The primary objective is to investigate the protective effect of long-term low dose use of aspirin on colorectal, esophageal and gastric cancer in adult subjects from Taiwan.~Secondary objectives are to evaluate the protective effect by duration of low-dose aspirin use on colorectal cancer, the effect of discontinuation of aspirin on colorectal cancer prevention, the staging distribution of colorectal cancer and the description of fatal cases due to colorectal cancer.~Aspirin use will be identified through Taiwanese National Health Insurance (NIH) data from 2000 to 2015. Cancer cases and staging of the three cancer types will be ascertained through the Taiwan Cancer Registry, using data from 2000 to 2014. Fatal cases will be ascertained using Mortality database from 2000 to 2015.
The study evaluates the protective effect of low-dose aspirin use on gastrointestinal cancers (colorectal, esophageal and gastric cancers) in long-term users, episodic users and non-users of aspirin in Taiwan.