Abstract P1-09-07: Omission of Axillary Surgery for Ipsilateral Breast Tumor Recurrence with Negative Nodes after Previous Breast-Conserving Surgery: Is It Oncologically Safe?

Background: Salvage mastectomy is traditionally recommended for patients who developed ipsilateral breast tumor recurrence (IBTR) in light of the previous breast irradiation. However, it remains controversial whether surgical axillary staging (SAS) is necessary for IBTR patients with negative nodes. This study aimed to evaluate the oncologic safety of omitting SAS for IBTR. Methods: We retrospectively identified patients who developed invasive IBTR with negative nodes after undergoing breast-conserving surgery (BCS). Patterns of care in nodal staging were analyzed based on prior axillary staging status. Clinicopathologic characteristics and adjuvant treatment of the initial tumor, as well as the IBTR, were compared between SAS and no SAS groups. Kaplan-Meier method and Cox regression model were utilized to compare the loco-regional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS), and overall survival (OS) rates after IBTR removal between the two groups. Results: A total of 154 IBTR patients were eligible for final analysis. Compared to no SAS group, SAS group was less likely to undergo ALND (15.1% vs 73.3%, p < 0.001) at initial BCS, had a longer recurrence interval (2.8 vs 2.1 years, p=0.03), and were more likely to have discordant molecular subtype with primary tumor (35.8% vs 12.9%, p=0.001). However, the extent of axillary staging did not affect systemic or radiation recommendations. In the subgroup of patients without previous ALND, the clinicopathologic characteristics were roughly comparable. Pathologic analysis revealed pathologically uninvolved nodal status in approximately 85% of patients receiving SAS at time of IBTR in the overall population and the subgroup (Table 1). No significant differences were observed in LRRFS, DMFS and OS between the two groups (Table 2). Conclusion: For node-negative IBTR patients, we observed selection bias on the basis of prior ALND, shorter recurrence interval, and concordant molecular subtype favoring no SAS, but comparable LRRFS, DMFS, and OS. These results support wider consideration of sparing SAS in the management of IBTR, especially in patients without previous ALND. Table 1. Pathologic axillary staging in patients receiving axillary surgery at time of IBTR. Table 2. Cox regression analysis of LRRFS, DMFS, and OS after IBTR. Citation Format: Feilin Qu, Caijin Lin, Jun-Jie Li, Zhi-Ming Shao. Omission of Axillary Surgery for Ipsilateral Breast Tumor Recurrence with Negative Nodes after Previous Breast-Conserving Surgery: Is It Oncologically Safe? [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-09-07.