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.