MONDAY, June 27 (HealthDay News) -- Certain women at risk for
developing melanoma, the most severe form of skin cancer, may cut
the likelihood in half by taking vitamin D/calcium supplements, a
new study suggests.
"It looks like there is some promising evidence for vitamin D and calcium for prevention of melanoma in a high-risk group," said lead researcher Dr. Jean Tang, an assistant professor of dermatology at Stanford University School of Medicine.
The women most at risk of developing the life-threatening cancer
are those who have had a previous non-melanoma form of skin cancer,
such as basal cell or squamous cell cancer, the researchers
Vitamin D and calcium are well-known for their roles in bone
growth, but they also affect other cells in the body. Some studies
have shown that vitamin D and calcium are associated with lower
risk of colon, breast, prostate and other cancers, the researchers
Tang speculated that cancer cells lurking in the skin of women
who have had a previous skin cancer may be waiting to develop into
melanoma. "But if they take calcium and vitamin D that reduces the
risk of developing an actual tumor," she said.
As little as 400 international units (IU) of vitamin D daily may
be protective, Tang said. The U.S. Institute of Medicine now
recommends 600 IU of vitamin D daily, she added.
Calcium has also been shown to reduce tumor growth in patients
with colon cancer, Tang said. "So maybe calcium has a role, too,"
she said. "I can't say whether it was the calcium or the vitamin D
that was important."
But the combination seemed to convey a benefit, she added.
Whether these results would be seen in men or young women isn't
known, Tang noted. But an earlier study led by Tang found a benefit
from vitamin D in reducing the risk of melanoma among older
"More studies need to be done, because we want to make sure these results are true in other communities," Tang said.
The report was published in the June 27 online edition of the
Journal of Clinical Oncology.
For the study, Tang's team collected data on 36,282
postmenopausal women, 50 to 79 years old, who took part in the
Women's Health Initiative study. As part of a test to see if
calcium plus vitamin D had any effect on hip fractures or colon
cancer, the women were randomly assigned to take supplements or
The supplements were 1,000 milligrams of calcium and 400 IU of
vitamin D daily.
Over about seven years of follow-up, the women taking the
supplements who had had previous non-melanoma skin cancer reduced
their risk of developing melanoma by 57 percent, compared with
similar women not taking the supplements.
The melanoma risk reduction was not seen among women who had not
had an earlier non-melanoma skin cancer, the study authors
Overall, only 176 cases of melanoma developed, said the
In the United States, more than 68,000 cases of melanoma are
diagnosed in adults each year, according to the U.S. National
Hoping to uncover why vitamin D and/or calcium may be
beneficial, Tang said the team next intends to test the compounds
directly on cancer cells.
Commenting on the study, Dr. Michael Holick, professor of
medicine, physiology and biophysics at Boston University School of
Medicine, said a lot of sun exposure early in life increases the
risk for non-melanoma skin cancer, but may actually lower the risk
of developing melanoma. Sunlight is a source of vitamin D.
"Melanoma is a different story. Being exposed to sunlight, making some vitamin D may very well be protective of melanoma," Holick said. "The thinking is, improving your vitamin D status, whether by supplements or by exposure to sunlight, you are providing your skin cells with a mechanism to prevent them from becoming malignant," he said.
What role calcium may play is unknown, Holick said. "We don't
know whether vitamin D can have its effect in the absence of
calcium or vice versa; there's rationale for both," he said.
Holick said he thinks the finding would be the same for men and
People can get their vitamin D from diet, sun exposure and
supplements. Fatty fish and fortified dairy products are two
dietary sources of vitamin D.
Holick said he recommends that children take 1,000 IU of vitamin
D a day and adults, 2,000 IU.
For more information on skin cancer, visit the
U.S. National Library of Medicine.