Cancer-Fighting Vitamin D
Aug. 22, 2000 (Washington) -- A chemically modified version of vitamin D may be a viable option for the prevention of skin cancer, according to research presented Wednesday at a national meeting of the American Chemical Society, the world's largest scientific society.
Vitamin D, often called the "sunlight vitamin," is a hormone manufactured by the body when the skin is exposed to ultraviolet B (UVB) radiation. In its natural form, it plays an essential role in the metabolism of calcium and phosphorus, helping build strong bones and teeth.
For almost a decade, scientists have suspected that Vitamin D also may play a large role in the prevention and treatment of various cancers. But research into its effects has been stymied by one seemingly insurmountable obstacle: The amounts needed to realize its cancer-fighting benefits in many cases also could lead to osteoporosis, a dangerous decrease in bone mass.
Now, researchers are developing novel substances tailored to preserve the cancer-fighting effects of vitamin D, while preventing its potentially lethal effects at higher doses. The results presented Wednesday were from a study conducted at Johns Hopkins University in Baltimore, where researchers have developed four possible drug candidates -- all variations of vitamin D.
In developing the four compounds, the researchers had one primary goal, lead investigator Gary Posner, PhD, tells WebMD. This goal was to single out the vitamin's growth properties while preventing it from drawing calcium into the bloodstream, a natural function of vitamin D. High doses of the vitamin could result in dangerously elevated levels of calcium, a condition that causes hormonal imbalances and osteoporosis, he says. Posner, PhD, is an endowed professor of chemistry at Johns Hopkins.
While additional animal studies must be conducted before human testing can even begin, Posner adds that the Hopkins team appears to have succeeded. After a 20-week treatment period, the most promising drug candidate reduced the incidence of tumors by 28% and the number of tumors by 63% in a group of mice painted with a tumor-inducing chemical, when compared to a group of untreated mice, he tells WebMD.
But despite having worked on the development of these substances for more than six years and on the development of these specific compounds for more than two years, Posner still harbors some significant reservations. "It is enormously gratifying to find compounds that we designed rationally show promise in the treatment of cancer. However, you must recognize that this is an early clinical test," he says, while noting that future studies may uncover new obstacles.
For example, future studies on larger animals and humans may yet reveal unexpected, potentially dangerous side effects, such as liver damage, he says. Similarly, although this study demonstrated that vitamin D may reduce the incidence of skin cancer in mice, future studies may not show the same level of effectiveness, he says.
"Hope is there," says Posner, citing the rapidly growing body of literature regarding vitamin D's potential cancer-fighting properties. "But there are a lot of hurdles out there," adds Posner, whose team already has begun to conduct additional studies on larger animals in hopes of developing a commercially viable drug within the next decade.