Immunotherapy and the sequence relative to survival outcomes in SCLC: Analysis of the National Cancer Database.

e20123 Background: Small-cell lung cancer (SCLC) remains an aggressive malignancy with limited therapeutic progress over the past decades. It remains unclear how the sequence of immunotherapy influences overall survival (OS)in SCLC, we performed a population-based analysis using the National Cancer Database (NCDB) to evaluate its association with survival. Methods: Patients with SCLC diagnosed in the NCDB from 2016 to 2021 were identified to evaluate the impact of immunotherapy on OS. Among patients with ES-SCLC, we conducted subsequent analyses to clarify the relationship between the sequence of immunotherapy and OS in the context of chemotherapy and chemoradiotherapy (CRT). Results: Among 69,820 eligible patients, 9,242 received CRT+immuno, and 11,755 received Chemo+immuno. In the overall population, adding immunotherapy to chemotherapy or CRT was associated with modestly improved survival. In ES-SCLC, immunotherapy was consistently associated with longer survival in both the Chemo and CRT cohort, while addition of immunotherapy didn’t confer benefit in LS-SCLC. Within the ES-SCLC Chemo+immuno cohort, altering the initiated immunotherapy interval (0–90 days) didn’t show any meaningful difference in survival. By contrast, in CRT+immuno cohort, survival showed benefit in a time-dependent pattern: patients who initiated immunotherapy within 4-7 days after CRT had the survival trend, which was consistent with the proposed immune activation window. Conclusions: This real-world analysis suggests that immunotherapy was associated with longer survival in ES-SCLC, CRT+immuno is associated with improved OS with a more obvious survival benefit when ICIs are initiated within 4-7 days after CRT. These findings hint the potential importance of immunotherapy sequence and warrant further prospective validation.