New vitamin D research will impact Cancer Society guidelines review

National report - More than a year into reviewing its sun protection guidelines, the American Cancer Society is now pondering the possible impact of new information about vitamin D.

New research indicates that the vitamin, which the body produces from exposure to the sun's ultraviolet rays, may help prevent - and even serve as treatment for - lymphoma and cancers of the colon, lung and prostate, according to Dr. Edward Giovanucci, M.D., a Harvard University professor of medicine and nutrition.

Dr. Giovanucci, who discussed current research at the 96^th Annual Meeting of the American Association for Cancer Research, says vitamin D may even help prevent skin cancer - contrary to the warnings of groups such as the Cancer Society that strongly recommend that people limit their exposure to the sun.

"It's a factor we'll have to take up," says Robert A. Smith, Ph.D., director of cancer screening for the society.

The society expects to publish its revised guidelines by early autumn.

UV, food are sources

Research shows that vitamin D, also called the sunshine vitamin, is most easily produced by exposure to UV rays; it also can be acquired from food and supplements, but not as efficiently.

Dr. Giovanucci says his research suggests that vitamin D might help prevent 30 deaths for each one caused by skin cancer.

Dr. Giovanucci's claims were reported in an Associated Press (AP) story in May - the Cancer Society's Skin Cancer Awareness Month. The AP reported that the claims had motivated the Cancer Society to revise its sun protection guidelines. The AP later issued a revision stating the Cancer Society's guidelines review had been under way for more than a year.

Still, Dr. Smith says that Dr. Giovanucci's published comments about vitamin D's ability to prevent and treat many types of cancers are convincing.

"Dr. Giovanucci did a good job of getting his message across in his keynote address at that conference, and the evidence he presented is pretty persuasive," Dr. Smith says. "Our guidelines have to consider downsides as well as the benefits. We know, for instance, that people need physical activity, but does that conflict with the suggestion to not go out in the strong mid-day sun? For women, if more cosmetics are including sun protection, does that mean women using those cosmetics are getting too little sun?

"Now we have Dr. Giovanucci's new vitamin D research, and some are saying people should be exposing their skin more to the sun," he says. "This is a dimension of the guidelines that has to be examined and addressed."

Dr. Smith notes that this sort of dilemma is not uncommon in the medical world. He cites the example of screening tests for colorectal cancer, noting that these tests sometimes cause more problems than the potential disease itself.

"It's important to reconcile the benefits versus the potential harm," he says. "Our job in revising the guidelines is to reconcile the various opinions."

Derms urge caution

In the opinion of some dermatologists, there is little debate, regardless of the new evidence put forth in Dr. Giovanucci's presentation.

"No one disputes that vitamins are good for you, and no one disputes that vitamin D is good for you," says Darrell S. Rigel, M.D., clinical professor of dermatology at New York University Medical Center. "The issue is, how do you get enough vitamin D? How much exposure to the sun is enough, and how much is too much? What we do know is this - one American dies every hour of skin cancer, and one of the main causes of skin cancer is overexposure to ultraviolet radiation - a known and proven carcinogen."