Adjuvant proton-based radiotherapy (RT) following breast-conserving surgery showed favorable patient-reported cosmetic outcomes and was considered well tolerated, according to results of a recent study. These results were reported in the journal Clinical Breast Cancer.

“Given optimal cosmesis is critical for patient satisfaction, an understanding of all factors contributing to cosmetic outcomes is important,” the researchers who conducted the study wrote in their report.

The study was a retrospective analysis of records from a large US-based academic center. Included patients had breast cancer that was treated with adjuvant proton-based RT between 2015 and 2020, and for whom breast-conserving surgery had been performed. Toxicity outcomes and patient-reported cosmetic outcomes were evaluated in this study.

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The study included 21 patients who underwent adjuvant proton-based RT. The median whole breast dose received totaled 46.8 Gy (range, 40.0 to 50.4). In 81% of the patients, target volumes involved regional lymph nodes. A median 10-Gy (range, 10 to 14) lumpectomy boost had also been given to 81% of the patients.

By planning target volume, the median V95, V100, and V110 values were 94% (range, 77% to 100%), 71% (range, 60% to 97%), and 2% (range, 0% to 18%), respectively. The median maximum point dose was calculated to be 115% (range, 105% to 120%). Median ipsilateral breast V105 and V110 values were 367.3 cc (range, 0 to 1172) and 24.1 cc (range, 0 to 321.3), respectively.

Patients had a median follow-up period for cosmetic assessment of 27 months (range, 5 to 42). In this evaluation, 79% of patients considered the cosmetic outcome to be good or excellent, with the other 21% considering the cosmetic outcome to be fair. There were no patients reporting a poor cosmetic outcome.

Grade 2 acute radiation dermatitis was observed in 62% of patients, and 14% reportedly had grade 3 dermatitis. Grade 2 pain occurred in 33% of patients, with grade 3 pain occurring in 10%. Grade 2 fatigue was also reported in 33%, and acute esophagitis occurred in a single patient. Among patients with grade 3 acute dermatitis, the cosmetic outcome was considered good by 2 patients and fair by 1 patient.

“In a cohort of breast cancer patients treated with breast-conserving surgery followed by proton-based RT, acute toxicity rates were acceptable and good-to-excellent patient-reported cosmetic outcomes were high,” the researchers concluded in their report.


Sayan M, Kilic S, Zhang Y, et al. Early toxicity and patient-reported cosmetic outcomes in patients treated with adjuvant proton-based radiotherapy after breast-conserving surgery. Clin Breast Cancer. 2023;23(2):176-180. doi:10.1016/j.clbc.2022.11.009