Postoperative radiotherapy-induced pulmonary leiomyosarcoma in breast cancer: a case report and literature review.

Radiation-induced sarcoma (RIS) is a rare and severe complication of radiotherapy following breast cancer surgery. It is characterized by a long latency period, high malignancy, limited clinical experience in diagnosis and treatment, and substantial individual variation in prognosis. This study reports a case of radiation-related pulmonary leiomyosarcoma that developed more than 20 years after radiotherapy for breast cancer. The tumor harbored a TP53 mutation and showed low PD-L1 expression. Imaging documented rapid tumor progression over a short interval, which rendered radical resection impossible and complicated efforts to improve quality of life. However, the patient attempted to receive multiple treatments-interventional therapy, chemotherapy, targeted therapy, and immunotherapy-but the response was poor, survival was under 10 months, and the patient ultimately died.