Trends in small cell lung cancer incidence and projections of future burden through 2050.

e20119 Background: Limited studies have explored the population-level incidence of small cell lung cancer (SCLC) in the United States. Given recent demographic changes, including an aging population and increased racial diversity, updated estimates are warranted. Further, understanding the future burden of the disease could guide public policy and health planning. Here, we aim to quantify the most recent epidemiologic estimates of SCLC in the US and estimate the disease trajectory across different demographic groups through 2050. Methods: This retrospective, population-based study utilized data from the Surveillance, Epidemiology, and End Results (SEER 17) database. Adults aged 18-84 years, diagnosed with SCLC based on International Classification of Diseases for Oncology, Third Edition (ICD-O-3) morphology codes 8002, 8041-8045 and site codes C33.9-C34.3, C34.8 and C34.9, were included. Annual age-adjusted SCLC incidence rates per 100,000 persons were calculated. Age-period-cohort models were employed to evaluate incidence trends from 2000 to 2021, with projections through 2050, both overall and stratified by sex, and race/ethnicity. Annual percent change (APC) were calculated using a log-linear Poisson model. Results: A total of 120,128 incident SCLC cases were recorded in the US between 2000 and 2021, with a mean age of 67.0 years (SD = 9.4). Half were male (50.2%), the majority were non-Hispanic White (82.9%) and 8.1% were non-Hispanic Black. Rates of SCLC significantly decreased by -7.7% (95% CI: -12.2, -3.0) with each successive birth cohort independent of age and period. The age-adjusted SCLC incidence per 100,000 decreased from 11.9% (95% CI: 11.6, 12.2) in 2000 to 6.0% (95% CI: 5.8, 6.2) in 2021, corresponding to an APC of -4.3% (95% CI: -4.9, -3.7). When stratified, SCLC incidence decreased at -4.2% (95% CI: -4.8, -3.5) per year in males and -4.3% (95% CI: -5.1, -3.5) in females. Non-Hispanic White adults showed an APC of -3.5% (95% CI: -4.2, -2.9), while non-Hispanic Blacks incidence rates declined by -3.5% (95% CI: -4.4, -2.5). From 2022 to 2050, we forecast that overall incidence rates will decrease at a faster rate (APC: -5.9%; 95% CI: -8.5, -3.5), reaching a nadir of 1,302 (95% CI: 969, 1635) incident cases by 2050. When stratified, the incidence rate is projected to decrease at an APC of -5.5% (95% CI: -8.0, -3.0) in males and -6.2% (95% CI: -8.8, -3.7) in females, non-Hispanic Whites will exhibit an APC of -6.1% (95% CI: -9.1, -3.3), while incidence rates in non-Hispanic Blacks are predicted to decrease by -5.7% (95% CI: -14.6, -2.3). Conclusions: By 2050, the incidence of SCLC is projected to decline at an accelerated rate, with each successive birth cohort exhibiting significantly lower rates. This reduction could be due to a substantial shift in smoking habits, highlighting the importance of tobacco control efforts. Further work is needed to improve the quality of life and survival in this patient population.