Immunohistochemical detection of Her-2/neu overexpression in breast carcinoma in Nigerians: A 5-year retrospective study

Abstract

To determine the pattern of Her-2/neu status among breast carcinoma in the University of Benin Teaching Hospital, Benin City, Nigeria. Immunohistochemical staining for Her-2/neu was performed on 10% formalin-fixed, paraffin-embedded primary carcinoma of the breast from 83 patients, between 2003 and 2007 using anti-Her-2/neu rabbit polyclonal antibody (DakoCytomation, CA, USA) and reactivity detected by an avidin-biotin immunoperoxidase method. The clinicopathologic parameters analyzed were patients' age, histological types, and tumor grade. The Her-2/neu Dako scoring system was used. During the 5-year period, 83 histologically confirmed cases of invasive breast carcinoma were assessed for Her-2/neu status. These included 67 (80.7%) cases of invasive ductal carcinoma, nine cases of invasive lobular carcinoma (10.8%), three cases of medullary carcinoma (3.6%), two cases of papillary carcinoma (2.4%), and a case each of mucinous and clear cell carcinoma (1.2%). Mean age of patients was 48.9 ± 13.6 years with an age range of 25 to 83 years. Only nine (10.8%) cases showed immunopositivity for Her-2/neu. Seven of these were cases of invasive ductal carcinoma, while two were invasive lobular carcinoma. Tumors were predominantly high grade with grade III, II, and I accounting for 42, 28, and 13 cases, respectively. There was no significant correlation between patient age, the various histological types, tumor grade, and Her-2/neu positivity. This study indicates that Her-2/neu may not be useful in defining the prognosis of breast cancer in this environment. Nevertheless, it highlights the need for routine immunostaining for Her-2/neu before institution of trastuzumab (Herceptin) therapy.