Hypofractionated whole breast irradiation after IORT treatment is safe in patients receiving adjuvant chemotherapy.

Introduction: Hypofractionated whole breast irradiation (hWBI) and intraoperative radiotherapy (IORT) could be associated in breast cancer patients showing high-risk factors of local recurrence after breast conserving therapy (BSC). The aim of this trial was to evaluate, for the first time, the toxicity and cosmesis of hWBI after photon-IORT in high-risk patients treated by adjuvant chemotherapy.

Materials And Methods: Thirty-one high-risk localized breast cancer patients treated by BCS, IORT (20 Gy), and adjuvant chemotherapy were included from February 2019 to August 2020 in this prospective trial, of hWBI (40.5 Gy/2.67 Gy/15 fractions). Acute and late toxicity (CTCAEv5.0) and cosmesis (Harvard scale), were assessed after treatment.

Results: All patients completed their treatment and were evaluable after treatment. No patients showed severe (G3) acute/late toxicity. Excellent/good cosmesis at least 6 months after completing the treatment, was present in 93.6% of the patients.

Conclusion: hWBI in high-risk localized breast cancer patients treated by chemotherapy seems to have similar toxicity and cosmetic results than conventionally fractionated WBI in combination to photon-IORT after BCS.