Vitamin D Protects Against Endometrial Cancer

(Ivanhoe Newswire) ““ So far in 2010, 7,950 people have died from endometrial cancer and there are 43,470 new cases. Studies on animals showed that obese women, who are at a higher risk for endometrial cancer, should take vitamin D to reduce their risk.

The study showed that 25 percent of obese mice given vitamin D supplements in their diet developed endometrial cancer, while 67 percent of mice not given vitamin D developed cancer. Vitamin D did nothing for mice of normal weight, whether or not they took vitamin D supplements. All of the mice were already at an increased risk for cancer because they lost one of two PTEN tumor suppressor genes, and without both they are at a much higher risk for human endometrial cancer.

“Vitamin D has been shown to be helpful in a number of cancers, but for endometrial cancer, our study suggests it protects only against cancer that develops due to obesity,” the study’s lead investigator, Leena Hilakivi-Clarke, PhD, a Professor of Oncology was quoted as saying. “Still, if these results are confirmed in women, use of vitamin D may be a wonderfully simple way to reduce endometrial cancer risk.”

“Until further studies are done, I think the best advice for women concerned about their risk is to take vitamin D supplements or spend a few more minutes each week in the sun. This vitamin has shown many health benefits in addition to the promise suggested by our mouse study,” explains Dr. Leena Hilakivi-Clarke.

It is best for women to remain at a healthy weight, not only to prevent endometrial cancer, but maintaining a healthy weight has many other health benefits. “However, since over 50% of women in the US are overweight or obese, and losing weight is difficult, other means are needed to prevent endometrial cancer in these women. One way is to use progesterone, but it increases breast cancer risk. Vitamin D supplements are likely to be safer than, for example, progesterone,” says Dr. Leena Hilakivi-Clarke.

Previous studies have shown that obesity in women increases human endometrial cancer by two to six times. Recent research published by the National Institutes of Health on the protective effects of vitamin D on endometrial cancer showed no overall benefit, but the study did not investigate whether vitamin D was effective in obese women, Dr. Hilakivi-Clarke says. For that reason, researchers focused on weight and endometrial cancer.

They used the best animal model available to look at endometrial cancer ““ the PTEN knock-out mice. “Loss of PTEN is a common event in endometrial cancer in women,” Hilakivi-Clarke says. The mice were divided into four groups: one group was fed a normal diet, another was fed a normal diet with vitamin D supplements, another was fed a high-fat diet, and the last group was fed a high-fat diet with vitamin D supplements.

The study showed that of the mice fed a high-fat diet, 67 percent developed endometrial cancer, while only 25 percent fed high-fat diets along with vitamin D developed it. “In the obese mice, vitamin D offered a very strong, very significant protective effect,” Hilakivi-Clarke says.

The researchers aren’t sure as to why vitamin D reduces the chance of endometrial cancer in obese mice, but they presume that obese mice produce less osteopontin, which makes cancer more aggressive. They also believe the obese mice are producing more E-cadherin, which stops cancer form metastasizing.

“But we really don’t know why dietary vitamin D works so well in our obese mice,” Hilakivi says. “We are currently investigating the mechanisms, and we are hopeful that we can find an answer.”

SOURCE: Cancer Prevention Research, published online September 20, 2010

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