NRG Oncology/RTOG 1014: 3 Year Efficacy Report From a Phase II Study of Repeat Breast Preserving Surgery and 3D Conformal Partial Breast Re-Irradiation (PBrI) for In-Breast Recurrence

Abstract Purpose Trial**** is a prospective phase II trial of 3D-CRT PBrI following repeat lumpectomy for in-breast recurrence following previous whole breast irradiation (WBI). The primary goal of the trial was to determine the associated toxicity, tolerance and safety of PBrI. Materials and Methods Eligibility criteria included in-breast recurrence occurring >1 year following WBI, Results Between 2010 and 2013, 65 patients were accrued and the first 55 eligible and with 1 year follow-up were analyzed. Median age is 68 years. 22 patients had DCIS and 33 invasive disease; 19 ≤1cm, 13 >1 to ≤2cm and 1 >2cm. All patients were clinically node-negative. Systemic therapy was delivered in 51%. All treatment plans underwent quality review for contouring accuracy and dosimetric compliance. All treatment plans scored acceptable for tumor volume (TV) contouring and TV dose volume analysis (DVA). Only 4 (7%) scored unacceptable for organs at risk (OAR) contouring and OAR DVA. Treatment-related skin, fibrosis, and/or breast pain AEs were recorded as grade 1 in 64%, grade 2 in 7% with only 1 ( Conclusion PBrI with 3D-CRT following second lumpectomy for patients experiencing in-breast failures after WBI is safe and feasible with acceptable treatment quality achieved. Skin, fibrosis and breast pain toxicity was acceptable and grade 3 toxicity was rare.