CYP2E1 and breast cancer: Other possible mechanisms may include the following: the induction of cytochrome P450 2E1 by chronic drinking and associated oxidative stress, particularly for liver cancer; the solvent role of alcohol for tobacco carcinogens for upper digestive and respiratory tract cancers; alcohol‐induced alterations of serum levels of hormones and related signalling pathways for breast cancer; alcohol‐related liver cirrhosis for liver cancer; and alcohol‐induced changes in folate metabolism particularly for colorectal cancer.5