Drinking Alcohol Linked to Higher Risk of Breast Cancer, Study Finds

In contrast to previous studies, both moderate and heavy drinking were associated with a rise in breast cancer, regardless of beverage preference

Jacob Gaffney
Posted: September 28, 2007

Researchers from the Kaiser Permanente Division of Research in Oakland, Calif., delivered words of caution to women wine drinkers. At the European Cancer Conference in Barcelona, Spain, held in late September, Kaiser Permanente lead scientist Arthur Klatsky told the conference that women who drank between one and two alcoholic drinks per day increased their risk of breast cancer by 10 percent, compared with light drinkers who drank less than one drink a day.

"This strongly confirms the relation of ethyl alcohol per se to increased risk," Klatsky said. Furthermore, the risk of breast cancer increased by 30 percent in women who drank more than three drinks a day, regardless of the woman's preference for wine, beer or spirits. This is a level similar to women who smoke a pack of cigarettes a day, Klatsky added. "To put it into context, it is not much different from the increased risk associated with women taking estrogenic hormones," which have been linked to a higher risk of breast cancer.

The researchers studied the drinking habits of 70,033 women from different ethnicities who supplied information during health examinations between 1978 and 1985. Nearly 3,000 of these women had been diagnosed with breast cancer by the end of the research period, in 2004. Klastky and his team compared the women's drinking habits—both how much and what type—to the rates of breast cancer in order to draw their conclusion.

However, the new findings by the Kaiser Permanente scientists contrast the results of other studies on the role of lifestyle decisions and their relation to the development of breast cancer. For instance, Dr. Curtis Ellison of Boston University concluded from another study that light drinking does not increase the risk of breast cancer.

"The potential importance of this new report is that women preferring wine did not have a lower risk than those preferring beer or spirits, which does not support many studies showing that the polyphenols in red wine may help protect against cancer," said Ellison, who has said he had only read Klatsky's abstract, and couldn't make any definitive statement until he read the study in full.

"We know that this dataset includes a high percentage of better-educated and affluent California women who drink only white wine, so there is a good chance of residual confounding"—meaning an unmeasurable factor—"or perhaps even over-adjustment for confounding," which could skew the results, explained Ellison. "And binge drinking, hormone-replacement therapy, and low folate intake [all] increase the breast-cancer risk from alcohol, so we need to see if any of these factors were adjusted for before making any conclusions about this study."

Laura Baglietto, senior researcher at the Cancer Council Victoria, Melbourne, Australia found that eating high amounts of folic acid, which is found in leafy greens, citrus fruits, beans and peas, may wipe out any risk of breast cancer attributable to moderate alcohol consumption. Folic acid is a B vitamin that helps produce red blood cells and create and maintain the DNA of new cells.

Klatsky did note that the responsible consumption of red wine can protect against heart attacks. "We think that the heart-protection benefit from red wine is real, but is probably derived mostly from alcohol-induced higher HDL [good] cholesterol, reduced blood clotting and reduced diabetes," he said. However, "none of these mechanisms are known to have anything to do with breast cancer," he added.

Klatsky also said that medical advice on lifestyle decisions needed to be made by qualified doctors working on a person-to-person basis. "The only general statement that could be made as a result of our findings is that it provides more evidence for why heavy drinkers should quit or cut down," Klatsky said.