Incidentally-Detected Lung Cancer in Persons Too Young or Too Old for Lung Cancer Screening in a Mississippi Delta Cohort.

INTRODUCTION: Lung cancer risk in screening age-ineligible persons with incidentally-detected lung nodules is poorly characterized. We evaluated lung cancer risk in two age-ineligible Lung Nodule Program (LNP) cohorts.

METHODS: Prospective observational study comparing 2-year cumulative lung cancer diagnosis risk, lung cancer characteristics and overall survival (OS) between low-dose CT (LDCT) screening participants aged 50-80 years and LNP participants aged 35 - <50 years (young) and >80 years (elderly).

RESULTS: From 2015 to 2022, lung cancer was diagnosed in 329 (3.43%), 39 (1.07%) and 172 (6.87%) LDCT, young and elderly LNP patients, respectively. Two-year cumulative incidence was 3.0% (95% CI: 2.6%-3.4%) versus 0.79% (CI: 0.54%-1.1%) versus 6.5% (CI: 5.5%-7.6%), respectively, but lung cancer diagnosis risk was similar between young LNP and Lung-RADS 1 (aHR 0.88 [CI: 0.50-1.56]) and 2 (aHR 1.0 [0.58-1.72]). Elderly LNP risk was greater than Lung-RADS 3 (aHR 2.34 [CI: 1.50-3.65]), but less than 4 (aHR 0.28 [CI: 0.22-0.35]). Lung cancer was stage I/II in 62.92% of LDCT versus 33.33% of young (p=0.0003) and 48.26% of elderly (p=0.0004) LNP cohorts; 16.72%, 41.03% and 29.65%, respectively were diagnosed at stage IV. Aggregate 5-year OS rates were 57% (CI: 48-67), 55% (CI: 39-79) and 24% (CI: 15-40) (Log-rank p<0.0001). Results were similar after excluding persons with any history of cancer.

CONCLUSION: LNP modestly benefited persons too young or old for screening. Differences in clinical characteristics and outcomes suggest differences in biologic characteristics of lung cancer in these three patient cohorts.