Purpose: To determine risks of stomach and colorectal cancers due to waterpipe smoking, cooking methods in an interaction with CYP1A1 and GSTM1 and Helicobacter pylori infection by a Molecular Epidemiological Case-control study in the North Viet Nam. Study Population: Our hospital-based case-control study on stomach and colorectal cancer from 2003 to 2011 has recruited successfully for 725 incident cases of stomach, 195 incident cases of colon, 227 incident cases of rectal cancers. Controls of 1,186 cases were selected from the patients who were hospitalized for surgery in these hospitals during the same period, matching on .a sex and age +/- 5. Expected findings: The present study will determine for the association between waterpipe smoking, cooking methods and the risk of stomach and colorectal cancers. The results will increase our understanding and controlling tobacco smoking and dietary risks of these cancer sites.