For women, the potential benefits from one alcoholic drink perhaps should be reconsidered.
As little as one drink a day increases a woman’s risk of several types of cancer by 13%, according to a British study of more than 1 million women. The risk is not statistically large, and scientists already knew that alcohol consumption was associated with an increased risk to women of these cancers, which include tumors of the breast, esophagus, larynx, rectum and liver.
“What is novel about this study is that even low to moderate amounts of alcohol increase the risk,” said epidemiologist Naomi E. Allen of the University of Oxford, who led the study published today in the Journal of the National Cancer Institute.
She estimated that about 5% of cancers in U.S. women, about 30,000 cases per year, are due to such low levels of consumption.
“From the standpoint of cancer risk, the message of this report could not be clearer. There is no level of alcohol consumption that can be considered safe” for women, wrote Dr. Michael S. Lauer and Paul Sorlie of the National Heart, Lung and Blood Institute in an editorial accompanying the study.
Previous studies have indicated that there is a cardiovascular benefit for both men and women from having a single drink every day, but the new findings in women suggest that the risk of cancer outweighs that potential benefit.
Allen, however, thinks it’s too soon to draw that conclusion. She is now conducting a study of potential cardiovascular benefits in the same group of women.
“Only then will we be in a position to comment on the overall benefit,” she said.
Allen and her colleagues studied 1,280,296 women between the ages of 45 and 75 who attended breast-cancer screening clinics between 1996 and 2001 -- one in every four U.K. women in their age group. They were followed for an average of more than seven years, with cancer data collected from a national registry. During the period, 68,775 women were diagnosed with cancer.
Having a daily drink was associated with 11 additional breast cancers per year per 1,000 women, one additional cancer of the oral cavity and pharynx, one additional cancer of the rectum, and 0.7 additional cases each for esophageal, laryngeal and liver cancers.
That totaled 15 additional cancer cases beyond the background rate of 118 cancers per 1,000 women. Taking a second drink every day brought the number to 30 cases, and a third brought it to 45 cases. Among the women studied, fewer than 2% had more than three alcoholic drinks per day.
The increased risk was not related to the type of alcohol consumed.
The chief limitations of the study were that it relied on the women’s recall of their alcohol consumption and that it had no data on overall mortality, Lauer and Sorlie said. But those problems are largely offset, they concluded, by the very large number of women in the study.