The risk of axillary relapse after sentinel lymph node biopsy for breast cancer is comparable with that of axillary lymph node dissection: a follow-up study of 4008 procedures.

Objective: We sought to identify the rate of axillary recurrence after sentinel lymph node (SLN) biopsy for breast cancer.
Summary Background Data: SLN biopsy is a new standard of care for axillary lymph node staging in breast cancer. Nevertheless, most validated series of SLN biopsy confirm that the SLN is falsely negative in 5-10% of node-positive cases, and few studies report the rate of axillary local recurrence (LR) for that subset of patients staged by SLN biopsy alone.
Methods: Through December of 2002, 4008 consecutive SLN biopsy procedures were performed at Memorial Sloan-Kettering Cancer Center for unilateral invasive breast cancer. Patients were categorized in 4 groups: SLN-negative with axillary lymph node dissection (ALND; n = 326), SLN-negative without ALND (n = 2340), SLN-positive with ALND (n = 1132), and SLN-positive without ALND (n = 210). Clinical and pathologic characteristics and follow-up data for each of the 4 cohorts were evaluated with emphasis on patterns of axillary LR.
Results: With a median follow-up of 31 months (range, 1-75), axillary LR occurred in 10/4008 (0.25%) patients overall. In 3 cases (0.07%) the axillary LR was the first site of treatment failure, in 4 (0.1%) it was coincident with breast LR, and in 3 (0.07%) it was coincident with distant metastases. Axillary LR was more frequent among the unconventionally treated SLN-positive/no ALND patients than in the other 3 conventionally treated cohorts (1.4% versus 0.18%, P = 0.013).
Conclusions: Axillary LR after SLN biopsy, with or without ALND, is a rare event, and this low relapse rate supports wider use of SLN biopsy for breast cancer staging. There is a low-risk subset of SLN-positive patients in whom completion ALND may not be required.