Effect and mechanism of local radiotherapy combined with immune checkpoint inhibitor in the treatment of metastatic triple negative breast cancer.

Triple negative breast cancer is highly sensitive to immunotherapy due to its high PD-L1 expression; however, many patients exhibit poor response or develop resistance. This study evaluates the efficacy and mechanism of local radiotherapy combined with PD 1/PD-L1 inhibitors in metastatic triple negative breast cancer treatment. A retrospective analysis of 40 patients divided into a combination group (local radiotherapy + PD-1/PD-L1 inhibitor) and a single-agent group (PD-1/PD-L1 inhibitor) was conducted. Clinical efficacy, progression-free survival, immune cytokine levels (Tumor necrosis factor-α, Interleukin-1, and Interleukin-8), and adverse effects were compared. Results showed that the combination therapy significantly improved clinical outcomes and prolonged progression-free survival without increasing toxicity. Patients receiving local radiotherapy and PD-1/PD-L1 inhibitors exhibited reduced immune cytokines, with no significant post-treatment increase in Tumor necrosis factor-α, Interleukin-1, and Interleukin-8 levels. These findings suggest that local radiotherapy enhances the effectiveness of PD-1/PD-L1 inhibitors in TNBC treatment without raising the risk of adverse effects.