Abstract ES5-3: Surgical considerations after preoperative therapy for hormone receptor positive breast cancer

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Abstract Session Title: Multidisciplinary approaches to optimize surgical therapy in hormone receptor positive breast cancer Talk Title: Surgical considerations after preoperative therapy in hormone receptor positive breast cancer Abstract: Preoperative therapy increases rates of breast conservation and decreases the need for axillary lymph node dissection (ALND) in select patients. In hormone receptor positive (HR+) HER2 negative breast cancer patients the choice between neoadjuvant chemotherapy (NAC) and neoadjuvant endocrine therapy (NET) to achieve breast conservation can be challenging and the low rates of axillary pCR with either approach have been associated with higher rates of ALND. For HR+ HER2- patients receiving NAC, available literature supports performing sentinel lymph node biopsy (SLNB) after receipt of therapy with the decision to perform axillary lymph node dissection dictated by the status of the sentinel lymph nodes. For patients receiving NET, there is little data to guide surgical management of the axilla. In a recent review of the NCDB, we assessed axillary management by initial treatment strategy (NET, NAC, or upfront surgery) among a large population of Stage II-III HR+ HER2- breast cancer patients and found that SLNB use after NET in both clinically node negative and clinically node positive patients was similar to SLNB use with upfront surgery. However, among those with pN1 disease, patients who received NET were less likely to undergo ALND. While failure to achieve a nodal pCR after NAC is associated with inferior DFS and OS outcomes; whether or not the same is true after NET remains uncertain. Further, the impact of residual nodal disease after NET on LRR remains an area of ongoing investigation. Understanding the differences in and implications of residual nodal disease after neoadjuvant therapy (NAC vs NET) in HR+ HER2- breast cancer provides the opportunity to develop subtype specific strategies for optimal surgical management of the axilla. Citation Format: TA King. Surgical considerations after preoperative therapy for hormone receptor positive breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr ES5-3.