MONDAY, Oct. 18 (HealthDay News) -- People with a genetic predisposition to basal cell carcinoma -- the most common form of skin cancer -- may trade one health risk for another, a new study suggests.
Because people with basal cell nevus syndrome (BCNS) tend to develop multiple basal cell skin cancers in early adulthood and so take more precautions against sun exposure, they may also run a higher risk of being deficient in vitamin D, report researchers in the October issue of Archives of Dermatology.
"We found that patients with skin cancer who practice very good photoprotection [sun protection] have lower vitamin D levels," said Dr. Jean Tang, lead author of the study. "This makes sense because they're avoiding sunlight and sun is required to synthesize vitamin D."
But having healthy levels of the nutrient may be necessary to protect against cancer, broken bones, heart disease and even some autoimmune diseases.
The study authors looked back at the medical records of 41 patients with BCNS who had previously been involved in a trial to see if the non-steroidal anti-inflammatory drug Celebrex (celecoxib) might prevent against basal cell carcinomas. According to the authors, Celebrex is not known to affect vitamin D levels in the body.
These individuals were matched against 360 men and women who did not have the cancer syndrome but who were of similar ages, similar weight, similar UV (ultraviolet) exposure and who lived in similar geographic areas
Eighty percent of the BCNS patients said they used sunscreen every day, avoided the sun during its hottest hours in the middle of the day and wore long-sleeved clothing.
And in this sample, 56 percent of participants with BCNS had too-low levels of vitamin D -- three times as many as in the control group.
"Most likely," said Tang, "the fact that skin cancer patients avoid sunlight is probably the number-one contribution to why they have low vitamin D levels, because the major difference between the two groups was that the skin cancer patients were practicing good photoprotection."
But at this point, the evidence for a link between sun protection and vitamin D deficiency is still an indirect one, said Dr. Vijay Trisal, an assistant professor of surgical oncology at City of Hope Cancer Center in Duarte, Calif., who was not involved in the study.
He also noted that a large number of people both with and without histories of skin cancer have vitamin D levels that are deficient.
Rather than basking in the sun or trading long-sleeved shirts for sleeveless, the authors suggest that wider screening of vitamin D levels would be a first step in resolving this problem. Vitamin D supplementation for those who are deficient could follow, said Tang, who is assistant professor of dermatology at Stanford University Medical Center.
Right now, the recommended daily allowance of vitamin D is 400 international units, but the Institute of Medicine is currently revisiting those numbers. A new report is expected at the end of November, Tang said.
The bottom line, according to Trisal: "It's easy to get adequate doses of vitamin D by taking a tablet."
Find out more about the vitamin D-skin cancer connection at the Skin Cancer Foundation.
SOURCES: Jean Y. Tang, M.D., Ph.D., assistant professor of dermatology, Stanford University Medical Center; Vijay Trisal, M.D., assistant professor of surgical oncology, City of Hope Cancer Center, Duarte, Calif.; October 2010 Archives of Dermatology
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