Radiation-Induced Pneumonitis Following Stereotactic Body Radiation Therapy for Left Upper Lobe Squamous Cell Carcinoma.

Abstract

This report describes the case of a 67-year-old male with a history of treated prostate cancer who developed a left upper lobe (LUL) squamous cell carcinoma, which was treated with stereotactic body radiation therapy (SBRT). After SBRT, radiation pneumonitis together with tumor regression led to bronchial obstruction and post-obstructive volume loss that culminated in a rare complete left lung collapse, underscoring an uncommon but serious complication of SBRT. The patient presented with progressive shortness of breath; imaging demonstrated post-obstructive volume loss and heterogeneous FDG avidity consistent with radiation pneumonitis. Corticosteroids were initiated, and symptoms stabilized over the ensuing weeks. The case highlights the need for close surveillance for radiation-induced lung injury, especially in patients with chronic obstructive pulmonary disease and a substantial smoking history. Careful patient selection and structured post-treatment imaging remain essential when SBRT is used for non-small cell lung cancer. Future work should identify predictive biomarkers and mitigation strategies for high-risk patients.