PurposeThe clinical significance of carbon-ion radiotherapy (CIRT) for octogenarians with locally advanced non-small-cell lung cancer (LA-NSCLC) remains unclear. We aimed to evaluate the clinical outcomes of CIRT alone for octogenarians with LA-NSCLC.Materials and methodsWe evaluated 32 patients who underwent CIRT alone between 1997 and 2015. The median age was 82.0 years (range, 80–88 years). In terms of clinical stage (UICC 7th edition), 7 (21.9%), 10 (31.3%), 11 (34.4%), and 4 (12.5%) patients had stage IIA, IIB, IIIA, and ΙΙΙB disease, respectively. The median CIRT dose was 72.0 Gy (relative biological effectiveness), and the median follow-up period was 33.1 months.ResultsAll patients successfully completed CIRT. Regarding grade ≥ 2 toxicities, 1 (3.1%), 3 (9.4%), and 4 (0.7%) patients developed grade 3 radiation pneumonitis, grade 2 radiation pneumonitis, and grade 2 dermatitis, respectively. No grade ≥ 4 toxicities were observed. The 2 year LC, PFS, and OS rates were 83.5%, 46.7%, and 68.0%, respectively.ConclusionCIRT alone is safe and effective for octogenarians with LA-NSCLC.