Older women who drink above 30g alcohol a day may have an elevated risk of endometrial cancer, a new study suggests.

Endometrial cancer begins in the lining of the uterus, and certain factors that raise a woman’s lifetime exposure to estrogen are thought to contribute to the disease. Obesity, late menopause and early menarche (the beginning of menstruation) have been linked to a heightened risk of endometrial cancer.

Alcohol has been shown to raise postmenopausal women’s estrogen levels -- a fact that may explain the new findings, according to the study authors.

While the link between alcohol and endometrial cancer needs to be confirmed in other studies, the current results underscore the potential risks of too much alcohol, according to Dr. Veronica Wendy Setiawan, an assistant professor of preventive medicine at the University of Southern California in Los Angeles.

“Moderation is the key,” she said.Setiawan and her colleagues report the findings in the International Journal of Cancer.

The findings are based on data from 41,574 postmenopausal women who reported their drinking habits and other lifestyle and health factors when they entered the study. Over the next eight years, 324 women developed endometrial cancer.

Overall, the researchers found, women who averaged two or more alcoholic drinks (a US drink is 14g) a day were twice as likely to develop the cancer as non-drinkers were. No such risk was seen among lighter drinkers.

The findings don’t prove a direct cause-and-effect relationship. But, the researchers note, they are in line with studies showing that alcohol spurs an increase in blood estrogen levels in postmenopausal women.

Because the current study did not include premenopausal women, it’s not possible to speculate about the possible effects of alcohol on younger women’s long-term risk of endometrial cancer, according to Setiawan.

However, she noted, there is evidence that younger women who drink relatively heavily -- about two drinks or more a day -- have higher estrogen levels than non-drinkers do.

Source: International Journal of Cancer, November 1, 2007.