In patients with breast cancer, micrometastases and submicrometastases are increasingly found in sentinel nodes when step sectioning and/or immunohistochemical staining are applied. The aims of the current study were to investigate the incidence of micro- and submicrometastases in the sentinel node, to estimate the risk of additional metastases in the remaining axillary lymph nodes, and to consider implications for staging and treatment.
A total of 2150 breast cancer patients who had undergone axillary sentinel node biopsy between 1999 and 2004 were retrospectively evaluated.
In all, 649 patients (30%) had a tumor-positive axillary sentinel node. Of these 649 patients, 148 had (23%) micrometastases and 105 (16%) submicrometastases. Of the 148 patients with micrometastases, 106 underwent axillary lymph node dissection (ALND) and additional metastases were found in 20 patients (19%). Sixteen (15%) had macrometastases and were upstaged. The other 4 patients had additional micrometastases. Seven of the 106 patients (7%) received additional systemic treatment based on the findings in the axillary lymph nodes. Fifty-four of the 105 patients with submicrometastases underwent ALND. Two (4%) of them had additional macrometastases and were upstaged and 2 had additional micrometastases. None received additional treatment based on the ALND findings.
Of the involved sentinel nodes, 23% contained micrometastases and 16% submicrometastases. Additional macrometastases were found in 15% and 4%, respectively, and treatment was altered in 7%. Based on these findings, offering additional treatment of the axilla is suggested in patients with micrometastases, but refraining from ALND in patients with submicrometastases in their sentinel node. Cancer 2006. © 2006 American Cancer Society.