Sentinel lymph node biopsy with metastasis: can axillary dissection be avoided in some patients with breast cancer?

PURPOSE Recent studies have suggested that the sentinel lymph node (SLN) biopsy is an accurate alternative staging procedure for women with breast cancer. The goal of this study was to identify a subset of breast cancer patients in whom metastatic disease was confined only to the SLN. MATERIALS AND METHODS From two institutions, we recruited 222 women with breast cancer for SLN biopsy. A SLN biopsy was performed in each patient, followed by an axillary dissection in 182 patients. Histologic and immunohistochemical cytokeratin stains were used on all SLNs. RESULTS The SLN was identified in 220 (97. 8%) of the 225 biopsies. Evidence of metastatic breast cancer in the SLN was found in 60 (27.0%) of the 222 patients. Of these patients, 32 (53.3%) had evidence of tumor in the SLN only. By multivariate analysis, two factors were found to be significantly associated with a higher likelihood of tumor involvement in the non-SLNs: primary tumor size larger than 2.0 cm (P =.0004) and macrometastasis (> 2.0 mm) in the SLN (P =.002). Additional analysis revealed that none (0%; 95% confidence interval, 0% to 18.5%) of the 18 patients with primary tumors < or = 2.0 cm and micrometastasis to the SLN had remaining axillary lymph node involvement. CONCLUSION The primary tumor size and metastasis size in the SLN are independent factors in predicting the incidence of tumor in the non-SLNs. Therefore, the SLN biopsy alone may be adequate for staging and/or therapy decision making in patients with primary breast tumors < or = 2.0 cm and micrometastasis in the SLN.