Alcohol and breast cancer

The relationship between alcohol and Breast Cancer has been a subject of much research. It has long been considered a risk factor for breast cancer in women. The International Agency for Research on Cancer has declared that there is sufficient scientific evidence to classify alcoholic beverages a Group 1 carcinogen that causes breast cancer in women. Group 1 carcinogens are the substances with the clearest scientific evidence that they cause cancer, such as smoking tobacco.

A woman drinking an average of two units of alcohol per day has 8% higher risk of developing breast cancer than a woman who drinks an average of one unit of alcohol per day. A study of more than 1,280,000 middle-aged British women concluded that for every additional drink regularly consumed per day, the incidence of breast cancer increases by 1.1%. Approximately 6% (between 3.2% and 8.8%) of breast cancers reported in the UK each year could be prevented if drinking was reduced to a very low level (i.e. less than 1 unit/week).

Among women, breast cancer comprises 60% of alcohol-attributable cancers.

A study of 17,647 nurses found that high drinking levels more than doubled risk of breast cancer with 2% increase risk for each additional drink per week consumed. Binge drinking of 4–5 drinks increases the risk by 55%.

The mechanisms of increased breast cancer risk by alcohol may be:

Their magnitude likely depends on the amount of alcohol consumed.

Susceptibility to the breast cancer risk of alcohol may also be increased by other dietary factors, (e.g. folate deficiency), lifestyle habits (including use of hormone replacement therapy), or biological characteristics (e.g. as hormone receptor expression in tumor cells).

Studies suggest that drinking alcohol during pregnancy may affect the likelihood of breast cancer in daughters. "For women who are pregnant, ingestion of alcohol, even in moderation, may lead to elevated circulating oestradiol levels, either through a reduction of melatonin or some other mechanism. This may then affect the developing mammary tissue such that the lifetime risk of breast cancer is raised in their daughters."

Moderate alcohol consumption has also been found to increase the breast cancer risk.

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Wikipedia