CDH1 and CDH1-related diffuse gastric and lobular breast cancer syndrome: Abrogation of CDH1 expression by mutation, deletion or promoter hypermethylation is a feature of many epithelial tumours, including prostate, ovarian, lung and hepatocellular carcinomas, and is the hallmark of both the sporadic and familial forms of diffuse gastric cancer (DGC) and lobular breast cancer (LBC) [1, 6].