Prognostic significance of cytokeratin-positive breast cancer metastases.

The most important discriminant in staging carcinoma of the breast is the presence of positive axillary lymph nodes. In this study, we determined if 45 female breast cancer patients originally classified as lymph node-negative by standard light microscopy (SLM) could be more accurately classified by immunohistochemical (IH) examination of their lymph nodes with an anticytokeratin monoclonal antibody cocktail. Identical sections of lymph nodes were sequentially examined by SLM and IH. Eight nodes (1%) in a total of five patients (11%) were positive by SLM. In comparison, 12 nodes (1.5%) in a total of nine patients (20%) were positive by IH. Five nodes were positive by IH and negative by SLM. There was no correlation between IH-detected metastases and tumor size or patient age. The survival curve for patients with IH-detected metastases was significantly worse than that of patients without IH-detected metastases. IH detection methods may be an important adjunct in staging breast cancer patients.