NIH News Advisory
National Institute of
Environmental Health Sciences

Wednesday, Dec. 11, 1996

Tom Hawkins
(919) 541-1402
Home: (919) 782-3009

Vitamin D Receptor Gene Variation Linked to
Reduced Prostate Cancer Risk In Study at NIEHS and UNC

Men with a particular wrinkle, or variation, in their vitamin D receptor genes appear to have only a third the risk of developing a prostate cancer requiring surgery, scientists at the National Institute of Environmental Health Sciences and the University of North Carolina at Chapel Hill have found.

Their study, in the journal Cancer Research, is the latest tantalizing suggestion of a possible role for vitamin D, from the sun or diet, in reducing prostate cancer risk, the second leading cancer killer of men. More than 40,000 men are expected to die of the disease this year.

NIEHS' Jack A. Taylor, M.D., Ph.D., and colleagues found that two alleles on the vitamin D receptor gene may affect the risk of prostate cancer. An allele is a slight, naturally occurring variation of a gene -- in this case, the gene which helps control how vitamin D is utilized by the body's cells.

Two alleles are inherited, one from each parent. They come in two forms designated by researchers as either T or t, so that each person ends up with one of three combinations, TT, Tt, or tt.

The study found that men inheriting the tt allele seem to enjoy one-third less likelihood of developing prostate cancer requiring surgery. Does the tt combination provide for better use of vitamin D? "We can't say yet, but we'll be pursuing an answer," Dr. Taylor said.

The alleles were studied in blood samples from 108 prostate surgery patients, less than 10 percent had tt and most had TT or Tt alleles, and from 170 male non-cancer patients at nearby hospitals of the University of North Carolina, Chapel Hill, N.C., and Duke University, Durham, N.C. Well under 10 percent of the prostate surgery patients had tt alleles, whereas about one in five of the controls did.

This study follows one in which other investigators found that men living in northern latitudes with less total sunlight exposure (and therefore less production of vitamin D by the skin) seem to have a higher incidence of prostate cancer.

Another study shows that vitamin D suppresses prostate cancer cells cultured in the laboratory. And a rodent study has suggested that vitamin D analogs may protect against prostate cancer.

Dr. Taylor said, "Together with these other studies, our findings support the idea that vitamin D plays an important role in prostate cancer, but it is too early to start applying these results to human prevention strategies or therapies.

"We certainly are not ready to suggest using vitamin D in prostate cancer prevention," Dr. Taylor said, "but we are very excited about trying to move this line of research forward to determine how the tt alleles may change the utilization of vitamin D."

NIEHS is one of the National Institutes of Health, most of which are in Bethesda, Md., but NIEHS is located in central North Carolina. Dr. Taylor is in the Epidemiology Branch of the Environmental Diseases and Medicine Program at NIEHS.

In 1995, other NIEHS researchers, in collaboration with scientists from Johns Hopkins University, identified and cloned a gene that suppresses the spread of prostate cancer. Like many other cancers, prostate cancer may result from interactions between a genetic susceptibility and environmental factors, such as smoking, diet and exposures to chemicals and radiation.