Study of HER2 expression and its relation to tumor characteristics among gastric adenocarcinoma patients of Firoozgar hospital, Tehran, Iran; in 2010 and 2011

One million people are diagnosed with gastric cancer (GC) annually and the prognosis for patients with advanced GC or gastroesophageal junction (GEJ) cancer is usually poor with a median survival time of 8 to 10 months. Recent reports have identified that anti HER2 target therapy improved the median survival rate in patients with HER2 positive GC; but a wide range of HER2 overexpression incidence has been reported in different studies. This study was conducted to determine the incidence of HER2 overexpression and its relationship to tumor characteristics. All gastric or GEJ adenocarcinoma patients who underwent a curative surgical resection in Firoozgar Hospital, Tehran, Iran between 2010 and 2011 were entered into this cross-sectional study. The formalin-fixed and paraffin wax-embedded tissue blocks used in the present study were surgical resection specimens obtained from 115 patients. All tumor samples were examined for HER2 expression by an immunohistochemistry (IHC) assay and HER2 IHC score 3+ was considered positive. The study sample consisted of 115 subjects, 81 males and 34 females with a mean age of 61.01 years (30-85 years, SD=11.605). HER2 overexpression was detected in 13 (11.3%) of the patients. HER2 overexpression was significantly higher in tumors ≥5cm compared to those <5cm (P=0.01). But, there was no significant relationship between tumor histological subtype, GC stage or tumor location and HER2 overexpression (P=0.607, 0.745, 0.491). The findings of the present study indicated that the incidence of HER2 overexpression in gastric adenocarcinoma was 11.3%. The higher incidence of HER2 overexpression in patients with tumors ≥5cm maybe indicate that anti HER2 target therapy administration for these patients could be more beneficial.