Ο ρόλος του ογκογονιδίου HER2 σύγχρονη αντιμετώπιση του καρκίνου του στομάχου

Abstract

Aim: Anti-HER2 therapy was recently applied to advanced gastric cancer with HER2 overexpression and/or amplification tested by immunohistochemistry (ICH) and fluorescent in situ hybridization (FISH). However, FISH is technically demanding and expensive. Chromogenic in situ hybridization (CISH) uses a chromogenic substrate similar to IHC. The slides are visible under light microscopy and show correlation with morphology. Our aim was to assess HER2 status by IHC and CISH in gastric cancer.Methods: 120 gastric carcinomas combined on a multiple-punch tissue microarray, including lymph node metastases in 45 patients, were examined for HER2 overexpression and gene amplification by IHC and CISH.Results: Twenty-four (20%) of 120 tumours expressed HER2 by IHC. An IHC score of ≥2+ was observed in 20 tumours (16.6%). HER2 amplification was detected by CISH in 19 tumours (15.8%) and their matched lymph node metastases . Amplification was associated with intestinal phenotype (p<0.05), but did not show association with grading, staging or survival.Conclusion: In gastric cancer HER2 amplification is the only mechanism for HER2 protein overexpression and is preserved in lymph node metastases. The evaluation of the expression of HER2 protein in patients with gastric adenocarcinoma should be done by immunohistochemistry (ICH) and be verified by in situ hybridization. Chromogenic in situ hybridization (CISH) can be used as an alternative for FISH in HER2 testing. Our data do not support the prognostic role of HER2 status in gastric cancer and, as a result, do not advocate the addition of molecular treatment in the form of trastuzumab in gastric cancer patients.