Summary: According to a new study published by Harvard University researchers, drinking at least one cup of coffee per day can lower a woman’s risk for developing endometrial cancer. Using data from 16 studies, in what is called a meta-analysis, the results showed that women who drank 3 to 4 cups of coffee per day had nearly 30% lower risk of endometrial cancer compared with women who drank little or no coffee. Each additional cup conferred about an 8% risk reduction. Coffee contains hundreds of bioactive compounds that may contribute to a lower cancer risk. For endometrial cancer, substances in coffee that lower estrogen levels may play a role.

Researchers at the Harvard School of Public Health and Brigham and Women’s Hospital, Boston, recently reported findings showing that women who drink at least one cup of coffee per day have a significantly reduced risk of endometrial cancer [1]. Endometrial cancer is the most common gynecologic malignancy in the United States, and has been associated with obesity and elevated levels of both estrogen and insulin, which promote the growth of endometrial cells. Studies have shown that coffee can modulate hormone levels and overcome insulin resistance, a precursor of diabetes and an important risk factor for endometrial cancer.

The Harvard researchers conducted a meta-analysis of 16 studies involving coffee consumption and cancer risk from the United States, Europe and Japan. A total of 6,628 cases of endometrial cancer were identified from the studies. The results showed that, overall, women who drank 3 to 4 cups of coffee per day had a 29% reduced risk of endometrial cancer compared with women who drank little or no coffee. Each additional cup of coffee consumed was associated with about an 8% further risk reduction. The association was strongest among Japanese women, possibly because of the lower use of hormone replacement therapy compared with U.S. and European women.

Coffee contains hundreds of bioactive substances, many of which may play a role in the lower prevalence of several major cancer types observed among regular coffee drinkers. Certain phenolic compounds found in coffee, such as chlorogenic acid, have strong antioxidant properties that can repair damage to DNA in cells, improve insulin sensitivity, and inhibit glucose absorption in the intestine [2]. Other phenols, including kahweol, a substance concentrated in unfiltered coffees like French press and Turkish/Greek coffee, have antiangiogenic (suppresses the growth of tumor blood vessels) and anti-inflammatory activities [3]. Caffeine has been reported to modulate estrogen levels, which is a key factor in endometrial cancer.

As with any non-randomized, non-controlled study, there is the possibility that the results of this meta-analysis could be subject to recall bias, lack of standardization of coffee preparation or variety, and the influence of confounding factors, such as smoking and body mass index. Nonetheless, these results provide compelling evidence that regular or high coffee consumption may lower a woman’s risk for endometrial cancer.

By Roderick Smith, M.S.

1. Je Y, Giovannucci E. Coffee drinking and risk of endometrial cancer: findings from a large up-to-date meta-analysis. Int J Cancer. Published online ahead of print.

2. Arnlov J, Vessby B, Riserus U. Coffee consumption and insulin sensitivity. JAMA, 2004;291:1199–201.

3. Cárdenas C, Quesada AR, Medina MA. Anti-angiogenic and anti-inflammatory properties of kahweol, a coffee diterpene. PLoS ONE 2011;6(8):e23407.