Background: The axillary recurrence (AR) rate after negative sentinel node biopsy (SNB) in patients with high risk of axillary metastases is largely unknown. The aim of this study was to analyze the risk factors for isolated AR after negative SNB with special interest in large or multifocal tumors.
Methods: A prospective SNB registry was analyzed for 2,408 invasive breast cancer patients operated between 2001 and 2007. No axillary clearance was performed in 1,309 cases with a negative SNB, including 1,138 small unifocal tumors, 121 small multifocal tumors, 48 large unifocal tumors, and 2 large multifocal tumors.
Results: Six (0.5%) isolated AR were observed during a median follow-up of 43 months. Four (0.4%) patients with small unifocal tumors and two (1.6%) with small multifocal tumors had isolated AR (p = 0.179). None of the patients with large unifocal or multifocal tumors had isolated AR. Instead of tumor size and multifocality, estrogen receptor negativity (p < 0.001), nuclear grade III (p < 0.001), Her-2 status (p = 0.002), no radiotherapy (p = 0.005), and mastectomy (p = 0.005) were found to be associated with AR.
Conclusions: A remarkable proportion of patients with large unifocal tumors and small multifocal tumors may avoid unnecessary AC due to tumor negative SNB, without an excessive risk of AR.