C-MET positivity and its relationship with histopathological findings in gastric carcinomas exhibiting HER2 gene expression.

Abstract

Co-expressions of receptor tyrosine kinases such as c-MET and HER2 were reported in many studies. The concomitant expression is associated with more aggressive clinical course. In this study, it was intended to investigate the correlation of the positivity of c-MET and HER2 with histopathologic findings and their impacts on prognosis. After the decision of the ethics committee, a total of 64 cases, whose HER 2 status was studied by dual silver in situ hybridization/immunohistochemistry method, were included in the study. Immunohistochemical staining for c-MET was performed to all cases and the evaluation was performed similarly to the criteria for HER2 evaluation, but cytoplasmic staining was also considered significant. The data were analyzed using SPSS 20 for Windows. c-MET positivity which is considered by the score of 2+ and 3+ was found only in 34.4% of HER2 positive cases while it was 59.3% in HER2 negative cases (P = 0.045). The sole histopathological feature associated with c-MET positivity was distal gastric localization (P = 0.016). Even though higher rates of c-MET positivity in HER2 positive cases were stated in the literature, contrary results were obtained in this study. Comparing the HER2+/c-MET + co-expression group with the other groups, no difference was found about age, sex, macroscopic and microscopic characteristics. The presence of c-MET positivity in cases with HER2 expression suggests that c-MET expression might be associated with the resistance to Trastuzumab.