Abstract
<title>Abstract</title> <p> <bold>Background:</bold> This study assessed how treatment intensity and timing affect survival in elderly extensive-stage small cell lung cancer (ES-SCLC) patients, explored survival heterogeneity across clinical subgroups, and built a prognostic nomogram for personalized risk stratification. <bold>Methods:</bold> We extracted 7,053 patients aged ≥65 diagnosed with ES-SCLC (2010–2022) from the Surveillance, Epidemiology, and End Results (SEER) database . Propensity score matching (PSM) balanced baseline confounders across treatment intensity and timing groups. Kaplan-Meier and Cox models analyzed overall survival (OS) and cancer-specific survival (CSS). Independent predictors from the training cohort formed a nomogram validated internally. <bold>Results:</bold> After PSM, patients receiving combined chemoradiotherapy had longer median OS than those receiving lower-intensity treatment (11.0 vs. 9.0 months; log-rank P < 0.001). Subgroup analyses showed that among patients with low metastatic burden, lower-intensity treatment was associated with worse survival compared with combined chemoradiotherapy (HR = 1.45, 95% CI: 1.38-1.53; P < 0.001), whereas no significant difference was observed among those with high metastatic burden (HR = 1.05, 95% CI: 0.88-1.25; P = 0.597). Treatment initiation at 30 days or later after diagnosis was associated with longer observed survival. <bold>Conclusions:</bold> Chemoradiotherapy’s survival advantage differs by metastatic burden in elderly ES-SCLC. High-burden patients obtain no obvious extra survival gain from intensive treatment, supporting individualized care for this frail group. Delayed treatment does not worsen survival. Our nomogram facilitates risk stratification and therapeutic consultation, though external validation is still needed. </p>