Long-term coffee consumption may be associated with a reduced risk for endometrial cancer, according to a study published online Tuesday in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.

Edward Giovannucci, professor of nutrition and epidemiology at the Harvard School of Public Health, said that coffee is emerging as a protective agent in cancers that are linked to obesity, estrogen and insulin.

"Coffee has already been shown to be protective against diabetes due to its effect on insulin," said Giovannucci, a senior researcher on the study. "So we hypothesized that we'd see a reduction in some cancers as well."

The researchers observed cumulative coffee intake in relation to endometrial cancer in 67,470 women who enrolled in the Nurses' Health Study. During the course of 26 years of follow-up, researchers documented 672 cases of endometrial cancer.

Drinking more than four cups of coffee per day was linked with a 25 percent reduced risk for endometrial cancer. Drinking between two and three cups per day was linked with a seven percent reduced risk.

A similar link was seen in decaffeinated coffee, where drinking more than two cups per day was linked with a 22 percent reduced risk for endometrial cancer.

Giovannucci said that he hopes this study will lead to further inquiries about the effect of coffee on cancer because in this and similar studies, coffee intake is self-selected and not randomized.