Thursday, October 21, 2010

Wine and breast cancer: an update

With October being the annual exercise in breast cancer awareness, our attention turns to the ongoing issue of drinking and breast cancer risk. What we usually hear is the established advice that alcohol consumption in any form contributes to the risk of developing breast cancer, in a direct ratio of about one daily drink to a 10% increase. But if you have been following my posts here, you will know that the question of wine consumption and breast cancer is considerably more nuanced, and it remains entirely possible-even likely, in my analysis-that red wine decreases risk, in the right amounts. A recent study from the Fred Hutchinson Cancer Research Center here in Seattle, in collaboration with major cancer centers around the country, helps to shed some light on the subject.

But first we need to revisit the question of why alcohol could contribute to cancer in the first place. As I point out in my book, a scientifically provable basis for alcohol leading to the cellular changes that progress to cancer remains elusive. The best idea out there is that it somehow interacts with estrogen receptors, which would imply that only certain types of breast cancer (know as estrogen-receptor positive) would correlate with drinking. However, no large studies had previously looked at drinking and breast cancer subtypes before the recent Hutch project. What they found was a relationship of ER positive cancer only in an uncommon variant called lobular carcinoma, but not the much more common ductal type. This particular study did not evaluate subcategories of drinking, however, but it nevertheless raises more questions than it answers. Here’s why:

If alcohol contributes to breast cancer via the only plausible mechanism proposed, by interacting with estrogen receptors, the risk would not correlate only to an uncommon subtype that also happened to be ER positive. So we still lack a plausible cause-effect explanation for the role of alcohol in breast cancer. One reason why these studies give such conflicting results is the reliance on self-reporting, which is wildly unreliable when it comes to the question of drinking habits. Another is that drinking habits tend to be erratic; few have only wine, only a glass or two a day, and always with dinner. Studies from populations that do have more traditional wine drinking patterns show a reduction in breast cancer risk. As these populations become more and more modernized, the opportunity to get meaningful data from population studies diminishes. So pink may be the theme color for breast cancer awareness, but I prefer to call it rosé.

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