Vitamin D, Calcium Combo May Halve Melanoma Risk in Some Women
Supplements only benefited those who had had another form of skin cancer, study found
Posted: June 28, 2011
By Steven Reinberg
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 said.
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 said.
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 men.
“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 placebo.
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.
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