One or two drinks a day increase the risk of cancer in women

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The researchers found that each daily alcoholic drink significantly increased the risk of cancers of the breast, liver and rectum. And, in women who also smoked, it increased the risk of cancers of the mouth and throat.

The researchers found that, among the drinkers, women drank on average about one alcoholic drink per day, which is typical for women in many developed countries, such as the UK and the US. In these countries where women drink low to moderate amounts of alcohol, about 118 of these cancers are diagnosed for every 1000 women up to the age of 75.

The researchers calculated that for every additional drink regularly consumed each day there would be about 15 extra cases of these cancers diagnosed for every 1000 women up to the age of 75 in developed countries. So among 1000 woman averaging one drink per day 15 extra cancers would develop by age 75, and among 1000 women averaging two drinks per day 30 extra cancers would develop by age 75 and so on.

Overall, about 13 per cent of cancers of the breast, liver, rectum and mouth and throat are due to alcohol consumption.

Most of these extra cases are breast cancer; the researchers estimated that about 5,000 cases of breast cancer in the UK (11 per cent of the 45,000 cases diagnosed each year) can be attributed to women’s consumption of alcohol.

Cancer Research UK scientists at the University of Oxford's cancer epidemiology unit analysed data from more than a million middle-aged women from the Million Women Study.

Dr Naomi Allen, lead study author, said: "These findings suggest that even relatively low levels of drinking – about one or two alcoholic drinks every day – increase a woman’s risk of developing cancer of the breast, liver and rectum, and in smokers, cancers of the mouth and throat."

The researchers found that the increased cancer risk did not depend on what kind of alcohol was drunk – only the amount. For instance, women who drank wine exclusively had a similar risk of developing cancer as those who drank other alcoholic beverages or a mixture of drinks.

Among the women studied, fewer than two per cent regularly drank more than three drinks per day. The study included 68,775 cases of cancer, registered over 7.2 years of follow-up.

Sara Hiom, director of health information at Cancer Research UK, said: "We know that too much alcohol increases the risk of a number of cancers. This latest study shows that even relatively low levels of drinking increase a woman’s risk. It is important that women are as well informed as possible so they can take responsible decisions over how much alcohol they drink.

"Cancer Research UK recommends that the more you cut down on alcohol, the more you reduce your cancer risk. The more you drink the greater the risk."

Reference

1. Allen NE, Beral V, et al. Moderate alcohol intake and cancer incidence in women. Journal of the National Cancer Institute 2009; 101(5): 296–305. doi: 10.1093/jnci/djn514

klíčová slova: alcohol, breast cancer, liver cancer, rectal cancer