Abstract :
Background: Gastric cancer (GC) and gastro-oesophageal junction cancer (GEJC) are major causes of morbidity and mortality worldwide. Human epidermal growth factor receptor 2 (HER2)-positivity is a significant negative prognostic factor for GC and a wide range of HER2-positivity rates (6-35%) have been reported. The international ToGA trial (trastuzumab with chemotherapy in HER2-positive advanced GC) is the first large phase III trial to provide prospective information on the incidence of HER2 positivity in advanced GC.
Objective: To assess the percentage of HER2 positivity in gastric carcinoma by immunohistochemistry(IHC) for protein overexpression and the correlation with histological findings.
Methods: Formalin-fixed, paraffin-embedded tumor samples were collected from GC patients in Phramongkutklao hospital. The HER2 status of GC samples was determined using previously validated HER2-detection methods: immunohistochemistry (IHC) by primary immunoreagent 4B5 (PATHWAY_HER-2 rabbit
monoclonal antibody) using the Ventana automated slide staining IHC system. Samples identified as IHC 3+ were defined as HER2 positive. We analyzed these HER2 positivity findings in relation to the status of tumor and to the
histological subtype.
Result: Tumors from 68 patients were centrally tested for HER2 status: 18 of 68 cases (26.5%) were HER2. Tumor types (Lauren’s classification) are 36 cases of intestinal type, 22 cases of diffuse type, and 10 cases of mixed type. Tumor grades are 8, 24, and 36 cases of well, moderate, and poorly differentiated tumors respectively. Age, sex and pathological subtype are not significant affected HER2 status in both univariate and multivariate analysis. Only tumor grading has shown correlation with HER2 overexpression.
Conclusion: The prevalence of HER2-positive in gastric cancer from this study was similar to other studies in Western countries and had highest percentage of intestinal sub-type in HER2-positive. Interestingly, we found that high prevalence of well-differentiated in HER2-positive which has been postulated that there are other unknown factors which related clinical outcome beside HER2 over-expression.
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file/Thai-Journal-of-gastroenterology-vol-13-no-3-1186487.pdf