X Force X32 Exe Smoke 2013
Mazie Wingeier
The USPSTF recognizes that clinical decisions involve more considerations than evidence alone. Clinicians should understand the evidence but individualize decision making to the specific patient or situation.
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.
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 than in 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
The US Preventive Services Task Force (USPSTF) concludes with moderate certainty that annual screening for lung cancer with LDCT has a moderate net benefit in persons at high risk of 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 with serial imaging rather than invasive procedures.
Refer to the Table for more information on the USPSTF recommendation rationale and assessment. For more details on the methods the USPSTF uses to determine the net benefit, see the USPSTF Procedure Manual.6
Smoking and older age are the 2 most important risk factors for lung cancer.3-5 The risk of lung cancer in persons who smoke increases with cumulative quantity and duration of smoking and with age but decreases with increasing time since quitting for persons who formerly smoked.3 The USPSTF considers adults aged 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.
African American/Black (Black) men have a higher incidence of lung cancer than White men, and Black women have a lower incidence than White women.1 These differences are likely related to differences in smoking exposure (ie, prevalence of smoking) and related exposure to carcinogens in cigarettes.7,8 The differences may also be related to other social risk factors.
Low-dose computed tomography has high sensitivity and reasonable specificity for the detection of lung cancer, with demonstrated benefit in screening persons at high risk.9-11 Other potential screening modalities that are not recommended because they have not been found to be beneficial include sputum cytology, chest radiography, and measurement of biomarker levels.12,13
The 2 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.10 The Nederlands-Leuvens Longkanker Screenings Onderzoek (NELSON) trial screened at intervals of 1 year, then 2 years, then 2.5 years.11 Modeling studies from the Cancer Intervention and Surveillance Modeling Network (CISNET)14,15 suggest that annual screening for lung cancer leads to greater benefit than does biennial screening. Based on the available evidence and these models, the USPSTF recommends annual screening.
Available data indicate that uptake of lung cancer screening is low. One recent study using data for 10 states found that 14.4% of persons eligible for lung cancer screening (based on 2013 USPSTF criteria) had been screened in the prior 12 months.18 Increasing lung cancer screening discussions and offering screening to eligible persons who express a preference for it is a key step to realizing the potential benefit of lung cancer screening.
As noted above, the USPSTF recommends annual screening for lung cancer with LDCT in adults aged 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 NLST9 and the NELSON trial11 enrolled generally healthy persons, so 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.
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,19 persons referred for lung cancer screening 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 all screening programs.
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; thus, 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.
The randomized clinical trials (RCTs) that provide evidence for the benefit of screening for lung cancer with LDCT were primarily conducted in academic centers with expertise in the performance and interpretation of LDCT and the management of lung lesions seen on LDCT. 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 to 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.20 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.21
Prevention of initiation of smoking and smoking cessation for those who smoke are the most important interventions to prevent lung cancer. The USPSTF has made recommendations on interventions to prevent the initiation of tobacco use in children and adolescents22 and on the use of pharmacotherapy and counseling for tobacco cessation.19
This recommendation replaces the 2013 USPSTF recommendation on screening for lung cancer. In 2013 the USPSTF recommended annual screening for lung cancer with LDCT in adults aged 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).23 For this updated recommendation, the USPSTF has changed the age range and pack-year eligibility criteria and recommends annual screening for lung cancer with LDCT in adults aged 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). Abbreviations for screening recommendations are expanded in the Box.
As in the 2013 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.
To update its 2013 recommendation, the USPSTF commissioned a systematic review24,25 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 (eg, 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 (eg, 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 variants of the prior USPSTF recommendation criteria.
The USPSTF reviewed several RCTs and cohort studies that reported on the sensitivity, specificity, or predictive value of LDCT, using eventual diagnosis of lung cancer as the reference standard.24,25 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%.
Three retrospective studies compared how various approaches for nodule classification would alter the accuracy of LDCT.21,27,28 The first study demonstrated that using Lung-RADS in the NLST would have increased specificity while decreasing sensitivity.21 The other 2 studies found that use of I-ELCAP criteria (increase in nodule size threshold to an average diameter of 5 mm, 6 mm, or larger) would increase positive predictive value.27,28
The NLST, the largest RCT to date (n = 53,454), enrolled participants aged 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.9 The NELSON trial (n = 15,792) enrolled participants aged 50 to 74 years who had a tobacco use history of at least 15 cigarettes a day (three-fourths of a pack per day) for more than 25 years or 10 cigarettes a day (one-half of 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.11
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