Screening for Lung Cancer with Computed Tomography: Systematic Reviews on Effectiveness and Patient Preferences

Purpose: We systematically reviewed the evidence for three questions on screening for lung cancer with computed tomography (CT): benefits (from randomized trials) and harms of screening versus no screening/minimal intervention or alternative screening approaches (e.g., selection criteria, screening intervals); relative importance that informed patients place on the potential benefits and harms of screening (patient preferences); and comparative effects from observational studies of different screening selection criteria (using risk prediction models) or nodule classification systems compared with those used in the screening trials. Methods: A working group of primary care and specialist clinicians (previously members of Canadian Task Force on Preventive Health Care) and topic experts provided input into the eligibility criteria and key potential effect moderators, rated outcomes for their importance to decision making, and developed decision thresholds for use when making conclusions and assessing certainty of the evidence. Critical outcomes of screening effects included all-cause mortality, lung-cancer mortality, and overdiagnosis (via excess cancer incidence from screening). For patient preferences, we sought direct preference data via (i) disutilities of relevant health states (measuring their impact on ones health-related quality of life on a scale of 0 [perfect health] to 1 [death], mainly using EQ-5D), and (ii) other preference-based data, such as outcome trade-offs, as well as indirect preference data via (iii) the relative importance of benefits versus harms inferred from attitudes, intentions, and behaviors towards screening among eligible patients informed with estimates of the outcomes. For screening benefits and harms and for patient preferences, we searched three databases (MEDLINE, Embase, and Central & MEDLINE, Scopus, and EconLit, respectively) to July 11, 2025. For screening studies published prior to 2015 we relied on searches for other reviews, and for patient preferences our search was limited to 2012-onwards. For comparative effects, we searched MEDLINE and Embase from 2019 to September 23, 2025, with reliance on other reviews for studies published 2012-2018. Reference lists were scanned and trial registries searched. For the main searches, two independent reviewers screened titles and abstracts and then full texts; for search updates we applied AI to assist with title and abstract screening. Data extraction and analysis were undertaken by single reviewers, with verification; risk of bias and GRADE certainty assessments were undertaken independently by at least two reviewers. Data were pooled where suitable using random effects methods appropriate to the outcome metric and prevalence. Subgroup analyses explored heterogeneity (e.g., sex, number of rounds, type of comparator, sensitivity of nodule management, type of utility measurement). When not pooled (e.g., patient preferences based on screening intentions) data were analyzed by grouping studies based on factors such as population, setting, exposure, and outcomes, with consideration of study size and risk of bias. Conclusions and certainty assessments for screening effects were based on estimates of absolute effects. Results: We included 85 studies (N=640,537; 13 trials) on screening benefits and harms, 59 on patient preferences (33 [N=42,219] on disutilities and 26 [N=10,829] other studies), and 16 for comparing trial (National Lung Screening Trial [NLST]) and LungRADs nodule management, either directly (2 studies, N=26,978) or indirectly (14 studies, N=1,102,285). Screening benefits and harms: Findings from nine trials (N=94,530) examining low-dose CT (LDCT) screening on all-cause (RR 0.97, 95% CI 0.93 to 1.01; 3.7 fewer [8.5 fewer to 1.2 more] per 1000) and lung-cancer mortality (RR 0.87, 95% CI 0.79 to 0.96; 4.0 fewer [1.2 to 6.4 fewer] per 1000) offered low and moderate certainty, respectively, that screening previous/current 20-30 pack-year smokers 50-74 years old 3-4 times will probably result in at least 1 (all-cause) and 2 (cause-specific) fewer deaths per 1000 screened after 10-12 years. The absolute effects may not apply to participants at the lowest baseline risk for lung-cancer incidence (e.g., <1.5% over 6 years) or death. Seven trials (N=35,161) contributed to meta-analysis for overdiagnosis (RR 1.19, 95% CI 1.03 to 1.37; 8.4 [1.3 to 16.3] per 1000), and our certainty was moderate that LDCT screening 3-4 times will probably result in at least 2.5 cases of overdiagnosis per 1000 screened over 10 years. For important outcomes, we had high certainty that screening 3-4 times results in at least 75 people per 1000 screened (and probably at least 225) having at least one benign biopsy/false positive, 150 having one or more incidental findings (likely at least 450), and 50 (probably at least 100) having a clinically significant/actionable incidental finding, but probably does not have an important impact on major complications or death from invasive testing among those without cancer. Though undergoing a LDCT scan probably causes little-to-no psychosocial harm, having a positive screening result likely causes at least a small degree of harm (i.e., 4-8% change from baseline), especially for the 10-15% having to undergo invasive procedures where some may experience moderate harm. Among those without cancer, these effects may last for several months while the diagnostic process is underway, though moderate certainty evidence found little-to-no effects remaining after 6 months from diagnostic resolution. Comparative effects: Findings from applying different baseline predicted risks for lung-cancer incidence or mortality to the trial populations (i.e., alternative selection criteria) were considered with the effects from screening benefits and harms. Using LungRADs instead of NLST nodule management (among NLST eligible people) probably reduces the false positive rate substantially (about half), though the number of false positives still exceeded the decision threshold of 75 per 1000 and the effects for benefits or other harm outcomes are not known. Patient preferences: Findings showed little-to-no disutility (i.e., <0.04) from a positive screening test (moderate certainty) or a false positive result (low certainty). Low-certainty evidence found there may be little-to-no disutility from a stage I-IIIA cancer diagnosis (before treatment) but small but important disutilities from a stage IIIB/IV diagnosis, during first-line treatment of any stage (though possibly moderate disutility of about 0.09 for stage IIIB/IV), and after treatment for stage IIIB/IV but not stage I-IIIA (without progression) where effects were inconsistent but indicated that any disutility may not be long-lasting. Findings for stage I-IIIA are likely most relevant for understanding the consequences of overdiagnosis. For stated preferences between outcomes, there was low certainty evidence that a small majority (51-75%) of people may accept 69-122 false positives and at least 1.3 cases of overdiagnosis per prevented lung-cancer death, and think that the reduction in lung-cancer mortality is more important than experiencing one of the relevant harms. After being informed about anticipated benefits and harms from screening (with the largest screening effects shown to those at higher baseline risk), progressively more people preferred screening (mainly via intentions) as the net benefit of screening improved from low [25-50% preferred] to moderate [51-75%] to high [>75%]. Conclusions: This review provides contemporary data on the benefits and harms of LDCT screening after at least a decade of follow-up and makes conclusions based on absolute effects while considering thresholds for decision making. Across the reviews, findings indicate that screening those aged 50-74 years with 3-4 rounds of LDCT will lead to benefits and harms for which a majority, but not all, eligible people probably find acceptable and worthwhile. While current nodule management using LungRADs likely reduces false positives, whether it impacts the benefits of screening is less certain and worth further research. Further, comparative prospective studies are lacking to determine the effects from screening for those not meeting the minimum age (50 years) and smoking history criteria in the trials, despite having an equivalent risk for lung cancer.