RESUMEN
OBJECTIVE: The purpose of this study is to determine the prevalence rate of estrogen and progesterone receptors and HER 2/neu in the breast cancer biopsies analyzed in the Laboratory of Immunohistochemistry of the University of Puerto Rico School of Medicine in the year 2000. This data may serve as a reference point for future studies of the epidemiological aspects of breast cancer among women living in Puerto Rico. BACKGROUND: Determination of estrogen receptor (ER) and progesterone receptor (PR) on biopsy specimens of breast carcinoma prior to treatment is standard practice in the management of breast carcinoma. ER and PR are used to identify patients who are likely to respond to endocrine therapy. The prevalence of ER, PR and Her2/neu among USA women is 77%, 55% and 10-34%, respectively. One of the major clinical roles for testing HER 2/neu expression is to determine eligibility for treatment with Trastuzumab. METHODS: Retrospective analysis of 309 breast cancer biopsies was done. Paraffin embedded blocks of breast cancer tissue biopsies were received from different hospitals and Pathology Laboratories located throughout the island specifically for routine analysis of steroid receptor (ER/PR) and/or HER 2/neu expression. Immunostaining was performed in a Ventana Medical Systems automated instrument. RESULTS: Positive nuclear staining for ER and PR were seen in 65.9% (203/308) and 51.8% (159/307), respectively. In the HER2/neu test, 27.8% (46/165) gave a strong and complete membranous staining (score 3+). CONCLUSIONS: There is a lower prevalence of estrogen receptor in the breast cancer biopsies of women living in Puerto Rico than their USA counterparts, but similar prevalence of progesterone receptor status and HER 2/neu protein over expression.