Prognostic Significance of HER-2 Expression in Gastric Cancer

Abstract

In gastric cancers we purposed to examine the relationship between age, gender, invasion depth, lymph node metastasis, lymphovascular invasion, Lauren's classification, presence of perineural invasion and the expression of Human Epidermal Growth Receptor (HER-2) by immunohistochemical (IHC) and dual-color silver-enhanced in situ hybridization (D-SISH) method. In our study, 242 gastric resection materials that were studied HER-2 by IHC and/or D-SISH method referred to our department between January 2014 and December 2017 for malignancy were included. The relationship between HER-2 expression rate and prognostic parameters was investigated. No statistical relation was found between age and gender and HER-2 positivity in either method. No statistically significant results were obtained between lymphovascular invasion, lymph node metastasis, presence of perineural invasion, depth of invasion and Lauren classification, and HER-2 positivity by immunohistochemical and D-SISH method. In our study, no statistically significant results were obtained between important prognostic parameters and HER-2 positivity with either IHC or D-SISH method. In 24.1% of the cases that were HER-2 positive by IHC, positivity was not observed with the D-SISH method. Also, 20.8% of the cases reported as immunohistochemically uncertain (equivocal) were seen as positive by the D-SISH method. Based on all these results, we would like to state that HER-2 positivity / negativity determined by IHC can be changed by the D-SISH method. In addition, although it was shown in our study that HER-2 has no prognostic significance in gastric carcinomas, it is reported in studies in the literature that the addition of Trastuzumab to chemotherapy increases survival. For this reason, we think that it would be more beneficial to apply the IHC and D SISH method together to obtain the true HER-2 result.