Abstract
OBJECTIVE: Assessing the role of radiotherapy on the long-term outcomes in patients with small cell lung cancer (SCLC). METHODS: A total of 6819 patients with SCLC diagnosed histologically from 2011 to 2020 were collected from the Surveillance, Epidemiology, and End Results database. The importance of radiation on overall survival (OS) and cancer-specific survival (CSS) was assessed by a random forest algorithm. The association of radiation with OS and CSS was evaluated by COX regression and subgroup analysis. The survival difference between radiation and non-radiation groups was analyzed by the Kaplan-Meier (KM) method. The conditional survival (CS) and competing risk analyses were performed to evaluate the influence of radiation on CSS. RESULTS: Among all variables, the importance of tumor metastasis to OS and CSS ranked first. COX regression analysis indicated independent association (all P < 0.05) of radiation with OS and CSS in patients with metastasis in the liver, lymphatic, and other sites (not found in bone and brain). KM showed better OS and CSS in the radiation group (vs. non-radiation) in the 3 types of metastases (all P < 0.05). Among 5 metastasis patterns, liver metastasis (LM) was identified as the key pattern to OS and CSS. We found that LM patients with chemotherapy, female, and stage IV can significantly benefit from radiotherapy. However, radiation cannot decrease the incidence of cancer-specific death in male LM patients. CONCLUSIONS: This study determined the importance of radiotherapy on the long-term outcomes of patients. In particular, male LM patients may not benefit from radiotherapy.