PTEN and gastric cancer: As a critical tumor suppressor, mutation or deficiency of PTEN gene contributes to tumorigenesis in the digestive system, including esophageal carcinoma (Eng, 2003), gastric cancer (GC) (Wadhwa et al., 2013), colorectal carcinoma (CRC) (Ling et al., 2015), hepatocellular carcinoma (HCC) (Horie et al., 2004), pancreatic cancer (Ni et al., 2017), gall bladder cancer (Roa et al., 2015), and cholangiocarcinoma (Lee et al., 2012).