Women who take even one alcoholic drink a day are raising their risk of developing breast cancer by 5%, according to a study published today in the journal Alcohol and Alcoholism.
The journal has published a new review of research that looks at the relationship of alcohol consumption and breast cancer.
Alcohol drinking overall accounts for about 5% of breast cancers in Northern Europe and North America and as much as 10% in countries such as Italy and France, where drinking alcohol is common among women.
Breast cancer is the most common form of the disease in Europe and the USA amongst women and several population studies have also shown that women have a high prevalence of light drinking. It has been known for some time that alcohol consumption is a risk factor for cancer developing in various organs of the body.
For this new review study, a team of researchers from Germany and Italy set out to analyse epidemiological data on the relationship of alcohol and breast cancer, with a particular focus on light alcohol consumption.
When analysing the effects of light alcohol drinking, the authors reviewed research published before November 2011, focusing on 113 papers reporting breast cancer risk estimates for light drinkers. The analysis of studies from across the world included 44,552 cases in the category of non-drinkers and 77,539 cases in the light drinking category.
They found that there was a modest but significant association between light drinking – one drink a day – and breast cancer and a proven 5% increase in risk. The review also showed that each increased alcohol consumption increased the risk of breast cancer. Heavy alcohol consumption – defined as three or more drinks a day – was found to have a 40-50% increased risk of breast cancer.
As alcohol consumption might affect the risk of cancer through hormone related mechanisms, the review particularly looked at the association between alcohol consumption and the risk of breast cancer through hormone-related mechanisms such as estrogen receptor (ER) and progesterone receptor (PR) status.
The researchers found that there was significant research to suggest that alcohol consumption increased the risk of all ER+ tumours by 27% and placed a 14% risk for all ER- breast cancers for the highest versus lowest level of alcohol drinking.
Subsequent investigations by the team found further support for a stronger association between heavy alcohol consumption and ER + breast cancers.
The report’s authors conclude: “Since there is no threshold level of ethanol for breast cancer risk, the breast is one of the most sensitive organs for the carcinogenic action of alcohol.
“Healthy women should not exceed one drink/day (equivalent to 10–12g of ethanol). Women at an elevated risk for breast cancer such as those with a positive family history, benign mastopathy or other conditions associated with an increased breast cancer risk should avoid alcohol or consume alcohol only occasionally.”