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

Context: 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.

Aims: 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.

Subjects And Methods: 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.

Statistical Analysis Used: The data were analyzed using SPSS 20 for Windows.

Results: 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).

Conclusions: 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.