Thoracic radiotherapy in a cohort study of patients with metastatic small-cell lung neoplasms.

Abstract

e20093 Background: Thoracic radiotherapy (TRT) for extensive stage small-cell lung cancer (ES-SCLC) patients is controversial. Slotman et al. (2015) demonstrated a 2-year overall survival (OS) benefit for patients who received TRT after chemotherapy (CT) and prophylactic cranial irradiation (PCI), but obtaining a median OS of 8 months (m). We wanted to confirm results of Slotman’s work in a real-world setting with higher doses of TRT. Methods: We retrospectively reviewed 67 patients with ES-SCLC treated between 1995 and 2015, after completing CT administration. Patients with initial brain metastasis and those who rejected PCI were excluded. All of them received PCI. All patients were followed until death. Disease-specific survival (DSS), disease-free survival (DFS) and OS were analyzed and computed with Kaplan-Meier method, groups were compared with log-rank test. Adjusted hazard risk (HR) of death for TRT was estimated through multivariate Cox model. Results: Patients (59 male, 8 female) with median age 64 years (42-79) had a median Karnofsky performance status (KPS) of 80. Twenty-three patients received high doses TRT (mean dose: 45.4 Gy). No significant differences between groups were found in age, gender, KPS, number of metastatic sites, residual thoracic disease or smoke activity. Non-TRT patients had more metastatic lesions. Median OS for TRT-patients was 19.9 m and 11.2 m for non-TRT patients (p = 0.01). DSS was 23.4 m for TRT-patients and 13.5 m for non-TRT patients (p = 0.007). For TRT-patients and non-TRT patients, median DFS were 15.5 and 8.3 m (p = 0.001), respectively. In the multivariate analysis, TRT (p = 0.003, HR 0.35), KPS (p = 0.012, HR 0.95) and residual thoracic disease (p = 0.02, HR 3.30) were independent prognostic factors for survival. The best benefit was obtained for those patients with consolidative TRT (CTRT): OS of 24.7, DSS of 27.4 and DFS of 15.9 m, compared with 13.4 (p = 0.003), 13.9 (p = 0.003) and 8.5 m (p = 0.007), respectively, for patients not treated with CTRT. Conclusions: TRT impacts positively in OS, DSS and PFS and should be administered to ES-SCLC patients who complete CT and PCI. High TRT doses could achieve better results than those described for low TRT doses.