Local recurrence in nipple-sparing mastectomy without intraoperative radiotherapy (IORT) in breast cancer

Background: Nipple-sparing mastectomy (NSM) is increasingly used in breast cancer treatment. Concerns remain about residual tissue beneath the nipple-areolar complex (NAC) and the risk of locoregional recurrence (LRR). This study aimed to evaluate recurrence in NSM patients with or without radiation therapy (RT) and to assess the role of RT. Methods: Retrospective review of patients with ductal carcinoma in situ (DCIS) or invasive breast cancer who underwent NSM with immediate reconstruction without intraoperative radiotherapy (IORT) from January 2007 to July 2021. LRR was the primary outcome; secondary outcomes included overall survival (OS), disease-free survival (DFS), and factors associated with outcomes and RT use. Results: A total of 148 NSMs were analyzed, including 116 invasive cancers and 33 DCIS cases. The mean age was 43 years, most patients were premenopausal (80%), T1 to T2 (94%), node-negative (64%), and estrogen receptor (ER) positive (82%). Positive margins occurred in 10 patients (7%). Chemotherapy was administered to 91 (68%), hormonal therapy to 118 (83%), and trastuzumab to half of 21 human epidermal growth factor receptor 2 (HER2) positive patients. Whole breast RT was given to 42 patients (28%). After a median follow-up of 72 months, 9 patients (6%) experienced LRR. RT did not significantly affect recurrence or survival. Ten-year OS was 100% vs. 94.7% (P=0.08) and DFS was 88.2% vs. 97.6% (P=0.24) for patients without and with RT, respectively. Conclusions: NSM without IORT is safe, and selective RT guided by tumor, nodal, and margin status achieves low LRR, even in higher-risk patients.