Drinking just one alcoholic drink a day significantly increases the risk of breast cancer, according to a new report from the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF).
The report also showed that vigorous exercise such as running or cycling reduces the risk of both pre- and post-menopausal breast cancer and that moderate exercise decreases the risk of post-menopausal breast cancer, which is the most common form of the disease.
The expansive report, which is the first such review to be carried out since 2010, evaluated 119 studies and included data on 12 million women across the globe and 260,000 cases of breast cancer.
It was found that drinking just one small glass of wine, beer or other alcoholic drink (about 10 grams of alcohol) per day increases pre-menopausal breast cancer risk by 5% and post-menopausal breast cancer risk by 9%.
This suggests there is no level of alcohol use that is completely safe in terms of breast cancer… If a woman is drinking, it would be better if she kept it to a lower amount."
Anne McTiernan (Fred Hutchinson Cancer Research Center, Seattle)
When analysing the effects of vigorous exercise, the researchers found that compared to the least active women, the most active women had a 17% of developing breast cancer if they were pre-menopausal and a 10% lower risk if they were post-menopausal. For moderate activity such as walking, the most active women were at a 13% lower risk compared with the least active women.
McTiernan says the evidence from this comprehensive and up-to-date report is clear. Keeping active, maintaining a healthy weight and limiting alcohol are all steps women can take to lower their risk of breast cancer.
The researchers acknowledge that many factors that women cannot control such as age and family history also influence breast cancer risk. However, all women can still take steps to lower the risk.
Alice Bender, Head of Nutrition Programs at AICR says: "Wherever you are with physical activity, try to nudge it up a bit, either a little longer or a little harder… There are no guarantees when it comes to cancer, but it's empowering to know you can do something to lower your risk."