology developed the Lung Imaging Reporting and Data System (Lung-RADS™) classification system, and endorses its use in lung cancer screening.15 Lung-RADS provides guidance to clinicians on which findings are suspicious for cancer and the suggested management of lung nodules detected on LDCT. Data suggest that the use of Lung-RADS may decrease the rate of false-positive results in lung cancer screening.16
Additional Tools and Resources
The CDC has several websites with many resources to help patients stop smoking:
- “How to Quit” resources (https://www.cdc.gov/tobacco/quit_smoking/how_to_quit/index.htm)
- “Smoking Cessation: Fast Facts” (https://www.cdc.gov/tobacco/data_statistics/fact_sheets/cessation/quitting/index.htm)
- “Tips From Former Smokers” (https://www.cdc.gov/tobacco/campaign/tips/)
Information on the treatment of tobacco dependence can be found in the U.S. Public Health Service reference guide “Treating Tobacco Use and Dependence” (https://www.ahrq.gov/professionals/clinicians-providers/guidelines-recommendations/tobacco/clinicians/update/index.html).
The National Cancer Institute has developed patient and clinician guides on screening for lung cancer:
- “Lung Cancer Screening (PDQ®)–Patient Version” (https://www.cancer.gov/types/lung/patient/lung-screening-pdq)
- “Lung Cancer Screening (PDQ®)–Health Professional Version” (https://www.cancer.gov/types/lung/hp/lung-screening-pdq)
Other Related USPSF Recommendations
Smoking cessation is the most important intervention to prevent lung cancer. The USPSTF has made recommendations on the use of pharmacotherapy and counseling for tobacco cessation.14
When final, this recommendation will replace the 2014 USPSTF recommendation on screening for lung cancer. In 2014, the USPSTF recommended annual screening for lung cancer with LDCT in adults ages 55 to 80 years who have a 30 pack-year smoking history and currently smoke or have quit within the past 15 years (abbreviated as A-55-80-30-15).17 For the current draft recommendation, the USPSTF has changed the age range and pack-year eligibility criteria, and recommends annual screening for lung cancer with LDCT in adults ages 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15).
As in the 2014 recommendation, the USPSTF recommends that screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
Scope of Review
To update its 2014 recommendation, the USPSTF commissioned a systematic review18 on the accuracy of screening for lung cancer with LDCT and the benefits and harms of screening for lung cancer. The review also assessed whether the benefits of screening vary by subgroup (e.g., by race or sex) or by the number or frequency of LDCT scans, and whether the harms associated with screening and the evaluation of lung nodules differ with the use of Lung-RADS, International Early Lung Cancer Action Program (I-ELCAP), or similar approaches (e.g., to reduce false-positive results). In addition, the review assessed whether the use of risk prediction models for identifying adults at higher risk of lung cancer mortality improves the balance of benefits and harms of screening compared with the use of trial eligibility criteria or the prior USPSTF recommendation criteria.
In addition to the systematic evidence review, the USPSTF commissioned collaborative modeling studies from CISNET11 to provide information about the optimum age at which to begin and end screening, the optimum screening interval, and the relative benefits and harms of different screening strategies, including risk factor–based strategies based on age, pack-year smoking history, and years since quitting smoking for former smokers, compared with modified versions of multivariate risk prediction models. The modeling studies complement the evidence that the systematic review provides.
Accuracy of Screening Tests
The USPSTF reviewed several RCTs and cohort studies that reported on the sensitivity, specificity, or predictive value of LDCT.18 Not all of the reviewed studies reported all test accuracy data. In the studies that reported it, sensitivity ranged from 59% to 100%, specificity ranged from 26.4% to 99.7%, positive predictive value ranged from 3.3% to 43.5%, and negative predictive value ranged from 97.7% to 100%.
In the NLST and NELSON trial, the reported sensitivities were 93.1% and 59%, respectively, and reported specificities were 76.5% and 95.8%, respectively.8, 19 Although the negative predictive values were similar for the NLST and NELSON trial (99.9% and 97.7%, respectively), the positive predictive values were very different (3.3% and 43.5%, respectively). This difference is potentially accounted for by the differences in the trials’ definitions of a positive finding and screening protocols—the NELSON trial used a volumetric approach and added an indeterminate nodule result category (i.e., an indeterminate finding was not considered a positive result even if it led to additional testing) the NLST used an approach of maximum diameter without an indeterminate category (i.e., any nodule meeting the diameter criteria was considered a positive result).
