Proton beam therapy is a safe and feasible treatment for patients with second primary lung cancer after lung resection

Background The purpose of the present study was to retrospectively evaluate the safety and efficacy of proton beam therapy (PBT) in patients with second primary lung cancer after lung resection. Methods Patients who were diagnosed with second primary lung cancer after lung resection and underwent PBT between January 2009 and February 2015 were retrospectively recruited. Toxicities were evaluated using Common Terminology Criteria for Adverse Events version 4.0. Results Nineteen patients were eligible for inclusion in this study. All of the patients completed the treatment. The median age was 75 (range: 63–82) years, and the median follow‐up time of living patients was 60 months. The median dose of PBT was 76.8 Gy relative biological effectiveness (range: 66.0–80.0 Gy). The three‐year overall survival rate was 63.2% and the three‐year local control rate was 84.2%. No grade 4 or 5 toxicities were observed after PBT. Conclusions Our results suggest that PBT is a safe and feasible treatment for second primary lung cancer compared to surgery or X‐ray radiotherapy. PBT may become a treatment choice for patients with second primary lung cancer after lung resection.