2680 - Long Term Single Institution Clinical Outcomes for Locally Recurrent Breast Cancer Patients Treated with a Second Breast Conserving Surgery and Intraoperative Radiotherapy

A. Swistel¹, J. Ng², M. Lee¹, F. Gregucci², S. Trichter², M. K. Hayes¹, and S. C. Formenti²; ¹Department of Surgery, NewYork-Presbyterian/Weill Cornell Medicine, New York, NY, ²Department of Radiation Oncology, NewYork-Presbyterian/Weill Cornell Medicine, New York, NY

Purpose/Objective(s): Recent reports indicate that at local recurrence some patients can be treated with a second breast conserving treatment (BCT) and partial breast re-irradiation with good cosmesis and clinical outcomes. Often, patients who declined total mastectomy (TM) for BCT will decline TM as a treatment option for their recurrent disease. In 2012, we began offering patients who refused TM a pilot program of a second chance BCT plus single dose intraoperative radiotherapy (IORT). We are reporting their clinical outcomes at a median follow up of 6 years. Materials/

Methods: 171 patients were recruited over a twelve-year period with a median follow-up of 6 years. Institutional guidelines included patient refusal of salvage mastectomy, operability to achieve cosmetic BCT, age over 50, node negative on imaging, and documented unifocal breast only disease. Re-operative sentinel node biopsy and postoperative adjuvant therapy were prescribed as indicated. Patients were followed on a regular semiannual basis with physical exams and breast imaging.
Results: Patient median age at the time of IORT was 72 years old (range 52-87). The median time interval between initial treatment and the second BCT was 15 years (range 2-40). The median tumor size at recurrence was 0.75 cm (range 0.1-3). Histology included invasive ductal carcinoma (IDC) 45%, ductal carcinoma in situ (DCIS) 32%, invasive lobular cancer (ILC) 11%, both IDC and DCIS 8%, and other types 4%. Lymphovascular invasion was present in 6 patients (3.5%). 10 patients (6%) were found to be node positive. Most invasive recurrences were T1 tumors, and 6% were T2 tumors. At a median follow-up of 6 years, 22/171 developed a second local recurrence (13 %). 14 occurred in breast only, were treated with subsequent mastectomy and have remained free of disease. Eight patients also developed metastatic disease.
Conclusion: The experience reported guides selection for optimal patients for BCT+IORT. Based on these findings and exclusion of high-risk histology and node positive disease, it is possible to select a population that will have an acceptable low rate of local recurrence and improvement in the quality of life without the need for radical surgical techniques such as TM.