An emerging disparity in young-onset lung adenocarcinoma: Evidence from a SEER analysis.

Abstract

e20677 Background: Lung adenocarcinoma (LUAD) incidence in younger adults has received limited attention, and stage-specific trends across sex and race/ethnicity remain incompletely characterized. We evaluated the temporal incidence patterns and survival outcomes among patients aged 15–49 years, with a focus on identifying emerging demographic subgroups. Methods: Incidence data for LUAD diagnosed between 2000 and 2021 were obtained from the SEER 17 Registries (November 2023 submission). Age-adjusted incidence rates were calculated using the 2000 US standard population and stratified by age group (15–39 vs 40–49), sex, race/ethnicity (non-Hispanic White, non-Hispanic Black, non-Hispanic Asian or Pacific Islander [NHAPI], Hispanic), and SEER Combined Summary Stage (2004+; localized, regional, distant). Temporal trends were assessed using Joinpoint regression to estimate annual percent change (APC). The emerging group was defined a priori as NHAPI females; all other patients comprised the non-emerging group. Survival analyses included cases diagnosed from 2004–2016. Five-year cause-specific survival was estimated using the Kaplan–Meier method, with comparisons by log-rank testing. Multivariable Cox proportional hazards models evaluated associations between demographic and clinical factors and survival. Stage distribution at diagnosis was compared using chi-square testing. Results: Among 11,072 patients aged 15–49 years, 776 (7.0%) comprised the emerging group. Joinpoint analyses demonstrated an increase in LUAD incidence among NHAPI females, particularly in distant-stage disease, while most other demographic groups showed stable or declining trends. Five-year cause-specific survival was significantly higher in the emerging group compared with others (median survival 34.0 vs 18.0 months; log-rank p < 0.001). In multivariable Cox regression, emerging group status was independently associated with improved survival (HR 0.73, 95% CI 0.66–0.80). Advanced stage at diagnosis remained the strongest predictor of mortality (regional: HR 3.59; distant: HR 11.89; both p < 0.001). Despite improved survival, the emerging group demonstrated a higher proportion of distant-stage presentation (71.1% vs 66.7%, p = 0.002). Conclusions: Young NHAPI females represent an emerging subgroup with increasing LUAD incidence and distinct stage and survival patterns. Although survival outcomes were more favorable, a higher burden of advanced-stage disease highlights a growing disparity. These findings underscore the importance of disaggregated analyses to identify emerging at-risk populations and inform targeted prevention and early detection strategies.