HER2 Expression in Gastric Adenocarcinoma—a Study in a Tertiary Care Centre in South India

Abstract

According to the literature available, HER2(human epidermal growth factor 2)status in gastric carcinoma has been studied worldwide, however there is a paucity of published data from India. Hence, this study was taken up to evaluate HER2 overexpression in gastric adenocarcinoma patients and to assess the relationship between its expression and clinicopathological tumor parameters. Prospective study was conducted in a teaching hospital over a period of 27 months. Total or subtotal gastrectomy resection specimens and small biopsies were included in the study. Immunohistochemistry (IHC) was carried out on all the cases to evaluate the expression of HER2 in formalin-fixed paraffin-embedded tissue samples. Fluorescence Insitu Hybridization (FISH) was done for equivocal cases on IHC. The data was analyzed using Chi square test / Fisher's Exact Test. Odds ratio was computed between HER2 and other pathologic variables. HER2 overexpression was confirmed in 16 (27.6 %) cases of which 15 (93.8 %) cases were of intestinal type whereas only 1 (6.2 %) case of diffuse type adenocarcinoma. Hence, HER2 positivity was significantly more common in the intestinal type of gastric cancer compared to the diffuse type (p = 0.045). Positivity of HER2 was more in small biopsies as compared to the resection specimens in this study but the p value was not significant. There was no difference in HER2 overexpression in relation to the age, gender, tumor site, tumor differentiation and stage. HER2 overexpression is more prevalent in the intestinal subtype. The relatively high percentage of HER2 positive tumors may provide a useful target for immunotherapy of these cancers.

Human epidermal growth factor receptor 2 overexpression in gastric and gastroesophageal junction adenocarcinoma in patients seen at the University Teaching Hospital, Lusaka, Zambia

“…Information linking gastric tumour differentiation and HER2 overexpression have shown variable results with some studies showing an association, 24,25,26 while others have not. 20,27 The anti-HER2 antibody trastuzumab, when added to chemotherapy, improves the survival of patients with HER2 positive GGEAC. 6 Trastuzumab is available in Zambia and patients with HER2 positive breast cancers receive this treatment.…”

“…Information linking gastric tumour differentiation and HER2 overexpression have shown variable results with some studies showing an association, 24 , 25 , 26 while others have not. 20 , 27 …”

Study of HER-2/neu status in adenocarcinoma of stomach and gastroesophageal junction

“…Only 3+ score on IHC were considered positive in studies conducted by Halder et al, Gupta et al, Rajagopal et al and Ghosh et al [18][19][20][21] In another study conducted by Tewari et al^5, both 2+ and 3+ scores on IHC were considered positive resulting in a HER-2 positive rate of 21.4%. Among the Indian studies, FISH was performed on equivocal (IHC 2+) cases only in limited studies-Patil et al, Sunitha et al, Aditi et al and Sekaran et al [14][15][16][17] The overall HER-2 positivity described by various studies in English literature ranged between 7% and 44.2%. 14,17 The variation in prevalence rates in several studies could be attributed to the varying protocols followed for designating HER-2/neu status and the antibody used in IHC technique.…”

Frequency of HER2/neu Overexpression in Gastrointestinal AdenocarcinomasAn Immunohistochemical Study in A Tertiary Care Hospital

“…As per the studies available a wide range of HER2/ neu expression was observed in gastrointestinal adenocarcinomas. [6,7,8,9,10,11,12,13,14] In ToGA trial HER2 over expression of 3+ positivity was seen in 10.4% for resected samples. [2] For colorectal adenocarcinomas 3+ positivity on IHC was seen in 0.5 % cases.…”

“…3+ and 2+ positive cases have to be subjected to fluroscence in situ hybridization (FISH) or chromogenic insitu hybridization (CISH) for confirmation. [5,9] There is increased demand for HER2neu testing on gastrointestinal adenocarcinomas because of the survival benefit due to available targeted therapy. As many monoclonal antibodies directed against HER2 were available this can be done routinely in all gastrointestinal adenocarcinomas, not only for the targeted therapy but also as a prognostic tool.…”