Two retrospective studies compared use of Lung-RADS and I-ELCAP protocols for nodule classification with the NLST protocol.16, 20 The first study demonstrated that using Lung-RADS in the NLST would have increased specificity while decreasing sensitivity (16). The second study found that use of I-ELCAP criteria (increase in nodule size threshold to 5 mm) would increase positive predictive value; however, this study did not calculate other test characteristics (i.e., sensitivity, specificity, or negative predictive value).20
Benefits of Early Detection and Treatment
The NLST, the largest RCT to date (n=53,454), 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 were current smokers or had quit within the past 15 years. The mean pack-year smoking history in NLST participants was 56 pack-years.6 The NELSON trial (n=15,792) enrolled participants ages 50 to 74 years who had a tobacco use history of at least 15 cigarettes a day (three-fourths a pack per day) for more than 25 years or 10 cigarettes a day (half a pack per day) for more than 30 years and were current smokers or had quit within the past 10 years. The median pack-year smoking history in NELSON trial participants was 38 pack-years.8
The NLST reported a relative risk reduction in lung cancer mortality of 16% (95% confidence interval [CI], 5 to 25).7 At 10 years of followup, the NELSON trial reported 181 lung cancer deaths among participants in the screening group and 242 in the control group (incidence rate ratio [IRR], 0.75 [95% CI, 0.61 to 0.90]).8, 18 The NLST also found a reduction in all-cause mortality with LDCT screening compared with chest x-ray (IRR, 0.93 [95% CI, 0.88 to 0.99]). Results of the other trials were imprecise and did not show statistically significant differences between screening with LDCT and no screening.18
Evidence on screening interval comes from the NLST and the NELSON trial and CISNET modeling studies. The NLST screened annually for 3 years.6 The NELSON trial screened at intervals of 1 year, then 2 years, then 2.5 years.8 The CISNET modeling studies suggest that annual screening with LDCT provides greater benefit in decreasing lung cancer mortality and in life-years gained compared with biennial screening.11
Several lines of evidence suggest that screening for lung cancer in persons with lighter smoking histories (i.e., fewer than the 30 pack-year eligibility criterion of the 2014 USPSTF recommendation) and at an earlier age can increase the benefits of screening. As noted, the NELSON trial enrolled persons ages 50 to 74 years with a lighter smoking history (half a pack per day for more than 30 years or three-fourths a pack per day for more than 25 years).8 This trial provides empiric evidence for the benefit of screening for lung cancer with LDCT in younger persons with lighter pack-year smoking histories.
The CISNET modeling studies also provide data that can help inform the ages at which to start and stop screening and pack-year eligibility criterion for lung cancer screening. The USPSTF focused on screening programs in the 1960 birth cohort (persons who are more representative of current smoking patterns compared with older cohorts) that yielded mortality reductions at least as great as the 2014 USPSTF screening program (A-55-80-30-15). For such screening programs that fall on or near the efficient frontier (i.e., they maximize benefits for any given level of LDCT screening) for both lung cancer deaths averted and life-years gained in at least three out of the four models (i.e., “consensus-efficient” programs), the majority (52%) have a minimum pack-year eligibility criterion of 20 pack-years. Almost all have a starting age of 50 or 55 years, and all have a stopping age of 80 years.11
The CISNET modeling studies suggest that the 2014 USPSTF screening program (A-55-80-30-15) would reduce lung cancer mortality by 9.8%, and avert 381 lung cancer deaths and lead to 4,882 life-years gained per 100,000 persons in the population ages 45 to 90 years over a lifetime of screening. A range of consensus-efficient screening programs using a 20 pack-year eligibility criterion would reduce lung cancer mortality by 12.1% to 14.4% and avert 469 to 558 lung cancer deaths and lead to 6,018 to 7,596 life-years gained per 100,000 persons in the population ages 45 to 90 years.11 A program that annually screens persons ages 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would reduce lung cancer mortality by 13.0%, avert 503 lung cancer deaths, and lead to 6,918 life-years gained. Thus, this screening program leads to important gains in lung cancer deaths averted and life-years gained, and is supported by trial data and the CISNET modeling studies.
