Abstract
BACKGROUND: Low-dose radiotherapy (LDRT) is a localized irradiation technique that utilizes a relatively low radiation dose, typically ranging from 1 to 5 Gy, which is significantly lower than the dose of 20-60 Gy administered in conventional radical radiotherapy. Chemoimmunotherapy (CIT) is a combined therapeutic approach that integrates chemotherapy and immunotherapy, aiming to improve antitumor efficacy through the synergistic interaction of both modalities. This retrospective study aimed to evaluate the survival outcomes of LDRT combined with CIT vs. CIT alone among small cell lung cancer (SCLC) patients with liver metastasis (LM). METHODS: This retrospective analysis included 74 SCLC patients with LM from our hospital between September 1, 2019 and September 1, 2024. The 74 included patients were divided into two groups: the CIT group and the LDRT + CIT group. Kaplan-Meier analysis was used to estimate the progression-free survival (PFS) and overall survival (OS). Subgroup analyses based on the line of therapy and the number of metastatic organs were also performed via univariate Cox proportional hazards regression analysis. RESULTS: The results revealed that the median PFS of the LDRT + CIT group was longer than that of the CIT group (5.1 months vs. 4.0 months, p = 0.016), and the beneficial effects of LDRT + CIT on PFS were observed across multiple subgroups. Most subgroups did not exhibit improvements in OS. However, when the patients were stratified on the basis of line of therapy, the median OS (11.0 months vs. 6.0 months, p = 0.047) improved in the LDRT + CIT group receiving later-line treatment. CONCLUSION: Among SCLC patients with LM, LDRT + CIT may yield superior survival outcomes compared with CIT alone, particularly when LDRT is administered in later-line therapy and among specific subgroups. The findings of this study offer new treatment options for improving survival and quality of life in this challenging patient population.