Feasibility and safety of repeat breast-conserving surgery with intraoperative irradiation for local breast carcinoma recurrences: A phase 2 trial

Background and purpose:The RE-IORT prospective, multicenter, single-arm phase II trial (NCT02386371) evaluated the feasibility and safety of repeat breast-conserving surgery (BCS) combined with focal reirradiation using intraoperative radiotherapy (IOReIrr) in patients with locally recurrent breast carcinoma.Patients and Methods: Eligible patients had in-breast recurrence 5 years after whole-breast radiotherapy, with low-risk features (unifocal T1N0, non-lobular histology, grade 1-2, estrogen receptor-positive, HER2-negative).The primary endpoint was the absence of grade 2 breast fibrosis at month 12 post-BCS+IOReIrr, reported using the Common Terminology Criteria for Adverse Events, version 4.0.Secondary endpoints were cumulative incidence of local relapse, local relapse-free/distant metastasis-free/disease-free/overall/mastectomy-free survival, quality of life, definitive cosmetic results and satisfaction. Results: Fifty-three of the sixty-six patients enrolled from January 2015 to April 2018 were retained for the analysis (median follow-up of 59 months).At month 12 post-IOReIrr, 48 patients had not developed breast fibrosis (90.6% [95% CI: 79.3-96.9]).During the follow-up, three patients presented a new local relapse after the second BCS+IOReIrr.The 36-month and 60-month local recurrence-free survival rates were 96.8% [95% CI: 85.2-99.0]and 81.2% [95% CI: 65.2-90.3],respectively.The 36-month and 60-month mastectomy-free rates were 94.2% [95% CI: 83.1-98.1]and 92.3% [95% CI: 80.7-97.0],respectively.Conclusions: Intraoperative reirradiation as part of a second BCS (one-day treatment) is feasible, safe, and well-tolerated in selected patients with late local breast cancer recurrence (i.e.<2 cm.estrogen receptor-positive and node-negative).These findings suggests that shared decision-making between 'one-day treatment' and salvage mastectomy is a safe and viable option.