Partial-Breast Reirradiation with Intraoperative Radiotherapy (IORT) for Patients Affected By Breast Cancer after Prior Thoracic Radiotherapy

Abstract

Mastectomy is currently recommended for patients suffering of new or recurrent breast cancer after prior thoracic radiation. The normal tissue tolerance does not permit a second full-dose course of whole breast irradiation after a second breast-conserving surgery (BCS). We retrospectively investigated the role of a second BCS followed by intraoperative radiotherapy (IORT) for patients with localized breast cancer and prior thoracic radiation. Twenty-five patients, who declined salvage mastectomy for their breast cancer after prior thoracic radiation, were treated with BCS and IORT between 2009 and 2018. Twenty patients (74%) presented breast cancer local relapse after whole breast irradiation, seven (26%) previously received mantle field irradiation for Hodgkin Lymphoma. All breast tumors/recurrences were T1 and unifocal. IORT was delivered with the low energy X-rays IntrabeamTM device (Carl Zeiss Meditec AG, Oberkochen, Germany), using a single dose of 6 Gy prescribed to a depth of 1 cm from applicator surface (20-21Gy at applicator surface). Local control (LC), mastectomy free survival (MFS), disease free survival (DFS) and overall survival (OS) were estimated by Kaplan-Meier estimator. Treatment-related toxicities were scored by National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The median time from prior thoracic radiation to breast cancer presentation was 14 years (range 6-34). All patients successfully underwent BCS and partial breast reirradiation with IORT without acute toxicity. The median follow-up from IORT was 61 months (range 2-117 months). Two patients with local recurrence underwent salvage mastectomy; among whom one had a second local relapse and started chemotherapy. One patient deceased from brain metastases. No other local or distant relapses were detected. LC, MFS, DFS, and OS at five years were 94%, 92.3%, 88.2% and 94% respectively. No cases of late Grade ≥3 toxicity were registered. In our retrospective experience, BCS with IORT is a feasible option for breast preservation in patients with localized breast cancer / recurrence and prior thoracic radiation. Treatment tolerance was excellent. Prospective trials are required to confirm these preliminary findings.