Thoracic Radiation on Survival in Patients with Advanced Small Cell Lung Cancer Treated with Chemoimmunotherapy

BACKGROUND Thoracic radiation therapy (TRT) is known to enhance the prognosis of patients with advanced stage small-cell lung cancer (AS-SCLC) following chemotherapy. This retrospective study aimed to compare outcomes of patients with AS-SCLC treated with chemotherapy and immunotherapy, with and without TRT. MATERIAL AND METHODS We included AS-SCLC cases at our institute confirmed by histopathology and receiving chemoimmunotherapy. Among them, 60 patients received TRT, while 112 did not. The primary study endpoints were progression-free survival and overall survival. We minimized selection bias by using propensity score matching, which was performed using a 1: 1 ratio with a caliper of 0.02, incorporating variables including sex, bone metastases, and total stage. Kaplan-Meier analysis and the log-rank test were applied to assess survival. Univariate and multivariate Cox proportional hazard regression models were performed to evaluate the independent prognostic factors. Subgroup analyses were conducted to identify the potential factors on TRT. RESULTS The median follow-up duration was 20.1 months. Patients who underwent TRT, compared with those that did not, had longer overall survival (24.2 vs 15.9 months, P=0.006) and progression-free survival (11.3 vs 6.6 months, P<0.001). Multivariate Cox regression analysis identified TRT as a favorable prognostic factor for overall survival and progression-free survival (P=0.005 and P<0.001). Subgroup analyses revealed patients without brain or bone metastasis can benefit from TRT (P<0.001). CONCLUSIONS TRT was associated with improved overall and progression-free survival in patients with AS-SCLC receiving chemoimmunotherapy. Prospective randomized trials are warranted to validate these findings.