The benefit of radiotherapy in distant metastatic small-cell lung cancer: A retrospective study based on propensity score matching (PSM)

Due to extensive tumor spread, systemic chemotherapy is the main treatment for distant metastatic small-cell lung cancer (DM-SCLC). It is still unclear whether adding local radiotherapy (RT) on the basis of chemotherapy can improve the long-term survival of patients with DM-SCLC. This study aims to explore the population with DM-SCLC who can benefit from RT. Patients with metastatic SCLC with complete data were collected from the Surveillance, Epidemiology, and End Results database and divided into 2 groups according to whether RT was given or not. The propensity score matching method was used to balance the covariate differences between the RT group and the non-RT group. Lasso Cox regression model and Cox proportional hazards regression analyses were used to identifying independent risk factors affecting survival. Kaplan-Meier method was used to calculate the survival rate. P < .05 was considered statistically significant. After matching, there were 3150 patients in both groups. Sex, tumor size, N stage, RT, chemotherapy, brain metastasis, liver metastasis, age, and site metastasis were independent factors of survival in DM-SCLC. The 1- and 2-year survival rates were 24.5% and 5.8% in the RT group and 14.8% and 2.3% in the non-RT group (P < .001). The median survival time of the RT group was 9 months, and that of the non-RT group was 7 months, and the difference was statistically significant (P < .001). RT improved survival in all sex subgroups, any N stage subgroup, any tumor size subgroup, no brain metastases subgroup, no liver metastases subgroup, any age subgroup, and 1-2 organ metastases subgroup. RT improves 1- and 2-year survival in DM-SCLC.