A retrospective evaluation of I-SPY2 clinical trial data indicates that in appropriately selected patients with breast cancer, sentinel lymph node surgery with adjuvant radiation may provide appropriate oncologic control without the routine use of axillary dissection. Judy C. Boughey, MD, of the Mayo Clinic, Rochester, Minnesota, and colleagues presented their results during the 2024 Society of Surgical Oncology (SSO) Annual Meeting (Abstract 3). Although follow-up in the I-SPY2 cohort thus far is fairly short (median, 3.5 years), they found that compared with selective use of sentinel lymph node surgery alone after neoadjuvant chemotherapy, axillary dissection did not improve axillary recurrence, locoregional recurrence, distant recurrence, or event-free survival—even in patients with node-positive disease.

They evaluated the outcomes of patients—those who did and did not have residual nodal disease—who underwent axillary surgery after neoadjuvant chemotherapy between 2011 and 2022. Axillary surgery was classified as sentinel lymph node surgery alone or as axillary dissection (with or without sentinel lymph node surgery).

Slightly more than 1,500 patients were included: 714 (47.1%) had clinically node-negative disease at diagnosis, of whom 104 (14.6%) had pathologically node-positive disease; 801 (52.9%) had clinically node-positive disease at diagnosis, of whom 396 (49.4%) had pathologically node-positive disease. Sentinel lymph node surgery alone was performed in 805 of 1,015 (79.3%) patients with pathologically node-negative disease and in 126 of 500 patients (25.2%) with pathologically node-positive disease.

Dr. Boughey and co-investigators found that among patients who had pathologically node-negative disease, no significant differences occurred between those who underwent sentinel lymph node surgery alone and those who had axillary dissection in the 5-year estimated rate of axillary recurrence, locoregional recurrence, distant recurrence, and event-free survival. Among patients who had pathologically node-positive disease, there was no difference between sentinel lymph node surgery alone and axillary dissection in the 5-year estimated axillary recurrence or locoregional recurrence.