Screening for lung cancer in persons with lighter smoking histories (i.e., 20 pack-years) and at an earlier age may also help partially ameliorate racial disparities in screening eligibility. African Americans have a higher risk of lung cancer compared with whites, and this risk difference is more apparent at lower levels of smoking intensity.21 One recent analysis of Southern Community Cohort Study participants found that 17% of African American smokers were eligible for lung cancer screening based on the 2014 USPSTF eligibility criteria compared with 31% of white smokers. In the same study, among persons diagnosed with lung cancer, a significantly lower percentage of African American smokers (32%) was eligible for screening compared with white smokers (56%).22 A strategy of screening persons ages 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would lead to a relative increase in the percentage of persons eligible for screening by 86% overall, 77% in non-Hispanic whites, and 105% in non-Hispanic blacks compared with 2014 USPSTF criteria (A-55-80-30-15)11 Additionally, female smokers accumulate fewer pack-years than male smokers,23 and a strategy of screening persons ages 50 to 80 years who have at least a 20 pack-year smoking history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would lead to a relative increase in the percentage of persons eligible for screening by 81% in men and by 96% in women.11
It has been suggested that the use of risk prediction models to determine eligibility for lung cancer screening could increase the number of screen-preventable lung cancer deaths and reduce the number of participants needed to screen to prevent one lung cancer death. The CISNET modeling studies commissioned by the USPSTF thus compared the benefits and harms of screening programs based on risk prediction models compared with risk factor–based screening. The risk prediction models used were modified versions of the PLCOm2012 model,24 the Lung Cancer Death Risk Assessment Tool (LCDRAT) model,25 and the Bach model,26 limited to age, sex (for those models that include it as a variable, such as the LCDRAT and Bach models), smoking intensity, and smoking duration (and setting other potential variables such as race, education, body mass index, personal history of cancer, or family history of lung cancer to their reference value). In general, use of risk prediction models shifts screening to persons of older age (because age is an important risk factor for lung cancer). Although it increases the number of lung cancer deaths averted, as screening occurs when risk is highest, the effect on life-years gained is mixed because screening occurs when there are fewer years to be gained. Many risk prediction model–based screening programs slightly increase life-years gained, while some do not, or lead to a slight decrease in life-years gained. Use of risk prediction models also leads to an increase in the rate of overdiagnosed lung cancers, as overdiagnosed cancers are more common in older individuals.11
It is possible that the use of a more complex, computer-based risk prediction model to determine eligibility might impose a barrier to wider implementation and uptake of lung cancer screening. Additionally, it is possible that by shifting screening to persons of older age, use of risk prediction models to determine eligibility might lead to screening patients with comorbidities and shorter life expectancy, thus adversely affecting the balance of the benefits and harms of screening. Because the potential advantages of risk prediction model–based screening eligibility are all exclusively derived from simulation studies, they are subject to potential assumptions and extrapolations. Thus, the potential benefits of lung cancer screening based on risk prediction models are subject to uncertainty regarding their implementation, and there is insufficient evidence to assess whether or not risk prediction model–based screening would improve outcomes relative to using the risk factors of age and smoking history.
Harms of Screening and Treatment
Harms of screening can include false-positive results leading to unnecessary tests and invasive procedures, overdiagnosis, radiation-induced cancer, incidental findings, and increases in distress or anxiety.
The NLST reported false-positive rates for baseline, year 1, and year 2 of 26.3%, 27.2%, and 15.9%, respectively.6 The NELSON trial reported false-positive rates of 19.8% at baseline, 7.1% at year 1, 9.0% for males at year 3, and 3.9% for males at year 5.5 of screening.8, 27 An implementation study through the Veterans Administration revealed a false-positive rate of 28.9% of veterans eligible for screening (58% of those who were actually screened) at baseline.28 One retrospective study assessed how use of Lung-RADS would have changed the false-positive result rate in the NLST, and found a false-positive rate for Lung-RADS of 12.8% (95% CI, 12.4% to 13.2%) vs. 26.6% (95% CI, 26.1% to 27.1%) for the NLST approach.16
The most significant harms of false-positive results occur in the workup of these lesions, which can include further imaging, biopsy, or surgical procedures. Fourteen studies reported on the evaluation of false-positive results. Among all patients screened, the percentage who had a needle biopsy for a false-positive result ranged from 0.09% to 0.56%. Complication rates from needle biopsy for false-positive results ranged from 0.03% to 0.07% of all patients screened. Surgical procedures for false-positive results were reported in 0.5% to 1.3% of all screened participants.18
In the NLST, false-positive results led to invasive procedures (needle biopsy, thoracotomy, thoracoscopy, mediastinoscopy, and bronchoscopy) in 1.7% of patients screened. Complications occurred in 0.1% of patients screened, and death in the 60 days following the most invasive procedure performed occurred in 0.007 percent of those screened.6 One study evaluated how the use of Lungs-RADS criteria would have affected invasive procedures for false-positive results in the NLST. It estimated that 23.4% of all invasive procedures for false-positive results would have been prevented by using Lung-RADS criteria.16
In the CISNET modeling studies, the false-positive rate varied based on screening eligibility criteria. A program screening adults ages 55 to 80 years who have at least a 30 pack-year history and currently smoke or have quit within the past 15 years (A-55-80-30-15) would result in 1.9 false-positive results per person screened over a lifetime of screening, and a program screening adults ages 50 to 80 years who have at least a 20 pack-year history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would result in 2.2 false-positive results per person screened.11 Note that screening programs that start at a younger age or use a lower pack-year eligibility would screen a larger total number of persons.
