Study Title:

Vitamin D and Breast Cancer Risk

Study Abstract

Vitamin D has been associated with decreased risk of several cancers. In experimental studies, vitamin D has been shown to inhibit cell proliferation and induce differentiation and apoptosis in normal and malignant breast cells. Using a population-based case-control study on Long Island, New York, we examined the association of breast cancer with plasma 25-hydroxyvitamin D (25-OHD) levels, a measure of vitamin D body stores. In-person interviews and blood specimens were obtained from 1,026 incident breast cancer cases diagnosed in 1996 to 1997 and 1,075 population-based controls. Plasma 25-OHD was measured in batched, archived specimens by Diasorin RIA. The mean (SD) plasma 25-OHD concentration was 27.1 (13.0) and 29.7 (15.1) ng/mL in the cases and controls, respectively (P < 0.0001). Plasma 25-OHD was inversely associated with breast cancer risk in a concentration-dependent fashion (Ptrend = 0.002). Compared with women with vitamin D deficiency (25-OHD, <20 ng/mL), levels above 40 ng/mL were associated with decreased breast cancer risk (odds ratio, 0.56; 95% confidence interval, 0.41-0.78). The reduction in risk was greater among postmenopausal women (odds ratio, 0.46; 95% confidence interval, 0.09-0.83), and the effect did not vary according to tumor hormone receptor status. In summary, these results add to a growing body of evidence that adequate vitamin D stores may prevent breast cancer development. Whereas circulating 25-OHD levels of >32 ng/mL are associated with normal bone mineral metabolism, our data suggest that the optimal level for breast cancer prevention is ≥40 ng/mL. Well-designed clinical trials are urgently needed to determine whether vitamin D supplementation is effective for breast cancer chemoprevention.

From October 2010 press release:

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.

Study Information

Katherine D. Crew, Marilie D. Gammon, Susan E. Steck, Dawn L. Hershman, Serge Cremers, Elzbieta Dworakowski, Elizabeth Shane, Mary Beth Terry, Manisha Desai, Susan L. Teitelbaum, Alfred I. Neugut, and Regina M. Santella
Association between Plasma 25-Hydroxyvitamin D and Breast Cancer Risk
Cancer Prev Res
2010 June
Department of Medicine, Division of Hematology/Oncology, Columbia University

Full Study

http://cancerpreventionresearch.aacrjournals.org/content/2/6/598.full