MUSC doctors look at vitamin D's effect on early-stage prostate cancer

Vitamin D kills prostate cancer cells in the laboratory. Now, specialists at the Hollings Cancer Center at the Medical University of South Carolina are studying whether vitamin D will halt the cancer's progression in early-stage patients.

Drs. Sebastiano Gattoni-Celli and David Marshall hope to add a large dosage of vitamin D to "watchful waiting."

Watchful waiting is an approach some men with slow-growing prostate cancer choose. Doctors monitor the disease for signs of growth. If and when that occurs, treatment may be sought.

"We offer something more than monitoring," said Gattoni-Celli, principal investigator.

That "something more" is vitamin D — a nutrient mainly absorbed through sun exposure and long touted as a cancer-prevention agent.

The prostate is a walnut-sized gland below the bladder responsible for making and storing fluid that transports sperm. The gland is known to sequester vitamin D, which helps it function.

The recommended daily dose of vitamin D for men ages 51 to 70 is 400 International Units, or IUs. Study participants take 4,000 IUs of vitamin D daily.

The Food and Drug Administration approved the study-prescribed dosage as having minimal to no toxicity, said Gattoni-Celli, who has taken 4,000 IUs of vitamin D daily for three years.

"A good number of people may be deficient in vitamin D because we live and work indoors," he said.

Participants in the watchful waiting and vitamin D study are monitored every eight weeks. If their levels of prostate-specific antigen — a protein found in blood that correlates with prostate cancer — rise twice consecutively, they will be counseled to reassess their treatment options.

Vitamin D is found in fortified milk, eggs and fatty fish, but people absorb most of what they need through ultraviolet rays. Fifteen minutes of sun exposure twice a week to the face, arms, hands or back without sunscreen is sufficient for most people to produce enough vitamin D, according to the National Institutes of Health.

People with dark skin might have difficulty getting enough vitamin D from the sun. Increased melanin, which gives dark skin its color, reduces the skin's ability to synthesize the vitamin from sunlight.

Gattoni-Celli said he is not surprised by the fact that prostate cancer affects black men disproportionately. "The hunch is there," he said about a link between vitamin D and prostate cancer, but the reality of collecting scientific evidence requires patience.

Patients can opt out of the study any time to pursue treatment, said Marshall, the study's co- investigator. The only risk of watchful waiting is that treatment later might prove more complex than if used earlier, he said.

Watchful waiting is advisable because some forms of prostate cancer can proceed very slowly, Gattoni-Celli said.

Autopsies of older men who died of causes other than prostate cancer revealed that 50 percent of them had the disease, Gattoni-Celli said.

Some experts now worry that prostate cancer might be overdiagnosed and overtreated with the increased availability of prostate-specific antigen screening in the last 25 years. Men who otherwise might have lived the rest of their lives without suffering symptoms of the disease now could be receiving aggressive treatment.

Some prostate cancer patient advocates are critical of the watchful waiting approach, however.

Bob Strobel leads the Charleston chapter of Us TOO, a prostate cancer education and support group. "Anytime someone mentions watchful waiting to someone with prostate cancer, you'll see them get irate," he said.

Strobel pointed to advances in treatments. "The things that are happening now with medical treatment, it's astounding," he said.

Treatments include the surgical removal of the gland, radiation and hormone therapy. Doctors also can implant radioactive seeds into the gland or freeze the cancer. All treatment options can cause problems such as incontinence and erectile dysfunction.

Reach Jill Coley at 937-5719 or jcoley@postandcourier.com.