Determining the rate of overdiagnosis in screening trials is challenging because calculations of excess cancers (i.e., potentially overdiagnosed cancers) are influenced by the duration of followup. In the initial publication of the NLST, an excess of 119 lung cancers were reported after three screening rounds and 6.5 years of followup (1,060 total cancers from the LDCT group and 941 from the chest x-ray group; calculated IRR, 1.12 [95% CI, 1.02 to 1.22]).6, 18 With extended followup, the NLST reported no statistically significant difference between groups for overall lung cancer incidence; however, this study had some methodologic limitations, including use of a different ascertainment method during posttrial followup, lack of information on any posttrial screening that may have occurred in either the LDCT or chest x-ray group, and missing data.29 In the NELSON trial, 40 excess lung cancers were reported in the LDCT group after 10 years of followup since randomization, the a priori planned followup duration (344 cancers in the LDCT group and 304 in the control group); after 11 years of followup, there was an excess of 14 cancers.8 The Italian Lung Cancer Screening Trial (ITALUNG) reported a similar number of lung cancers in the screening and control groups after 5 years of followup, suggesting that there was no overdiagnosis in the screening group after adequate followup.30
In the CISNET modeling studies, which account for lifetime followup, a program screening adults ages 55 to 80 years who have at least a 30 pack-year history and currently smoke or have quit within the past 15 years (A-55-80-30-15) would result in 6.3% of screen-detected cases of lung cancer representing overdiagnosed lung cancer, and a program screening adults ages 50 to 80 years who have at least a 20 pack-year history and currently smoke or have quit within the past 15 years (A-50-80-20-15) would result in a 6.0% proportion of lung cancers being overdiagnosed.11
Three trials and six cohort studies reported on radiation associated with LDCT.18 Most reported on the radiation exposure associated with one LDCT scan, with ranges from 0.65 to 2.36 mSv. For context, average annual background radiation exposure in the United States is 2.4 mSv. Two of the studies estimated the cumulative radiation exposure for participants undergoing screening with LDCT. The ITALUNG trial estimated a lifetime risk of fatal cancer of 0.11 cases per 1,000 persons for LDCT after the four screening rounds.31 Data from the Continuing Observation of Smoking Subjects study estimated the lifetime risk of cancer from radiation of 10 annual LDCT scans was 2.6 to 8.1 major cancers per 10,000 persons screened.32
The CISNET modeling studies found that lifetime estimates of radiation-related lung cancer deaths varied by eligibility criteria for screening. In a program screening adults ages 55 to 80 years who have at least a 30 pack-year history and currently smoke or have quit within the past 15 years (A-55-80-30-15), there would be an estimated 20.6 radiation-related lung cancer deaths per 100,000 persons in the total population ages 45 to 90 years, or 1 death caused for every 18.5 lung cancer deaths avoided (or 237 life-years gained) by screening. In a program screening adults ages 50 to 80 years who have at least a 20 pack-year history and currently smoke or have quit within the past 15 years (A-50-80-20-15), there would be an estimated 38.6 radiation-related lung cancer deaths per 100,000 persons in the total population ages 45 to 90 years, or 1 death caused for every 13.0 lung cancer deaths avoided (or 179 life-years gained) by screening.11
When comparing LDCT groups vs. control groups for smoking cessation or abstinence outcomes, evidence does not indicate that screening leads to lower rates of smoking cessation or continued abstinence, or to higher rates of relapse. Several studies suggest that, compared with no screening, individuals who receive LDCT screening do not have worse health-related quality of life, anxiety, or distress over 2 years of followup. However, screening participants who receive true-positive or indeterminate results may experience worse health-related quality of life, anxiety, or distress in the short term.18
Studies reported a wide range of screening-related incidental findings that were deemed significant or required further evaluation (4.4% to 40.7%), in part because there was no consistent definition of what constitutes an incidental finding nor which findings were clinically significant.18 Older age was associated with a greater likelihood of incidental findings. Common incidental findings included coronary artery calcification, aortic aneurysms, emphysema, and infectious and inflammatory processes. Other common findings were masses, nodules, or cysts of the kidney, breast, adrenal gland, liver, thyroid, pancreas, spine, and lymph nodes. Cancers involving these organs were ultimately diagnosed in 0.39% of NLST participants in the LDCT group during the 4-year screening period.
