Demographics and outcomes of individuals with young-onset small cell lung cancer.

8104 Background: A diagnosis of lung cancer before the age of 50 is commonly driven by oncogenic alterations and observed in patients without a history of tobacco use. Little is known about the characteristics and outcomes of individuals with young-onset small cell lung cancer (YO-SCLC). Methods: We retrospectively reviewed the charts of patients diagnosed with SCLC treated in the Indiana University (IU) Health System from 2018 to 2024. Patients were stratified by age <50 or >50 years at diagnosis of SCLC for statistical comparison of key variables and outcomes. Fisher’s exact and Wilcoxon rank sum tests were applied to categorical and continuous variables, respectively. Results: Among 416 individuals with SCLC, we identified 23 patients with YO-SCLC. The incidence of YO-SCLC was 5.5 cases per 100 cases of SCLC (95% CI, 3.7-8.2) with a median age of 47 (40-49). None of the YO-SCLC were detected by lung cancer screening (LCS), compared to 17% in the >50 cohort (Table 1). Patients with YO-SCLC are more likely to have active tobacco use but significantly less pack years, compared to >50. Majority of YO-SCLC (74%) were diagnosed with extensive-stage SCLC, analogous to >50. Extensive-stage YO-SCLC patients had similar platinum-sensitivity and PFS with platinum-based therapy with or without immunotherapy but trended to have improved median OS (24.7 vs 11.1 months, HR 1.67, 95% CI 0.88-3.15, P = 0.12). Limited-stage YO-SCLC patients were more likely to receive prophylactic cranial irradiation (PCI, 67% vs 25%, P = 0.04) but demonstrated no significant difference in PFS or OS with guideline-directed therapy, compared to >50. Conclusions: YO-SCLC represents a unique under-recognized population with trends toward improved OS, despite comparable platinum-sensitivity and PFS with chemoimmunotherapy for ES-SCLC. Such patients are currently excluded from LCS due to age. These results suggest eligibility criteria for LCS could be expanded to include individuals <50 with active tobacco use (>20 PY) and a family history of lung cancer to increase detection of YO-SCLC. The molecular underpinnings of YO-SCLC remain to be elucidated. Investigation into the genomic and neuroendocrine subtype composition of YO-SCLC is underway. Characteristic Age <50 (n = 23) Age >50 (n = 393) Overall (n = 416) P value Sex (female) 15 (65%) 231 (59%) 246 (59%) 0.7 Stage (ES-SCLC) 17 (74%) 257 (65%) 274 (66%) 0.5 BMI 33 (23, 38) 27 (23, 32) 27 (23, 32) 0.046 COPD 7 (30%) 207 (53%) 214 (51%) 0.052 Current tobacco use 20 (87%) 247 (63%) 267 (64%) 0.025 Pack years 30 (25, 50) 45 (30, 60) 45 (30, 60) 0.043 Eligible for lung cancer screening 0 (0%) 301 (77%) 301 (72%) <0.001 Detected by lung cancer screening 0 (0%) 68 (17%) 68 (16%) 0.021 +FH lung cancer 9 (39%) 103 (26%) 112 (27%) 0.14