Prevalence of human epidermal growth factor receptor-2(her-2) over-expression in patients with gastric and gastro-esophageal junction carcinoma seen at Kenyatta national hospital

Abstract

Background; Gastric cancer in Kenya is ranked third in both males and females. Most patients present clinically with advanced unresectable disease have poor prognosis despite administration of standard chemotherapy. Human epidermal growth factor receptor – 2(HER-2) over expression in gastric cancer is related to poor outcome. Advances in molecular therapy have identified HER-2 to be an important component in the treatment of advanced gastric cancer. The prevalence of HER2 in Kenya is unknown. Objective: To determine the prevalence of HER-2 over expression in patients with gastric and gastro-oesophageal junction carcinoma at Kenyatta National Hospital. Methodology; Descriptive Cross sectional study on patients with histological diagnosis from endoscopic/resection specimens of gastric or GEJ cancer at KNH. A sample of 66 patients was selected by progressive sampling. Approval was obtained from the KNH/UON ethics and research committee. Data was collected using a pretested questionnaire. All tissue blocks were tested for HER-2 receptor protein using IHC. Data entry and analysis was done via SPSS version 21.0. Results; Study sample of 66 patients were included in the study with a mean age of 60.7 years and males consisting of 66.7%. 42 specimens were obtained from OGD and 24 from surgically resected specimens. Approximately 91% of the tumours were located in the gastric region. Gastric adenocarcinoma accounted for89.4 %( N=59) mainly intestinal (78.8%, N=52) and diffuse (9.1%, N=6) while 1.5% (N=1) was a denosquamous. HER-2 over-expression was diagnosed in 42.4% (N=28) of patients. HER-2 over-expression was not significantly associated with age (P= 0.844) and gender (P= 0.682). The anatomical site was not significantly associated with HER-2 over expression (P=1). HER-2 over-expression was found mostly in adenocarcinoma (96.4%) compared to 3.6% in adenosquamous, with intestinal type showing highest rate of over-expression (87.5%) compared to diffuse (12.5%). Conclusion: HER-2 over-expression was found to be higher in our study (42.4%) compared to most of the studies. HER-2 over-expression is observed predominantly in intestinal type of gastric and GEJ adenocarcinomas.