Coffee may protect against womb cancer: Study

By Dr. Ananya Mandal, MDNov 22 2011

A new study shows that regular intake of coffee may significantly lower risk for endometrial or womb cancer.

For the study the researchers looked at coffee consumption and endometrial cancer risk in more than 67,000 women aged between 34 and 59 enrolled in the long-running Nurses' Health Study. The researchers found that women who took more than four cups of coffee a day over a 26-year period were 25 percent less likely to get the cancer. Women who drank two to three cups a day were 7 percent less likely to get it. Drinking less than four cups a day was not associated with reduced risk. Furthermore drinking tea did not reduce the risk. Additionally drinking more than two cups of decaffeinated coffee a day was tied to a 22 percent reduced risk for endometrial cancer.

“It would be premature to make a recommendation that women drink coffee to lower their endometrial cancer risk,” study author Dr. Edward Giovannucci, professor of nutrition and epidemiology at Harvard School of Public Health, told Reuters. He said in a written statement that coffee contains more antioxidants than most fruits and vegetables but pointed out that the study only links coffee and reduced risk of endometrial cancer and doesn't prove that coffee prevents the cancer. What's more, the authors concluded that adding lots of sugar and cream to coffee might offset any potential benefits.

The benefit wasn't a complete surprise, since coffee has been shown to lower estrogen and insulin levels, and higher levels of these hormones have been associated with an increased risk of endometrial cancer. But the new findings do help to clarify how obesity, estrogen and coffee might interact in triggering tumors.

In the study, obese women were more likely than lean women to show a coffee-associated drop in endometrial cancer risk. That may be due to the fact that, particularly after menopause, most of the estrogen a woman's body makes is in the fat cells — so coffee's estrogen-lowering effects may be more dramatic among women with more fat and, thus, more estrogen.

“The effect of coffee on estrogen and insulin seem to be due to other components in coffee that aren't related to caffeine,” says Giovannucci. “There does seem to be a benefit that could be achieved through decaffeinated coffee too.” He warns however, “It would be the completely wrong message if people thought that if coffee is good, then they might get the same benefit from caffeinated soft drinks.”

The study was published in the journal Cancer Epidemiology, Biomarkers & Prevention. Coffee has been shown to protect against diabetes, Giovannucci said in the statement. And according to another Harvard researcher, Dr. Rob van Dam, coffee has also been linked to reduced risk for depression in women as well as other benefits.

The bottom line, the researcher said, is that “people who are already enjoying their coffee” can probably continue to do so. But it's too early to recommend that anyone start drinking coffee hoping to get health benefits.

Dr. Janice Dutcher, director of immunotherapy at St Luke's Roosevelt Hospital Center and Beth Israel Medical Center in New York City, suggested the findings should not been interpreted as anything more than an “interesting hypothesis.”

“I'm skeptical,” she said. “My skepticism comes from the fact that a variety of things have been associated with cancer at one point, and then not associated with cancer later on. Twenty years ago it was thought coffee was the cause of pancreatic cancer. And to isolate one dietary factor from all the other things that people take in is very complicated. So while I'm sure this is a carefully done study with good methodology, I would be very careful about drawing any conclusions.”

“If a woman drinks coffee currently, this may be one benefit,” Marji McCullough, strategic director of nutritional epidemiology for the American Cancer Society ACS, told Reuters Health in an email. But McCullough added that further studies are needed - in part to see whether coffee has different effects on endometrial cancer risk in different groups of women. She pointed out that in this study, the link between coffee and lower cancer risk was weaker among women who had never smoked, versus those who had. According to the ACS, the average U.S. woman has about a one in 40 chance of developing endometrial cancer in her lifetime.

Both McCullough and Giovannucci said that one of the best things women can do to curb their risk of endometrial cancer is to maintain a healthy weight though diet and regular exercise. “Even if the coffee finding is causal,” Giovannucci said, “the most important thing would be weight management through diet and exercise.”

Endometrial cancer is the cancer of the lining of the womb. In 2011, the disease will strike an estimated 46,470 women in the U.S. and will result in an estimated 8,120 deaths.