Abstract

Gastric cancer (GC) is the fifth most common type of cancer and the third leading cause of cancer-related deaths in the world. GC is a heterogeneous disease with diverse molecular and histological subtypes, which, may have different therapeutic implications. Using sophisticated molecular technologies and analyses, 3 separate groups recently provided genetic and epigenetic molecular classifications of GC: Singapore-Duke, The Cancer Genome Atlas project (TCGA) and the Asian Cancer Research Group (ACRG). These molecular classifications are time-consuming, complex, and costly and require sophisticated molecular technologies, which, prevent their widespread availability and use in clinical practice. Therefore, several practical pathological classifications were developed using immunohistochemical stains, fluorescent in situ hybridization and/or polymerase chain reaction (PCR), which, approximate, albeit not perfectly, the molecular classifications of GC. These are simple algorithms, less expensive and easy to reproduce in any pathology laboratory. Both molecular and histological classifications should be used for choosing adequate therapy and stratification purposes in clinical trials. This is a review of current molecular and pathological classification of GC.