Alcohol raises risk of breast cancer

Drinking, but not smoking linked to breast cancer.
13 November 2002

TOM CLARKE

Heavy drinkers are 46% more likely to develop breast cancer. © GettyImages

Up to 4% of breast cancers in the developed world can be attributed to alcohol, according to a new analysis. Smoking, on the other hand, seems to have little effect on breast-cancer risk.

The beneficial effects of moderate drinking - on the heart and circulation - probably outweigh the increased risk of breast cancer, the study finds. But heavy drinkers are definitely in danger.

The analysis drew on data from 53 previous studies. The international Collaborative Group on Hormonal Factors in Breast Cancer compared 58,515 women with breast cancer and 95,067 without it.

Those averaging one glass of wine, small beer or measure of spirits a day are 7% more likely to develop breast cancer over their lifetime than teetotalers, the data suggests. Those sinking six drinks a day on average are 46% more likely to develop breast cancer. In other words, drinking probably accounts for 2,000 breast cancers diagnosed in Britain each year out of a total of 40,000.

There has never been much evidence of a strong link between smoking and breast cancer. The study compared non-drinkers who smoked with teatotallers who had never smoked and found little difference - confirming the suspicions of most epidemiologists.

The effects of alcohol consumption have been studied in detail before, but evidence remained equivocal and hotly debated. "This report is giving a definitive answer as to those effects," says study co-author Richard Doll of the University of Oxford, UK.

Definitive might not be the right word, says Klim McPherson, who studies alcohol and breast cancer at the University of Bristol, UK. Although the new study shows a definite correlation, the exact role of alcohol is far from clear. A connection "is plausible, but essentially not proven", he says.

People nearly always underestimate how much they drink, and this would have biased the study, he argues. Other factors could be confusing the interpretation, too. People who are stressed routinely drink more, for example, and stress is strongly implicated in cancer risk, says McPherson, although it is impossible to measure accurately.

Increasing age is the strongest risk factor for breast cancer: the older a woman is, the more likely she is to develop the disease. Overall, 1 in 8 women in the United States will develop breast cancer in their lives, compared with 1 in 9 in Britain.

1. Collaborative group on hormonal factors in breast cancer. Alcohol, tobacco and breast cancer - collaborative reanalysis of individual data from 53 epidemiological studies, including 58,515 women with breast cancer and 95,067 women without the disease. British Journal of Cancer, 87, 1234 - 1245, (2002). |Homepage|