Perspectives of the stomach cancer treatment: the introduction of molecular targeted therapy and the hope for cure

The overall survival of patients with gastric cancer has increased markedly in Korea, even higher than those of developed nations in Western world. It is due to the virtue of Korean National Cancer Screening Program and nowadays more than half of patients are diagnosed at the early stage of gastric cancer. However, for patients with unresectable gastric cancer, the outcomes of traditional cytotoxic chemotherapy regimens stay at a median survival of 9-11 months. The knowledge of cancer biology and the data from gene expression profiling has explosively expanded. Alternations in the expression of receptor tyrosine kinases pathways including Human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), phosphatydyl inositol 3 kinase/mammalian target of rapamycin (PI3K/mTOR), hepatocyte growth factor receptor (HGFR/MET), and fibroblast growth factor receptor (FGFR) were proved to be critical in cancer cell survival and biological agents targeting those altered receptor tyrosine kinases, their ligands and downstream effector molecules are developed for anti-cancer purpose. Until now, only trastuzumab succeeded to significantly increase overall survival of patients with HER2 overexpressing gastric cancer. Other agents including bevacizumab, gefitinib, erlotinib, and lapatinib failed to achieve the efficacy in survival gain over standard chemotherapy. Insights about the variations between regions, races, and individuals call for the effort to find reliable predictive biomarkers for drug efficacy and to design finely stratified clinical trials. Compared to current treatment paradigms, it is hoped that molecularly targeted treatment along with conventional cytotoxic chemotherapy will lead to significant gains in survival.