Moderate drinking 'ups cancer risk'
Women who consume just three small alcoholic drinks a week face an increased risk of breast cancer, US researchers have warned.
Boston-based scientists found a 15 per cent increase in risk for those who drank an average of five to 9.9 grams of alcohol a day (or three to six small drinks per week).
And women who consumed at least 30 grams of alcohol daily (or at least two drinks a day) were 51 per cent more likely to develop breast cancer than those who never drank, according to the study published in the Journal of the American Medical Association.
While alcohol has long been known to be a risk factor for breast cancer, previously its effect at low levels had been less clear.
The team, led by Dr Wendy Chen from Brigham and Women's Hospital, analysed data on 105,986 participants in the Nurses's Health Study - of whom more than 7,600 were diagnosed with invasive breast cancer over a period of 18 years.
The report's authors said it was important to consider lifetime exposure when evaluating the effect of alcohol.
They wrote: "However, an individual will need to weigh the modest risks of light to moderate alcohol use on breast cancer development against the beneficial effects on cardiovascular disease to make the best personal choice regarding alcohol consumption."
Drinking small amounts of alcohol can reduce the risk of heart disease but only in men over 40 and women who have been through the menopause. And drinking more than these very low levels increases the risk of heart disease, as well as cancer.
The reason why alcohol raises breast cancer risk is unclear but may involve its effect on circulating oestrogen levels, they suggested.
Sarah Williams, health information officer at Cancer Research UK, said: "This study adds to already strong evidence that drinking even small amounts of alcohol increases the risk of breast cancer. Researchers found a small increased risk for low alcohol intake but the risk increases the more people drink. And the study re-confirmed that all types of alcohol - beer, wine and spirits - increase the risk of cancer.
Cutting down on alcohol can reduce the chance of developing breast cancer - as can keeping a healthy weight and being physically active. A healthy lifestyle isn't a guarantee against cancer but it helps stack the odds in our favour."
Copyright Press Association 2011