Immunohistochemical Profile of Human Epidermal Growth Factor Receptor 2 in Gastric Cancer in Rwanda

Background: Of the cancers diagnosed in Rwanda, stomach cancer is one of the most encountered. In fact, Rwanda belongs to the region where it is most incident in Africa. Most of the patients present with advanced disease. Studies showed that some gastric cancers overexpress Human Epidermal Growth Factor Receptor 2 (HER2/neu) protein and can be treated with Herceptin/Tras-tuzumab. This targeted therapy improves survival in patients with advanced disease. We conducted a study on Immunohistochemical profile of HER2/neu in gastric adenocarcinomas at two main Rwandan tertiary centers. Methodology: We tested for HER2/NEU in gastric adenocarcinomas diagnosed at University Teaching Hospital of Kigali (CHUK) and University Teaching Hospital of Butare (CHUB). Demographic and pathologic parameters were collected. Immunohistochemistry (IHC) for HER2/neu using c-erb/HER-2/neu (clone SP3) Rabbit Monoclonal antibody was done. Using the guidelines established by Hoffman et al., the agreed score between 2 Rwandan pathologists and 1 USA pathologist was considered each time. Data were entered and statistically analyzed using SPSS 22. Descriptive statistical analysis method was used. P-value calculated with Chi-square analysis for positive vs negative and equivocal negative to correlate HER2/neu overexpression with other variables across both hospitals. Results: A total of 286 cases were tested. HER2/neu overexpression (score 3+ or positive) was found in 29 cases (10.1%). 8 cases (2.8%) were equivocal negative (score 2+) while 249 cases (87.1%) were negative (score 0 and 1+). Conclusion: HER2/neu is overexpressed in a subset of gastric cancers in Rwanda, a phenomenon that has been reported in other areas of the world. Testing for HER2/neu could identify patients who would get a targeted treatment with Herceptin.

Keywords: Gastric, Cancer, Rwanda, HER2, Immunohistochemistry