Incidental findings led to downstream evaluation including consultations, additional imaging, and invasive procedures with associated costs and burdens. The benefits of incidental detection of non-lung cancer conditions and the balance of benefits and harms of incidental findings on LDCT screening remain uncertain.
How Does Evidence Fit With Biological Understanding?
Lung cancer is a proliferation of malignant cells that originate in the tissues of the lung. Smoking is the strongest risk factor for lung cancer. Older age is also associated with increasing incidence of lung cancer. Lung cancer is classified into two major categories based on cell type and immunohistochemical and molecular characteristics: 1) NSCLC, which collectively comprises adenocarcinoma, squamous cell carcinoma, and large cell carcinoma, and 2) small-cell lung cancer. Screening is aimed at early detection of NSCLC rather than small-cell lung cancer because the latter is much less common and typically spreads too quickly to be reliably detected at an early, potentially curable stage by screening.
Currently, 79% of patients present with lung cancer that has spread to regional lymph nodes or metastasized to distant sites. Only 17% of patients present with localized disease. Patients with localized disease have a 59% 5-year survival rate, compared with 32% for those with regional spread and 6% for those with distant metastases (1). By leading to earlier detection and treatment, screening for lung cancer can give patients a greater chance for cure.
- Implementation research addressing how best to increase the uptake of lung cancer screening discussions in clinical practice is needed, particularly among minority and vulnerable populations.
- Research is needed to evaluate whether, as lung cancer screening is implemented in more diverse community settings, including among racial/ethnic minorities, among socioeconomically disadvantaged populations (where smoking prevalence and lung cancer incidence is higher), and in settings that screen greater numbers of women, the balance of benefits and harms differs from that found in RCTs.
- Research to identify biomarkers that can identify persons at high risk is needed.
- Research to identify technologies that can help more accurately discriminate between benign and malignant lung nodules is needed.
- Research is needed on the benefits and harms of using risk prediction models to select patients for lung cancer screening, including whether use of risk prediction models represents a barrier to wider implementation of lung cancer screening in primary care.
The American Association for Thoracic Surgery recommends annual lung cancer screening with LDCT for North Americans ages 55 to 79 years with a 30 pack-year history of smoking. It also recommends offering annual lung cancer screening with LDCT starting at age 50 years to persons with a 20 pack-year smoking history if there is an additional cumulative risk of developing lung cancer of 5% or greater over the following 5 years.33
The American Cancer Society recommends annual lung cancer screening with LDCT for persons ages 55 to 74 years who are in fairly good health, have at least a 30 pack-year smoking history, and currently smoke or have quit within the past 15 years. It also recommends smoking cessation counseling for current smokers, shared decision making about lung cancer screening, and that screening be conducted in a high-volume, high-quality lung cancer screening and treatment center.34
The American College of Chest Physicians guideline and expert panel report suggests annual screening with LDCT should be offered to asymptomatic smokers and former smokers ages 55 to 77 years who have smoked 30 pack-years or more and either continue to smoke or have quit within the past 15 years. It also recommends that screening not be performed for individuals with comorbidities that adversely influence their ability to tolerate the evaluation of screen-detected findings or tolerate treatment of an early-stage screen-detected lung cancer, or that substantially limit their life expectancy.35
The National Comprehensive Cancer Network recommends annual screening for lung cancer with LDCT in persons ages 55 to 77 years who have at least a 30 pack-year smoking history and currently smoke or have quit within the past 15 years, or in persons age 50 years or older who have at least a 20 pack-year smoking history and have at least one additional risk factor for lung cancer.36
The American Academy of Family Physicians has concluded that the evidence is insufficient to recommend for or against screening for lung cancer with LDCT in persons at high risk for lung cancer based on age and smoking history.37
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|Detection||The USPSTF found adequate evidence that LDCT has sufficient sensitivity and specificity to detect early-stage lung cancer.|
|Benefits of Early Detection and Intervention and Treatment||The USPSTF found adequate evidence that annual screening for lung cancer with LDCT in a defined population of high-risk persons can prevent a substantial number of lung cancer–related deaths.|
|Harms of Early Detection and Intervention and Treatment||
|USPSTF Assessment||The USPSTF concludes with moderate certainty that annual screening for lung cancer with LDCT is of moderate net benefit in persons at high risk for lung cancer based on age, total cumulative exposure to tobacco smoke, and years since quitting smoking.|