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Doctors look at vitamin D effect on
cancer
by Jill
Coley
Of The
Post and Courier
Vitamin D kills prostate cancer cells in the laboratory. Now,
specialists at the Hollings Cancer Center at MUSC 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.
Vitamin D, prostate cancer
If you have been diagnosed with early-stage prostate cancer and are
considering “watchful waiting,” you may call 792-8303 to learn more
about participating in the Hollings Cancer Center study.
Editor’s note: The article ran
March 17 in the Post and Courier and is reprinted with permission.
Friday, March 21, 2008
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