Long-term outcomes of high-dose (74 GyE) proton beam therapy with concurrent chemotherapy for stage III nonsmall-cell lung cancer.

BACKGROUND To evaluate the long-term outcomes of high-dose (74 GyE) proton beam therapy (PBT) with concurrent chemotherapy for stage III non-small cell lung cancer (NSCLC). METHODS Between July 2007 and March 2018, 45 patients with stage III NSCLC were treated with passive-scattering PBT of 74 GyE and concurrent chemotherapy. Among the 45 patients, the median age was 62 years (range 39-79 years) and 32 patients were men. The clinical stages were stage IIIA in 14 patients and stage IIIB in 31 patients. Thirty-six patients received chemotherapy consisting of cisplatin and vinorelbine. RESULTS The median follow-up time was 42.1 months (range 6.4-127.0 months) for all patients and 63.5 months (range 9.4-127.0 months) for the 12 survivors. The 3- and 5-year overall survival rates were 63.7% and 38.8%, respectively, and the median overall survival was 49.1 months. Over the follow-up period, disease recurrence was observed in 32 (71%) patients. The 3- and 5-year progression-free survival rates were 22.2% and 17.7%, respectively, with a median progression-free survival of 13.1 months. In-field control improved survival and the in-field control rate was better in patients with T0-3 tumors (p = 0.023) and stage IIIA/IIIB-N3 disease (p = 0.030). Dosimetric parameters of the heart and lung were not associated with survival. No grade 4 or 5 acute or late non-hematologic toxicities were observed. CONCLUSIONS Passive-scattering PBT of 74 GyE with chemotherapy showed favorable survival and a low incidence of severe adverse events in patients with stage III NSCLC.