Intraoperative Radiation Using Low-Kilovoltage X-Rays for Early Breast Cancer: A Single Site Trial

Two prospective, randomized trials, TARGIT-A and ELIOT, have shown intraoperative radiation therapy (IORT) to be a safe alternative to whole breast radiation therapy following breast-conserving surgery for selected low-risk patients. However, minimal data are available about the clinical effectiveness of this modality of treatment using the Xoft^® Axxent^® Electronic Brachytherapy (eBx^®) System^®.

A total of 201 patients with 204 early-stage breast cancers were enrolled in a prospective X-ray IORT trial from June 2010 to September 2013. All tumors were treated with breast-conserving surgery and IORT. Data were collected at 1 week, 1 month, 6 months, 1 year, and yearly thereafter.

With a median follow-up of 50 months, there have been seven ipsilateral breast tumor events (IBTE), no regional or distant recurrences, and no breast cancer-related deaths. One IBTE was within the IORT field, four outside of the IORT field but within the same quadrant as the index cancer, and two were new biologically different cancers in different quadrants. Three events were in patients who deviated from the protocol criteria. Kaplan-Meier analysis projects that 2.9% of patients will recur locally at 4 years.

Recurrence rates observed in this trial were comparable to those of the TARGIT-A and ELIOT trials as well as the retrospective TARGIT-R trial. The low complication rates previously reported by our group as well as the low recurrence rates reported in this study support the cautious use and continued study of IORT in selected women with low-risk breast cancer.