Intraoperative Radiation Therapy for Early-Stage Breast Cancer: Updated Outcomes from a Single-Institution Experience

Background. Increasingly, data have supported the use of partial-breast irradiation (PBI) for low-risk patients after breast-conserving surgery, with techniques allowing for completion of treatment in 1-3 weeks. Intraoperative radiation therapy (IORT) is an alternative to PBI. Our institution had used low-energy photon IORT (TARGIT) for more than a decade. The initial results demonstrated a 2% local recurrence rate with a short follow-up period of 2 years. This report presents updated outcomes during with 5-year follow-up.Methods. A review of an institutional review board (IRB)-approved institutional registry was performed. The review identified 215 patients with early-stage breast cancer (stages 0-IIA) who received IORT. At the time of surgery, IORT was delivered with 20 Gy in a single fraction, with 5.1% (n = 11) of patients receiving additional whole-breast irradiation (WBI).Results. The mean age at diagnosis was 71 years (range, 49-98 years), and the median follow-up was 5.7 years (interquartile range [IQR], 4.2-7.0 years). Of the 215 patients, 2.8% (n = 6) had ductal carcinoma in situ (DCIS), 90.7% (n = 195) had T1 disease, and 6.5% (n = 14) had T2 disease. Endocrine therapy was prescribed for 79% and chemotherapy for 1.4% of the patients. The 5-year rates were 5.3% for local recurrence, 6.4% for locoregional recurrence, and 2.7% for distant metastases. At 5 years, 93% of the patients were alive.Conclusions. The 5-year outcomes with TARGIT IORT demonstrated high rates of local recurrence, exceeding those seen with alternative modern approaches. The local recurrence outcomes with IORT are more consistent with studies omitting radiation following breast-conserving surgery, using endocrine therapy alone. Consistent with current guidelines and previous data, TARGIT IORT should not be used as monotherapy outside prospective clinical trials.