Once-weekly hypofractionated radiotherapy for breast cancer: First results of a phase II clinical trial.

Hypofractionated radiotherapy (HF) in 15 or 16 daily fractions is well established as an alternative in early breast cancer after breast-conserving surgery. Evidences for a whole-breast treatment even shorter, in 5-10 fractions, are still scarce. Women 50 years or older, with early breast tumor (pT1-2pN0), after breast-conserving surgery were eligible to enter in this phase II trial and received whole breast once-weekly hypofractionated radiotherapy (wHF-RT) to a total dose of 30 Gy, in 5 fractions of 6 Gy. During treatment and in post-treatment follow-up the toxicity was assessed and graduated according to the "Common Terminology Criteria for Adverse Events" (CTCAE), v3.0. Breast pictures for esthetic comparison were taken in 5 timepoints and 2 breast surgeons independently graduated the cosmetics changes. The trial was registered with ClinicalTrials.gov, number NCT01965483. From October 2013 to November 2015, 44 patients were enrolled in the trial and treated according to the protocol of wHF-RT. The median age was 70.5 years (51-88 years), and the median follow-up was 22 months (9-33 months). Skin erythema was the most common acute adverse event. At the end of radiation, 30 patients (68.2%) had any grade of radiation dermatitis. Concerning cosmetic appearance, there was no significant difference between pretreatment and 1 year assessments. The 2-year overall survival and disease-free survival were, respectively 96.8% and 97.7%. There was only one distant recurrence and no local or regional recurrence. Once-weekly hypofractionated radiotherapy is a feasible and well tolerated alternative for early breast cancer adjuvant management with acceptable acute toxicity and esthetic outcomes.