Drinking just one glass of wine or other alcoholic drink a day can increase breast cancer risk, reveals a major new report that analysed data on 12 million women.
But vigorous exercise such as running or fast bicycling can help decreases the risk of both pre- and post-menopausal breast cancers, said the report by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF).
"With this comprehensive and up-to-date report the evidence is clear: Having a physically active lifestyle, maintaining a healthy weight throughout life and limiting alcohol -- these are all steps women can take to lower their risk," said Anne McTiernan, lead author of the report and a cancer prevention expert at the Fred Hutchinson Cancer Research Centre in Seattle, Washington.
Researchers systematically collated and evaluated the scientific research worldwide on how diet, weight and exercise affect breast cancer risk in the first such review since 2010.
The report analysed 119 studies, including data on 12 million women and 260,000 cases of breast cancer.
The report found strong evidence that drinking the equivalent of a small glass of wine or beer a day (about 10 grams alcohol content) increases pre-menopausal breast cancer risk by five per cent and post-menopausal breast cancer risk by nine per cent.
For vigorous exercise, pre-menopausal women who were the most active had a 17 per cent lower risk and post-menopausal women had a 10 per cent lower risk of developing breast cancer compared to those who were the least active.
While there are many factors that women cannot control, the good news from this report is that all women can take steps to lower their breast cancer risk, said Alice Bender from American Institute for Cancer Research.
"Wherever you are with physical activity, try to nudge it up a bit, either a little longer or a little harder. Make simple food shifts to boost protection -- substitute veggies like carrots, bell peppers or green salad for chips and crackers and if you drink alcohol, stick to a single drink or less," Bender said.
According to the US National Cancer Institute at the National Institutes of Health, alcohol may increase the risk of cancer in multiple ways including increasing blood levels of estrogen, a sex hormone linked to the risk of breast cancer.