Case Report: Spatially fractionated radiation therapy for local recurrence after prior radiotherapy in advanced right-sided small cell lung cancer with mediastinal lymph node metastases.

A 63-year-old male patient was admitted to the Affiliated Hospital of Jiangsu University on December 26, 2025, with a diagnosis of local recurrence in the mediastinal metastatic lymph nodes after radiotherapy, four years following the initial diagnosis of right-sided lung cancer. The patient was diagnosed with advanced small cell lung cancer of the right lung (cT3N3M1) and had previously received a combination of radiotherapy, chemotherapy, targeted therapy, and immunotherapy. Despite these treatments, the disease continued to progress, with resistance to both chemotherapy and immunotherapy, accompanied by widespread metastases. Palliative radiotherapy was administered for mediastinal lymph node enlargement starting July 2, 2025 (P_GTVn: 48 Gy/12 Fx). A follow-up CT scan on December 26, 2025, confirmed local in-situ recurrence of multiple mediastinal lymph nodes, accompanied by tracheal and superior vena cava compression and stenosis, indicating progressive disease (PD). From January 6, 2026, the patient underwent Spatially Fractionated Radiation Therapy (SFRT) targeted at the mediastinal metastatic lymph nodes, with a total dose of 30 Gy in 6 fractions, combined concurrently with atezolizumab immunotherapy. After five fractions of radiotherapy, follow-up computed tomography showed that the tumor volume decreased from 146 ml to 27 ml, representing a tumor regression rate of over 80%. Significant relief of left main bronchus compression was observed. No obvious radiation-related adverse events were noted during treatment or subsequent follow-up. Long-term efficacy requires further observation and evaluation.