Proton and carbon ion radiotherapy for operable early-stage lung cancer; a prospective nationwide registry.

ABSTRACT

BACKGROUND AND PURPOSE: To investigate the toxicity and survival outcomes of proton and carbon ion radiotherapy for patients with operable early-stage lung cancer who are eligible for lobectomy. MATERIALS AND METHODS: This multicenter nationwide prospective cohort study included patients with operable early-stage lung cancer. Proton and carbon ion radiotherapy was performed according to the schedule stipulated in the unified treatment policy. Progression-free survival (PFS), overall survival (OS) and treatment-related toxicities were evaluated. RESULTS: A total of 274 patients were enrolled and included in efficacy and safety analyses. The most common tumor type was adenocarcinoma (44 %), while 105 cases (38 %) were not histologically confirmed or diagnosed clinically. Overall, 250 (91 %) of the 274 patients had tumors that were peripherally situated, while 138 (50 %) and 136 (50 %) patients were treated by proton and carbon ion radiotherapy, respectively. The median follow-up time for all censored patients was 42.8 months (IQR 36.7-49.0). Grade 3 or severe treatment-related toxicity was observed in 4 cases (1.5 %). Three-year PFS was 80.5 % (95 % CI 75.7 %-85.5 %) and OS was 92.5 % (95 % CI 89.3 %-95.8 %). Pathological confirmation and clinical stage were factors significantly associated with PFS, while tumor location and particle-ion type were not. Meanwhile, clinical stage was significantly associated with OS, but pathological confirmation, tumor location, and particle-ion type were not. CONCLUSIONS: Particle therapy for operable early-stage lung cancer resulted in excellent 3-year OS and PFS in each subset. In this disease context, proton and carbon ion beam therapies are feasible alternatives to curative surgery.