High-Dose-Rate Brachytherapy Combined with Immunotherapy for Advanced Poorly Differentiated Pulmonary Sarcomatoid Carcinoma: A Case Report and Literature Review

The background of this paper is Pulmonary sarcomatoid carcinoma (PSC) is a rare and aggressive subtype of non-small cell lung cancer that is resistant to conventional treatments. High-dose-rate (HDR) combined with immune checkpoint inhibitors (ICIs) may be a promising treatment modality for advanced PSC. The main situation of the case is about a 56-year-old male with advanced poorly differentiated PSC with brain metastasis (T4N2M1b, stage IVA) received cranial radiotherapy and two cycles of platinum-based chemotherapy, followed by HDR brachytherapy (30 Gy in a single fraction) to the left lung tumor using an iridium-192 source. Partial remission was achieved after subsequent treatment with atezolizumab, an immune checkpoint inhibitor. He maintained a progression-free state for nearly 30 months until experiencing progression of intracranial lesions, while the lung lesions remained in partial remission. This case demonstrates the potential synergistic effects of combining HDR brachytherapy with immunotherapy in treating advanced PSC. The durable response observed highlights the rationale for further exploration of this innovative therapeutic strategy. Prospective studies are needed to validate these findings and optimize treatment approaches.