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 ≤ 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 care 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 ≤ 2.0 cm and micrometastasis in the SLN.