A Drink a Day Raises Women's Risk of Cancer, Study Indicates(2)
Based on the findings, the researchers estimated that about 5 percent of all cancers diagnosed in women each year in the United States are the result of low to moderate alcohol consumption. Most are breast cancers, with drinking accounting for 11 percent of cases -- about 20,000 extra cases each year -- the researchers estimated.
In any group of 1,000 U.S. women up to age 75 who consumed an average of one drink a day, the researchers calculated, there would be 15 extra cancers; two drinks per day would result in 30 extra cancers, and so forth.
The risk appeared the same regardless of whether women drank wine, beer or any other type of alcohol. Allen noted that even less than one drink per day may increase the risk.
"There doesn't seem to be a threshold at which alcohol consumption is safe," she said.
The reason alcohol increases the risk for cancer is not entirely clear, but there are several possibilities, including that it enables carcinogens to do their damage, increases inflammation or, in the case of breast cancer, boosts estrogen levels.
Several researchers noted that the findings were essentially consistent with previous studies, and despite its size the study does have shortcomings. The researchers could not, for example, distinguish between women who drank only one or two drinks every day and those who drank seven drinks all at once. Some researchers worried the findings would unnecessarily frighten women and deprive them of the possible health benefits of an occasional drink.
"We can't use this to scare people away from alcohol," said Eric Rimm of the Harvard School of Public Health.
Allen plans to analyze the study data to try to determine whether the net risks from cancer outweigh any heart benefits. But others researchers were doubtful.
"Among women, the major cause of death by far during the middle age years is cancer," Michael S. Lauer and Paul Sorlie of the National Heart, Lung and Blood Institute noted in a editorial accompanying the study. "For this large group, the only reasonable recommendation we can make is there is no clear evidence that alcohol has medical benefits."
As it turns out, the federal government is rewriting its dietary guidelines, including the part about alcohol consumption, and will consider the new study in that process.
"No one study is ever sufficient to make a recommendation," said Linda Van Horn, a professor of preventive medicine at Northwestern University who is chairing the committee revising the guidelines. "But it will be added to the body of literature that will be reviewed."
In the meantime, several experts said women should consult with their doctors about whether they should drink.
"It really comes down to a personal decision based on their own history and risk factors," Rimm said. "But it shouldn't be based only on health. Some people drink for cultural reasons; some people drink for religious reasons. I personally think it enhances the flavor of meals, and some people think it enhances the company you're with."
