ABSTRACT
BACKGROUND: Once the diagnosis of operable breast cancer has been made, the single most predictive factor is lymph node status. Although patients with lymph node initially reported as histologically negative have a relatively good prognosis, the relapse rate is still considerable. In an effort to detect micrometastases in the axillary nodes, various antibodies have been used that recognize membrane and cytokeratin antigens. Cytokeratin antigens are expressed by epithelial tumors and are not expressed by normal lymphoid tissues. This study uses an immunohistochemical method to examine the incidence and the prognostic significance of such micrometastases in a series of patients with "node-negative" breast cancer. METHODS: The study population consisted of a retrospective series of 150 patient who were treated at Soonchunhyang University Hospital for breast cancer between March 1992 and February 1998. Based on the original pathologic examination, patients had negative axillary nodes. Pan-cytokeratin, a cocktail of monoclonal antibodies to cytokeratin (58 kd, 56 kd, 52 kd, 45 kd), and the avidin-biotin-peroxidase- complex technique were used to detect micrometastases in paraffin embedded lymph nodes. RESULTS: Micrometastases were detected in 16 (10.7%) patients. The recurrence rate for patients with micrometastases was 6.3% (1/16), and the recurrence rate for patients without micrometastases was 1.5% (2/134). Micrometastases correlated with the histological type (P=0.026) and were seen more frequently with larger tumor size, higher anaplastic nuclear grade, and overexpression of p53.