Does treatment delay matter?: Impact of time to immunotherapy on survival in extensive-stage small cell lung cancer.

8115 Background: Immune checkpoint inhibitors (ICI) combined with platinum-etoposide chemotherapy are the standard first-line treatment for extensive-stage small cell lung cancer (ES-SCLC) based on the CASPIAN and IMpower133 trials. Given the aggressive nature of ES-SCLC, timely initiation of systemic therapy is critical; however, delays in treatment initiation are common in real-world practice. The impact of time to immunotherapy initiation (TTI) on survival has not been well characterized. Methods: Adult patients diagnosed with EO-SCLC (2019-2021) who received immunotherapy as part of first-line systemic therapy were identified from NCDB. TTI was defined as the time from diagnosis to first immunotherapy and categorized as ≤30, 31–60, or > 60 days. Association between TTI and OS was analysed using multivariable Cox proportional hazards models adjusting for patient and facility-level factors. A 90-day landmark analysis were performed to mitigate immortal time bias. Multivariable logistic regression was used to identify predictors of delayed initiation (> 30 days). Results: A total of 18,630 patients were identified. 2,652 (14.24%) died during follow-up. Median TTI was 29 days (IQR 18–45), with median follow-up of 9.36 months. In multivariable Cox models, TTI was not independently associated with OS (31–60 vs ≤30 days: HR 0.92 0.84–1.00; > 60 vs ≤30 days: HR 1.00 0.89–1.11). Results were consistent in a 90-day landmark analysis. Increasing age was associated with higher mortality (HR 1.01 per year, p = 0.003). Treatment at academic/research programs was associated with better OS (HR 0.71 0.61–0.82), while Medicaid insurance was associated with worse OS (HR 1.31 1.15–1.49). Black patients were more likely to receive delayed treatment (OR 1.31 1.16–1.48) while Asian patients were less likely (OR 0.74 0.55–0.98), when compared with Non-Hispanic White patients. Medicaid (OR 1.36 1.20–1.53) and Medicare insurance (OR 1.10 1.01–1.21) were associated with increased odds of delay versus private insurance. Higher comorbidity burden (Charlson–Deyo score ≥2 vs 0: OR 1.10 1.02–1.19) and treatment at academic centers (OR 1.33 1.17–1.51) were also associated with delay. Higher neighborhood income was protective (highest vs lowest quartile: OR 0.86 0.77–0.95). Conclusions: In a large national cohort of ES-SCLC patients receiving immunotherapy, modest delays in treatment initiation were not associated with OS. However, significant disparities exist in timely access, highlighting opportunities for system-level interventions to improve equity in cancer care delivery.