Mismatch repair protein expression in gastric carcinoma patients

Gastric cancer is one of the most aggressive malignancies. Although there has been a slight increase in overall survival due to the inclusion of targeted medications in the standard chemotherapeutic treatment paradigm, the prognosis remains poor. New evidence suggests that certain molecular and histopathologic tumor characteristics, as well as staging, may also influence patients’ prognosis. Indeed, two detailed genomic classifications of gastric cancer have recently been developed by The Cancer Genome Atlas (TCGA) and the Asian Cancer Research Group (ACRG), showing that microsatellite instability (MSI) is a distinct subgroup related to gastric cancer patients’ prognosis. Interestingly, the MSI-H subgroup was identified as a separate entity of GC in both of these classifications that are relevant to the prognosis of gastric cancer. Microsatellite instability (MSI) is caused most frequently by deficiency in the mismatch repair proterin (MMR) (including MLH1, MSH2, PMS2, MSH6) and can be defined by immunohistochemistry (IHC). Microsatellite instability offers a good prognostic marker associated with different cancer types. Therefore, the identification of MMR in gastric cancer is very important to provide valuable prognostic information and personalized treatment Key words: gastric cancer, microsatellite instability, mismatch protein repair deficiency, immunohistochemistry, prognosis.