The Screening Imperative Lung cancer remains the world's leading cause of cancer-related death, causing approximately 1.8 million deaths in 2022. Since most patients are diagnosed at advanced stages, early detection through screening is the most powerful available tool to shift the mortality curve.
Trial Evidence A Cochrane meta-analysis of landmark randomized controlled trials found that low-dose CT (LDCT) lung cancer screening reduced lung cancer mortality by 20% and overall mortality by 5%, establishing it as a life-saving intervention.
This Review's Scope This invited review narratively synthesizes clinical developments from international lung cancer screening trials, highlighting key lessons and discussing enablers and barriers to effective implementation globally - with particular focus on the Asia-Pacific region.
Complementary Value LDCT screening programs complement therapeutic advances (targeted agents and ICIs for advanced-stage disease) by tackling the problem upstream: finding cancers when they are still surgically curable and survival rates are dramatically higher.
NELSON Trial (Netherlands-Belgium) The landmark NELSON trial demonstrated a significant reduction in lung cancer mortality with LDCT screening, providing the pivotal European evidence base alongside the American NLST trial.
MILD Trial (Italy) The Multicentric Italian Lung Detection study randomized 4,099 participants to annual or biennial LDCT versus control and found a 39% reduction in lung cancer mortality at 10 years (HR 0.61). Crucially, benefit improved beyond 5 years of screening (58% reduction), showing that continued screening yields greater cumulative returns.
Biennial vs. Annual Screening MILD data suggested that biennial screening could save approximately one-third of CT scans while maintaining similar performance indicators - an important finding for program efficiency and cost.
LUSI Trial (Germany) This 2,029-participant trial found a 26% reduction in lung cancer mortality overall (non-significant), but a statistically significant 69% reduction specifically in women (HR 0.31), raising important questions about sex-specific screening strategies.
China's Large-Scale Evidence A Chinese multicentre prospective cohort of over 1 million participants found significant reductions in lung cancer mortality and all-cause mortality with LDCT screening. A subsequent CanSPUC study with inverse probability weighting showed a 31% reduction in lung cancer mortality.
USPSTF Criteria Miss Most Asian Cases A West China Hospital study of 15,996 participants showed that applying USPSTF guidelines alone (designed for heavy smokers) to the Asian population missed 90.8% of lung cancers - a dramatic finding explaining why Asia-specific eligibility criteria that include passive smoking histories are essential.
Taiwan's TALENT Trial This trial demonstrated that LDCT screening in high-risk never-smokers (a large group in Asia due to indoor air pollution, cooking fumes, and different cancer biology) detects a substantial proportion of lung cancers, justifying expansion of eligibility criteria beyond smoking history alone.
Air Pollution as a Risk Factor In Asian settings, outdoor and indoor air pollution, cooking fumes, and radon exposure play significant roles alongside smoking. Screening eligibility criteria that fail to capture these risk factors will miss a large proportion of at-risk individuals.
Participation Rates A US registry analysis of over 1.1 million screenings found that only 22% had repeated annual LDCT and 40% were adherent beyond 24 months - well below the rates needed to achieve projected mortality reductions. Engagement and retention are persistent challenges.
Smoking Cessation Integration Lung cancer screening programs offer a powerful teachable moment for smoking cessation. Evidence shows that integrating cessation support into screening programs improves both cessation rates and long-term participation, creating a multiplier effect on mortality reduction.
Nodule Management Complexity Managing the high rate of screen-detected nodules (17% positive at baseline in some registries) requires standardized protocols (e.g., Lung-RADS) and specialist access. Inconsistent follow-up leads to both overdiagnosis harms and missed cancers.
Health System Infrastructure Implementing quality-assured LDCT programs requires CT scanner access, trained radiologists, multidisciplinary teams for positive-result management, and data registries. These prerequisites are unevenly distributed globally, particularly in low-to-middle income countries.
Stage I Detection Rates US registry data showed that 53.5% of screen-detected cancers were stage I, compared to roughly 20% in the unscreened population - a profound stage shift toward early, surgically curable disease.
Survival Rates by Stage Five-year survival for stage I NSCLC treated surgically exceeds 80-90%, compared to less than 10% for stage IV disease. The stage shift observed in screening programs therefore translates directly into meaningful survival gains at the population level.
UK Lung Cancer Screening Pilot The multicenter UK pilot found that 85.7% of screen-detected cancers were stage I or II, and 83.3% underwent surgical resection as primary treatment - the highest-curative-intent option.
Cancer Stage Distribution Consistency Stage distributions in the US registry closely mirrored those in the NLST trial, confirming that real-world screening programs can replicate trial results when implemented with appropriate quality controls.
Never-Smoker Lung Cancer Never-smoker lung cancer is more common in Asia, women, and populations with high air pollution or radon exposure. Current eligibility criteria exclude most of these patients from screening, representing a major equity gap.
Indigenous and Rural Populations Indigenous populations in Australia and other regions have distinct lung cancer risk profiles and face geographic barriers to screening access. CT scanner availability in rural areas and culturally appropriate outreach are essential for equitable implementation.
Socioeconomic Barriers Screening programs that enroll disproportionately older, female, and currently-smoking patients - as seen in US registry data - may miss the highest-risk individuals who are less health-system-engaged. Targeted outreach to economically disadvantaged and minority groups is needed.
Passive Smoking and Cooking Fumes Chinese guidelines that include passive smoking history identify a large group of never-smokers at elevated risk. West China Hospital data showed that adding these individuals to eligibility increased cancer detection rates significantly in this population.
AI-Assisted Nodule Evaluation AI tools for automated nodule detection and risk classification are being integrated into screening programs to standardize interpretation, reduce radiologist workload, and improve consistency - particularly in settings where specialist radiologist access is limited.
Risk Prediction Models Moving beyond age and pack-year thresholds, multivariable risk models incorporating genetic, environmental, and clinical factors can identify high-risk individuals more precisely and cost-effectively than current eligibility criteria.
Program Quality Metrics Effective LCS programs require quality indicators including participation rates, adherence to follow-up, cancer detection rates, stage distribution, and recall rates that must be monitored and publicly reported to ensure programs achieve expected mortality benefits.
Health Technology Assessment Cost-effectiveness modeling shows LDCT screening is cost-effective at established thresholds in many settings, but resource allocation decisions must consider local infrastructure, competing health priorities, and program implementation costs to determine optimal rollout strategies.