Study: Skin cancer patients show vitamin D insufficiency, deficiency

Key Points

National report - Researchers studying the link between photoprotection adherence and vitamin D levels in skin cancer patients did not find an association between these two parameters, but did find that melanoma and nonmelanoma skin cancer patients seemed to have a tendency toward vitamin D insufficiency and deficiency.

"In our small study we found a high prevalence of vitamin D insufficiency, at around 50 percent, and deficiency, at around 20 percent," says lead author Laura K. Delong, M.D., M.P.H., chief resident, department of dermatology, Emory University School of Medicine, Atlanta. "Dermatologists ... should be aware that many skin cancer patients they see may have low vitamin D levels ... and those might warrant monitoring."

Subjects answered surveys measuring demographics, skin cancer characteristics and sun-protection habits. Researchers included questions about the use of sunscreen, protective clothing, hats, sunblock, umbrellas or shade seeking. They also asked about any daily vitamin D supplementation: including a multivitamin, calcium and vitamin D, fish oil, or low-dose (400-1000 IU) vitamin D and D-rich food consumption to assess dietary intake. They then drew subjects' blood to measure serum 25(OH)D levels - the standard test to assess vitamin D status, according to Dr. Delong.

Most subjects Caucasian

Dr. Delong notes that 99 percent of the subjects were Caucasian and about 55 percent were melanoma patients. The authors defined deficient as vitamin D levels of 20 ng/mL or lower and insufficient as 30 ng/mL or lower.

"The mean 25(OH)D levels were 28 ng/mL in the adherent group and 29 ng/mL in the nonadherent group, which is not a statistically significant difference," she says. "However, we found that those who were taking a daily vitamin D supplement had a mean 25(OH)D of 31 ng/mL versus 25 ng/mL in those who were not. So, vitamin supplementation increased vitamin D levels to a close to sufficient level."

Subjects were getting only an average 200 IU daily from their diets, according to the study. The authors also found a trend, though not statistically significant, toward lower vitamin D levels in subjects with melanoma versus nonmelanoma skin cancers.

Dr. Delong and colleagues controlled for variables such as age, gender and education, in a linear regression with vitamin D as the outcomes variable.

"We found that vitamin D supplementation was a statistically significant predictor of vitamin D levels, as was age, which has been shown in previous studies," Dr. Delong says.