Clinical Outcomes of Breast-Conserving Surgery with Synchronous 50-kV X-ray Intraoperative Partial Breast Irradiation in Patients Aged 64 Years or Older with Low-Risk Breast Cancer.

BACKGROUND: Breast-conserving surgery with synchronous 50-kV X-ray intraoperative radiation therapy (TARGIT-IORT) is a convenient form of partial breast irradiation; however, the existing literature supports a wide range of local control rates.

OBJECTIVES: We investigated the treatment effectiveness and toxic effects of TARGIT-IORT in a patient cohort aged 64 years or older with low-risk breast cancer.

DESIGN: Retrospective analysis.

METHODS: Patients who received breast-conserving surgery with synchronous TARGIT-IORT at a single institution from 2016 to 2019 were reviewed. Additional whole breast irradiation was recommended at the discretion of the treating radiation oncologist. Baseline patient demographics and treatment details were recorded. Acute and chronic toxicities, measured using the Common Terminology Criteria for Adverse Events version 3.0 or 4.0 and breast cosmetic outcomes, using the Harvard Cosmesis score, were recorded. Locoregional recurrence, distant metastasis, and overall survival were recorded, and 5-year rates were estimated using the Kaplan-Meier method.

RESULTS: 61 patients were included with a median follow-up of 3.5 years and median age of 72 years. Eight (13%) patients received additional whole breast irradiation, and fifty-four (89%) received adjuvant hormone therapy. There were no local, regional, or distance recurrences. One patient died of complications from COVID-19 infection. Grade 2 + acute and chronic toxicities were observed in 6 (12%) and 7 (14%) patients, respectively. One patient experienced a grade 3 acute toxicity. Cosmetic outcome was "excellent" or "good" in 45 (92%) patients.

CONCLUSIONS: Breast TARGIT-IORT was well tolerated and conferred excellent disease control in this cohort of patients with low-risk breast cancer. While continued follow-up is required, TARGIT-IORT may be an appropriate treatment option for this population.