Three-Fraction External Beam Radiotherapy in Patients with Early Breast Cancer

Patients with early breast cancer (EBC) can be treated with accelerated partial breast irradiation (APBI). The objective of this study was to determine if a three-fraction APBI schedule is feasible for these patients.

This single-institutional, phase 2 study included patients with age ≥45 years, tumor size <3.5 cm, negative nodes, negative surgical margins, and unicentric tumors. Patients were treated with 3D-CRT technique with a dose of 22.5 Gy in 3 fractions on 3 consecutive days. The primary end point of the study was cosmesis as assessed by physicians at 3 years. Secondary end points were cosmesis as assessed by patients, dosimetry, acute and late toxicities, disease-free and overall survival.

From October 2019 to October 2022, 49 patients were treated. Mean age of the patients was 55 years (range 40-75). At 3 years, physician- and patient-reported cosmetic results were excellent/good/fair in 33 (67%)/14 (29%)/2 (4%) of patients and in 29 (59%)/16 (33%)/4 (8%) of patients, respectively. Acute dermatitis grades 1 and 2 were observed in 14 (29%) and 3 (6%) of patients, respectively. At 6 months, breast edema, skin induration, subcutaneous fibrosis, pain, and pigmentation were observed in 3 (6%), 6 (12%), 3 (6%), 2 (4%), and 8 (16%) of patients, respectively. At 3 years, 1 (2%) patient had mild pain; no breast edema, skin induration, subcutaneous fibrosis, or pigmentation was observed. At a median follow-up of 39 months (range 24-60), there were no local/regional recurrences. One patient developed distant metastases in the bones, liver, and lungs at 46 months. All patients were alive at last follow-up.

In patients with EBC, three-fraction APBI is feasible. Physician- and patient-reported cosmesis was excellent/good in 96% and 92% of patients, respectively. Late effects were only grade 1.