Review
MIAMI BEACH, Fla. — Women diagnosed with aggressive and late stage breast cancer are more likely to have low levels of vitamin D compared with women with less dangerous forms of the disease, researchers reported here.
Women who were vitamin D deficient — with plasma concentration less than 20 ng/mL — were eight times more likely to be diagnosed with regional or distant spread of cancer when compared with women who had sufficient levels of the vitamin (OR 8.6, 95% CI 1.8 to 41.2), after statistical adjustments, according to Susan Steck, PhD, MPH, of the University of South Carolina in Columbia.
Severe vitamin D deficiency — plasma concentrations less than 10 ng/mL — were found in 17% of African-American women but not in any white participants, Steck reported here at the American Association for Cancer Research Conference on the Science of Cancer Health Disparities.
About 60% of African Americans with breast cancer who participated in the study had some level of vitamin D deficiency, compared with 14.9% of white women (P<0.0001).
Conversely, just 21.7% of African-American women had sufficient levels of vitamin D compared with 42.6% of white women, Steck and colleagues found.
“We think it may be important to for doctors to monitor the vitamin D blood levels of their patients, especially among African-American patients,” said Steck at a poster presentation.
“We know that darker skin pigmentation acts somewhat as a block to producing vitamin D when exposed to sunlight, which is the primary source of vitamin D in most people,” Steck told MedPage Today. She also noted that higher body mass index and physical activity can impact vitamin D levels.
Steck and colleagues recruited 107 women who were diagnosed with breast cancer in the previous five years. Sixty of these women were African American, while the remaining 47 were white. All women donated a blood sample, and vitamin D status was measured with circulating 25-hydroxyvitamin D (25-OH-D) levels. The mean serum concentration of 25-OH-D was 29.8 ng/mL in white women and 19.3 ng/mL in African-American women.
Serum levels were lowest among patients with triple-negative breast cancer — tumors lacking estrogen, progesterone, and HER2 receptors — and diagnosed in 17 African-American women and seven white women, though the disparity did not reach statistical significance, Steck said.
She said that doctors might want to check levels of vitamin D with their patients and discuss implications of the findings. However, she said further research is required to determine if vitamin D supplementation is worthwhile.
“Vitamin D has become the flavor of the month, with studies that indicate it might be useful in heart disease, cancer, and even Alzheimer’s disease. The question that emerges from these studies is, if we do intervene with vitamin D supplementation, will we improve things for patients?” said Olveen Carrasquillo, MD, chief of general medicine at the University of Miami.
“At one time we had similar thoughts about vitamin E, but when we did the clinical trials, it showed vitamin E had little influence on improving health,” he told MedPage Today. “We don’t know if vitamin D itself is the factor or if levels of vitamin D are markers of some other factor that is related to breast cancer.”
The study’s main statistical findings reflected adjustments for age, race, body mass index, season and months since diagnosis.
The study was funded by the National Cancer Institute.
Steck and Carrasquillo had no relevant financial disclosures.
Primary source: American Association for Cancer Research
Source reference:
Steck S, et al, “Vitamin D status and breast cancer aggressiveness among African-American and European-American women in South Carolina” AACR 2010; Abstract A79.
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