Severe Checkpoint Inhibitor Pneumonitis and Lung Cancer Recurrence After Carbon-ion Radiotherapy in a Patient with Lung Squamous Cell Carcinoma.

Carbon-ion radiotherapy holds promise for central lung cancer owing to its noninvasiveness and precision. We report a case of lung squamous cell carcinoma treated with neoadjuvant chemoimmunotherapy followed by carbon-ion radiotherapy. The course was complicated by severe checkpoint inhibitor pneumonitis with concurrent Pneumocystis jirovecii pneumonia and subsequent recurrence, highlighting the challenge of managing multimodality toxicities during aggressive local control.