Study confirms breast cancer link to low alcohol use

A newly published study from the University of Victoria's Centre for Addictions Research of BC (CARBC) confirms that moderate drinkers have an increased risk of breast cancer. The study shows that consuming an average of up to two drinks a day is associated with an 8.5 per cent increase in the risk, compared to abstaining from alcohol.

According to the Canadian Breast Cancer Foundation approximately 5,000 Canadian women die from breast cancer each year. According to international studies, 5 to 10 per cent of breast cancer deaths are attributable to alcohol. This means that every year, 250 to 500 Canadian women die of breast cancer due to their alcohol consumption.

Previous research investigating the relationship between low-dose alcohol use and breast cancer has sometimes produced conflicting results. Some studies found no increased risk for low-dose or "moderate" drinking. This new study, co-authored by CARBC director Tim Stockwell, former associate researcher with CARBC Cornelia Zeisser, and Tanya Chikritzhs of the National Drug Research Institute at Curtin University in Australia published in Alcoholism: Clinical and Experimental Research, analyzed 60 studies done before 2013.

Of those 60, only six were free of potentially serious biases: many because former drinkers were misclassified as abstainers, while other studies misclassified occasional drinkers as abstainers. This last bias in particular resulted in an underestimation of the risk of disease, the CARBC study shows.

When corrected for these biases, the findings confirmed a significantly increased risk for breast cancer from low-dose consumption—levels currently within Canada's Low-Risk Drinking Guidelines for women.

Stockwell says "these results should encourage caution with alcohol consumption. Drinking within Canada's low-risk drinking guidelines is associated with a very small increase in risk of breast cancer as well as of some other cancers. In general, less drinking means less risk to health."