However, there were some limitations in the study: (1) all of the studies came from China and did not include the patients of other countries; (2) the number of patients enrolled in some studies was relatively small, and not all cancer types of digestive system were under investigation; (3) there was no consensus on the cut-off estimates for differentiating high or low H19 expression; (4) no cohort studies met the inclusion criteria and were included. This evidence concerns the gene H19 and cancer.