Intraoperative radiation therapy (IORT)for1200 early breast tumors

ABSTRACT

Introduction: Two prospective randomized trials, TARGIT-A and ELIOT, have shown intraoperative radiationtherapy (IORT) to be a safe alternative with a low-risk of local recurrence compared to whole breast radiationtherapy following breast conserving surgery for selected low-risk patients. We report the first 1200 tumors treatedwith this modality at our facility. Methods: 1200 distinct breast cancers in 1169 patients (31 bilateral) were treatedwith breast conserving surgery and X-ray IORT, using the Xoft Accent System from June 2010 to November 2018.Patients were enrolled in an IORT registry trial and data were collected at 1 week, 1 month, 6 months, 1 year, andyearly thereafter. The primary endpoint was local recurrence. Results: To date, there have been 61 events in 54patients 50 ipsilateral local recurrences (14 DCIS and 36 invasive), 7 regional nodal recurrences and 4 distantrecurrences. Of local recurrences, 9 were within the IORT field, 21 outside of the IORT field but within the samequadrant as the index cancer, and 20 were new cancers in different quadrants. There has been no breast cancerrelated deaths and 27 non-breast cancer deaths. Currently, with a median follow-up of 52 months, Kaplan Meieranalysis projects 5.2 % local recurrence rate at 5 years. In the table below, the five-year probability of localrecurrence is analyzed by quadrant and/or type of recurrence (all recurrences or just invasive). Using the 2017,ASTRO Categories, 520 patients (43%) were suitable for IORT, 415 (35%) were cautionary, and 265 (22%) wereunsuitable for IORT after final histopathology was evaluated. Conclusion: IORT is profoundly convenient. Whenused as the only adjuvant breast irradiation, it eliminates approximately 15-35 outpatient visits. This has become increasingly important during the current COVID-19 pandemic. In the group of patients described here, more that100,000 patient-hours were saved. The local, regional, and distant recurrence rates observed in this trial wereslightly higher than those of the prospective randomized TARGIT-A and ELIOT Trials. This may be explained by22% of our patients being considered unsuitable for IORT by ASTRO Criteria. The low complication rates previouslyreported by our group as well as the low recurrence rates reported in this study support the cautious use andcontinued study of X-ray IORT in women with low-risk breast cancer.