This retrospective study analyzing 16 patients with locally recurrent breast cancer who underwent re-irradiation to the chest wall with PBT to the median dose of 50.4 CGyE in 28 fractions. With the median follow-up time was 18.7 months, this study reported no local failures observed after re-irradiation. Grade 3-4 acute skin toxicity was observed in 5 (31.2%) patients. Four (25%) patients developed chest wall infections during or shortly (2 weeks) after re-irradiation.

Late grade 3-4 fibrosis was observed in only 3 (18.8%) patients. Grade 5 toxicities were not observed. Pneumonitis, telangiectasia, rib fracture, and lymphedema occurred in 2 (12.5%), 4 (25%), 1 (6.3%), and 1 (6.3%) patients, respectively. This study concludes that re-irradiation with PBT for recurrent breast cancer has acceptable toxicities.br>