Though the exact details of how alcohol increases cancer risk are unknown, the American Cancer Society notes there are several different ways that alcohol may contribute to a person's elevated risk of developing cancer.
* Tissue damage: Alcohol can be an irritant in the mouth and throat as well as other areas of the body, forcing damaged cells to repair themselves. That forcing of the hand may lead to DNA changes in the cells, and such changes may act as a steppingstone to cancer. Alcohol also can cause inflammation and scarring in the liver, and as liver cells attempt to repair that damage, mistakes in the DNA may result, increasing a person's risk for cancer. In the colon and rectum, bacteria can convert alcohol into acetaldehyde, a chemical which studies have shown causes cancer in lab animals.
* Body weight: Excessive consumption of alcohol often causes people to gain weight, and being overweight or obese is a major risk factor for various types of cancer.
* Hormones: Women who consume alcohol may be prone to elevated levels of estrogen, a hormone associated with hormone-receptor-positive breast cancer that plays a significant role in the growth and development of breast tissue. According to Breastcancer.org, when compared to women who abstain from alcohol, women who have three alcoholic drinks per week have a 15 percent higher risk of developing breast cancer, and that may be a byproduct of the effect alcohol has on a woman's hormone levels.
* Effect on harmful chemicals: Alcohol can dissolve other harmful chemicals, including those found in tobacco smoke, making it easier for them to enter the cells lining the upper digestive tract. The ACS theorizes that this may play a role in why the combination of smoking and drinking is far more likely to cause cancers in the mouth or throat than either smoking or drinking alone.
* Effect on nutrients: The body's cells need a vitamin called folate to stay healthy. But alcohol consumption can compromise the body's ability to absorb folate from foods, which is especially problematic for heavy drinkers who do not get enough nutrients in their daily diets. Low folate levels have been linked to breast and colorectal cancers.