Diabetes Mellitus as an Independent Risk Factor for Unfavorable Prognosis in Patients With Small Cell Lung Cancer.

Type 2 diabetes mellitus (DM) is implicated in cancer development and associated with poor survival in patients with cancer. However, the impact of DM on the outcome of small cell lung cancer (SCLC) remains unknown. This study investigated the correlation between DM and clinical outcomes and long-term prognosis of patients with extensive-stage small cell lung cancer (ES-SCLC). This retrospective cohort study was conducted using the medical records of patients with ES-SCLC treated with immune checkpoint inhibitors (ICIs) and chemotherapy. The demographic and clinical characteristics were retrospectively analyzed. Univariate and multivariate analyses were performed using Cox proportional hazards regression to evaluate the impact of the clinical characteristics on survival. Progression-free survival (PFS) and overall survival (OS) were compared between patients with or without DM. Of the 91 patients with ES-SCLC, 32 were diagnosed with DM before ES-SCLC (35.2%). Patients with DM had significantly shorter median PFS (6 vs. 15 months, p = 0.026) and median OS (12 vs. 22 months, p = 0.013) than those without diabetes, despite receiving comparable chemoimmunotherapy. Multivariate cox regression analysis showed that DM was an independent risk factor for shorter mOS (HR 2.05, 95% CI 1.02-4.13, p = 0.044). Patients with ES-SCLC and comorbid diabetes exhibited significantly shorter OS and PFS compared with those without diabetes. DM serves as an independent adverse prognostic risk factor for ES-SCLC.