MONDAY, Aug. 15 (HealthDay News) -- The higher a person's vitamin D levels, the higher the risk of non-melanoma skin cancer, such as basal cell carcinoma and squamous cell carcinoma, finds new research.
But the study, appearing in the Aug. 15 issue of the Archives of Dermatology, stops short of saying that high vitamin D levels might actually cause these types of cancer, the most common malignancies in the United States.
And because ultraviolet (UV) radiation exposure is necessary for vitamin D production in the body, it might simply mean that people with more sun exposure tend to develop more non-melanoma skin cancers. It's unclear whether it's the damage from UV rays that accounts for the risk, or rising vitamin D levels that accompany exposure to the rays.
"This adds to the murky water [surrounding the relationship between vitamin D and skin cancer]," said Dr. Vijay Trisal, assistant professor of surgical oncology at City of Hope Cancer Center in Duarte, Calif. "Is it vitamin D or sun exposure? The two go hand-in-hand."
Other scientists have investigated a possible relationship between vitamin D and skin cancer, but so far the results have been limited and conflicting.
One study suggested that higher vitamin D levels might actually protect against skin cancer. This could be because vitamin D may inhibit a pathway involved in cancer, said Dr. Melody Eide, a dermatologist with Henry Ford Hospital in Detroit, and lead author of the current study.
But two other studies had results suggesting the opposite.
Eide and colleagues based their findings on 3,223 mostly female, white patients in a Detroit health maintenance organization who had visited a doctor either because they had osteoporosis or low bone density.
Many more patients (2,257) had too-low levels of vitamin D than had adequate levels (966).
Over a follow-up period of al
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