Women's College Research Institute

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Drinking and breast cancer risk

Fall 2011

Dr. Narod

In November, Dr. Steven Narod, senior scientist and head of the Familial Breast Cancer Research Unit at Women's College Research Institute and professor in the University of Toronto's Dalla Lana School of Public Health, published an editorial in the Journal of the American Medical Association (JAMA).

Narod's editorial, commenting on a Harvard study that linked moderate drinking to an increased risk of breast cancer, prompted 37 interviews for news stories appearing across North America.

The study he remarked on followed 105,986 women between 1980 and 2008, and found that women who had two or more alcoholic drinks per day had a 51 per cent increased risk of breast cancer. The researchers speculated that alcohol's tendency to increase circulating estrogen levels - which is known to be related to breast cancer - could be responsible for the increased risk.

In his accompanying editorial, Narod wrote that, although the report "provides more detail about the risks associated with different patterns of consumption," there is still "no data to provide assurance that giving up alcohol will reduce breast cancer risk."

But even though he says there's no evidence to support that quitting drinking later in life will lower risk, in his editorial, Narod does agree that the Harvard scientists' estrogen theory could be right. In fact he agreed that women who begin drinking at a young age could indeed be at a higher risk, because of a greater cumulative exposure to alcohol (and estrogen). Conversely, he says that women who decrease their consumption could theoretically lower their risk – though it's possible that the damage might already be done from decades of drinking.

Reporters used Narod's editorial to provide an alternate view suggesting that quitting drinking won't help lower breast cancer risk. But, especially when considered in the light of "drunkorexia," both the Harvard study and Narod's editorial still leave plenty of room for the possibility that young women who drink heavily may substantially increase their risk of developing breast cancer later on.

Read JAMA editorial

Narod SA. Alcohol and risk of breast cancer. JAMA, 306: 1920-1, 2011.

Back to Impact Fall 2011

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