Abstract

Purpose Adjuvant whole-breast irradiation with a boost to the tumor bed is the standard of treatment after breast-conserving surgery. Boost dose can be delivered either intraoperatively or externally. The purpose of this study is to review the literature regarding intraoperative radiation therapy (IORT) after neoadjuvant chemotherapy (NACT) in patients with locally advanced breast cancer (LABC). Methods The present study is a review of English-language articles regarding IORT after NACT in patients with LABC published between 1998 and 2020. For this, the databases of PubMed, Medline, Web of Science, EBSCO, IEEE, Scopus, and Springer were searched. The results of the studies were combined using the random-effects model in the meta-analysis. Results In patients with LABC who have received NACT, our review demonstrated encouraging results for boost IORT in terms of toxicity (0 in Spaich et al.'s single-arm study) and local control (96 in Homaei Shandiz et al.'s single-arm study). In comparison to the external beam irradiation boost (EBIB), IORT was noninferior in local control (98.5 vs 88.1, p-value 0.2 in Fastner et al.'s study) and superior in overall survival (HR = 0.19, p = 0.016 in Kolberg et al.'s study). Conclusions IORT (electron or photon) after NACT in patients with LABC is a safe procedure with comparable efficacy to EBIB. Highly accurate dose prescription, evasion of the proliferative cytokine cascade, and elimination of the effects of geometric and temporal miss all lead to this conclusion that boost IORT may be superior to EBIB.