Preoperative partial breast radiation for favorable early-stage breast cancer: a narrative review

Background and Objective: Adjuvant partial breast irradiation (PBI) is a well-established treatment for appropriately selected women with early-stage breast cancer. Preoperative PBI is a newer approach with some advantages compared to post-operative PBI, including potential for decreased toxicity, tumor response assessment, treatment stratification, and prognostication. Here, we summarize emerging data from prospective studies demonstrating safety and efficacy of preoperative PBI and explore techniques for assessing tumor response. We further review ongoing studies and discuss the intriguing possibility of utilizing this technique to adopt a non-operative approach for select patients with early-stage breast cancer. Methods: We conducted a comprehensive literature search utilizing PubMed and ClinicalTrials.gov prior to August 01, 2024 to identify prospective studies in English documenting outcomes for women treated with a neoadjuvant partial breast approach. We utilized keywords of "partial breast radiation", "breast cancer radiation", "breast cancer radiotherapy", "partial breast radiotherapy for breast cancer". Key Content and Findings: A growing number of prospective studies demonstrate that preoperative PBI may be a safe and effective alternative to postoperative PBI for appropriately selected patients with earlystage breast cancer. A subset of women treated with preoperative PBI achieve a pathologic complete response (pCR) following treatment. However, careful preoperative evaluation is critical to select patients suitable for a partial breast approach to avoid overtreatment. Conclusions: Preoperative PBI is a promising alternative to traditional postoperative radiotherapy for appropriately selected women with early-stage breast cancer. Further prospective studies are necessary to further refine understanding of the optimal selection criteria and clinical outcomes for patients treated with this approach.