Clinical Efficacy and Side Effects of IORT as Tumor Bed Boost During Breast-Conserving Surgery in Breast Cancer Patients Following Neoadjuvant Chemotherapy

Abstract

The efficacy of intraoperative radiotherapy (IORT) as boost dose following neoadjuvant chemotherapy (NACT) is not clearly established yet. This trial evaluated the outcome and complications of IORT boost dose after NACT in patients with breast cancer. This study was a single-arm phase II clinical trial conducted at tertiary referral centers including Omid and Imam Reza Educational Hospitals and Pasteur Private Hospital, Mashhad, Iran. Twenty-four women with breast cancer underwent breast-preservation surgery following the neoadjuvant chemotherapy were enrolled. During BCS, a 20 Gy dose was prescribed to the tumor bed using intrabeam system Zeiss followed by 50 Gy/2 Gy whole breast radiotherapy. Patients were followed for complications of treatment and disease recurrence at 2 years. Toxicity criteria of the RTOG revealed there was only one case of acute toxicity grade 4 as necrosis. During the follow up, two cases of grade III fibrosis were observed. With a median follow up of 29.5 months, one patient died due to cancer with the median survival time of 23.93 months and the 2-year survival rate of 95.5 ± 4.4%. Moreover, one localized relapses in the breast, one recurrent in axillary region and distant metastases, and two distant metastases were diagnosed. The mean free survival was 23.23 months, and the 2-year free survival rate was 87.1%. The results of this study showed that in the short-term follow up, IORT results in terms of local control, side effects and cosmetic outcome after neoadjuvant chemotherapy in breast cancer patients are acceptable.