Detection of Micrometastases of Breast Cancer by Immunohistochemical Analysis of Cytokeratin.

PURPOSE Axillary lymph node metastases are the single most important predictor of overall survival in patients with breast cancer. Micrometastases are defined by the American Joint Committee on Cancer as tumor foci less than or equal to 2 mm in greatest dimension. Recently, up to 30% of breast cancer patients were reported to have micrometastases. In this paper, to assess the rate of micrometastases in patients with stage I breast cancer, we attempted to determine the most useful marker of the micrometastases in node negative cases by routine histopathologic examination of regional lymph nodes and comparison of the results with the influencing factors on prognosis. MATERIALS AND METHODS We performed immunohisto chemical staining for pancytokeratin, cytokeratin 7, cytokeratin 20 and CEA to identify which protein was the most useful marker for the detection of micrometastases in 86 node negative cases and determined the correlation between histological and clinical data. RESULTS A total of 5 lymph nodes in 5 separate cases showed micrometastases among the total 1,296 lymph nodes and 86 cases. The rates of micrometastases of lymph nodes and cases were 0.38% and 5.8%, respectively. The tumor type of micrometastasis was infiltrating ductal carcinoma in all cases. None of the microme tastases cases showed any relationship with tumor grade, tumor size, expression of ER and PR, patient survival rate or recurrence rate. The most useful marker to detect micrometastases was pancytokeratin. CONCLUSION The results of this study indicate that micrometastasis of axillary lymph nodes does not carry any independent prognostic significance.