Intraoperative boost radiotherapy with 50 kV X-rays versus external radiotherapy in breast cancer: Single-center experiences

Abstract

Background: Intraoperative radiotherapy (IORT) within breast conserving surgery (BCS) is progressively utilized to deliver the optimal dose of radiotherapy immediately after the excision of cancer during the same operation to the well-vascularized tissue and to the margin of resected cancer to damage the cancer cells, which might remain nearby the tumor just on time without no delay as radical irradiation for particular cases or as boost dose for others. Methods: This study reports 54-month single-center experiences after introduction to deliver IORT (50 kV x-ray) as a tumor bed boost in BCS for breast cancer and comparison with external beam radiation therapy (EBRT). In this retrospective study, 255 patients (stages 1-3) with breast cancer were treated with BCS and IORT in the Cancer Research Center, Shahid Beheshti University of Medical Sciences (April 2014-September 2018). They received 20 Gy IORT as a boost compared with 321 patients in the same stages with EBRT. Results: Within 54 months, there were 3 (1.2%) occurrences of local recurrence in IORT patients compared with 8 (2.5%) local recurrences in EBRT patients (P = 0.361) and 12 (4.7%) metastasis in the IORT group vs. 20 (6.2%) in the EBRT group (P = 0.724). The 5-year disease-free survival (DFS) was 85.1% in the IORT group compared with 86% in the EBRT group. Conclusions: IORT tumor bed boost with 50 kV x-ray during breast conserving therapy had a better outcome, but it was not significant compared with EBRT.