Association between Her2/neu expression and hormon receptor status in breast cancer patients.

Abstract

Determination of HER2/neu expression by immunohistochemistry is mandatory for application of Herceptin® therapy in breast cancer patients. The purpose of this study was to investigate the association between HER2/neu expression and hormone receptor status, as well as with other clinicopathological parameters in breast cancer patients. HER2/neu, p53 and Ki-67 expression was determined in 169 postoperative stage I-III (UICC, 1997) breast cancer patients using the standardized DAKO HercepsTest® and immunoperoxidase technique, respectively. The results of HER2/neu immunoreactivity were evaluated by performing the standardized scoring system (0 = negative, 1+ = weakly positive, 2+ = positive, 3+ = strongly positive staining), while ER and PgR were scored in a semiquantitative fashion (ER-ICA and PR-ICA). The results from HER2/neu expression were correlated to hormonal receptor status and clinicopathological parameters (tumor size, histopathologic grade, nuclear grade, histologic type of the tumor, lymph node status and patient age). Statistical significance was determined with χ2 and Fisher’s exact test. HER2/neu expression was positive in 66 patients (37%). There was no significant association between the values of HER2/neu and ER/PgR status, or with any other clinicopathological parameter. ER status significantly correlated with PgR status (p<0.01), tumor size (p<0.01), lymph-node involvement (p<0.01) and tumor type (p<0.01). PgR status was related to the histopathologic grade (p<0.01), lymph-node status (p<0.01), tumor type (p<0.01) and patient age (p<0.01). HER2/neu is a relatively new promising marker in predicting the response to target specific therapy. However, its predictive value remains a complex and inconclusive subject. According to our results, the prognostic potential of HER2/neu seems to be independent from hormone receptor status and any other clinicopathological parameter in breast cancer patients.