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Location: Marriott Marquis
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PQA 05 - PQA 05: Breast Cancer and Nonmalignant Disease Poster Q&A

2741 - Radiation or Axillary Lymph Node Dissection after Positive Sentinel Lymph Node Biopsy Following Neoadjuvant Chemotherapy for Breast Cancer: A Retrospective Review

Monday, September 30, 2024
3:00 PM – 4:00 PM ET
Location: Hall C

Screen: 3

    Presenter(s)

  • Kathleen Waeldner, BA

    Robert Larner, MD College of Medicine at the University of Vermont
    Burlington, VT

K. Waeldner1, C. Chin2, and P. Gilbo2; 1Larner College of Medicine at the University of Vermont, Burlington, VT, 2Department of Radiation Oncology, Nuvance Health, Norwalk, CT

Purpose/Objective(s): Management of the axilla continues to move through a paradigm shift for breast cancer patients. It has been established that radiation therapy (RT) can be utilized in lieu of an axillary lymph node dissection (ALND) for positive nodes after sentinel lymph node biopsy (SLNB). In the neoadjuvant setting, it has similarly been established that SLNB and/or targeted axillary dissection (TAD) is safe and effective for staging the axilla after neoadjuvant chemotherapy (NAC) for clinically node negative patients (ycN0). In the setting where a positive node is identified (ypN+), management has defaulted to ALND, and whether we can apply the equivalency of RT in this setting is an active trial question (A011202). However, there is a significant subset of patients that are unable to or otherwise choose not to undergo an ALND in this setting due to the morbidity of the procedure. There is limited direct evidence to support the omission of ALND. Materials/

Methods: We sought to examine the rate of regional recurrence of ycN0 patients (by surgeon’s clinical exam and/or post-NAC imaging) who were subsequently identified to have ypN+ disease as identified on SLNB or TAD from 2013 – 2023. Patients were divided into two groups: Group 1) ALND 10+ nodes and Group 2) SLNB/ALND <10 nodes. We secondarily examined the overall survival (OS), local-regional control (LRC), control of distant metastatic spread (DM) and the impact of axillary management on outcomes using a log-rank method. Patients that received neoadjuvant endocrine therapy were excluded.
Results: 58 patients were identified to have ypN+ disease followed neoadjuvant therapy. Of those, 35 were identified to have NAC with ycN0 on their surgeon’s examination and were available for analysis. With a median follow-up of 38 months, the 3-year rates of LRC, OS, and DM was 97% (81.4 - 99.6), 96% (69.8 – 97.8), and 90% (64.4- 94.3). Dividing patients by axillary evaluation, group 1 contained 14 patients (40%) and group 2 contained 21 patients (60%). There was no statistical difference between the rate of regional recurrence between groups 1 and 2 (p=0.22). There were no regional recurrences in Group 2. There was also no difference in OS or DM (p=0.59, p=0.92). All patients received nodal-directed RT .
Conclusion: For patients with ycN0, ypN+ disease there is no difference in disease outcomes between patients managed with ALND or nodal-directed RT in this small retrospective series. RT remains a reasonable option for patients who decline or cannot receive an ALND. Ongoing trials will define if this approach will serve as a new standard of care.