Utility of cytologic specimens in the evaluation of prognostic and predictive factors of breast cancer: current issues and future directions.

Although numerous biological and molecular markers of breast cancer have been identified over the past two decades, traditional factors such as estrogen receptor (ER), progesterone receptor (PR), and HER-2 remain among the most useful indicators of prognosis and therapeutic response to treatment. These markers can be reliably evaluated in cytologic specimens, particularly in fine-needle aspirates (FNA) of primary or metastatic breast cancer. Accurate assessment of ER, PR, and HER-2 is critical in the treatment of breast cancer patients. A review of the literature, however, shows considerable interlaboratory variability in the detection of these markers and reporting of the test results. Because therapies are now being directed toward individual molecular targets, there is a need for increased standardization of such analyses. Current practices should follow consensus recommendations set by the College of American Pathologists and the American Society for Clinical Oncology, and the results should be monitored through quality-assurance programs. The utility of cytologic specimens of breast lesions is also not limited to evaluation of individual prognostic and predictive factors. Cytologic specimens have been used successfully for genomic and proteomic studies. Such investigational studies are under way and offer great potential for revolutionizing the prediction of patient outcomes and disease response to therapy, as well as assessment of risk of developing breast cancer. Copyright 2004 Wiley-Liss, Inc.