Associations between vitamin D deficiency and risk of aggressive breast cancer in African-American women

The Journal of Steroid Biochemistry and Molecular Biology, Available online 18 September 2012
Song Yao, Christine B. Ambrosone Christine.Ambrosone@roswellpark.org
Department of Cancer Prevention and Control, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY 14263

Although breast cancer incidence in the US is highest for women of European ancestry (EA), women of African ancestry (AA) have higher incidence of cancer diagnosed before age 40 and tumors with more aggressive features (high grade and negative for estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor (HER2)), which precludes targeted therapies and leads to poorer outcomes. It is unclear what underlies these disparities.

It has been hypothesized that dark skin with high melanin content is the ancestral skin color of origin, with adaptation to northern environs resulting in lighter skin. Although intense sunlight in sub-Saharan Africa may compensate for low sun absorption through skin, an urban or western lifestyle may result in less synthesis of vitamin D with higher skin pigmentation.

Laboratory and preclinical data indicate that vitamin D is involved in preventing breast carcinogenesis and progression. Vitamin D receptor (VDR) knock-out mice are more likely to develop tumors that are ER-negative, and we have shown that serum levels of 25OHD are lowest among EA women with triple-negative tumors (negative for ER, PR and HER2); and among non-cancer patients, vitamin D levels are lower in AAs than in Eas.

Thus, it is plausible to hypothesize that low vitamin D levels could be associated with the higher prevalence of more aggressive tumors among AA women. In this paper, we review the current literature on vitamin D and aggressive breast cancer subtypes, discuss vitamin D in AA women from a perspective of evolution and adaption, and examine the potential role of vitamin D in cancer racial disparities. We present our recently published data showing two single nucleotide polymorphisms in vitamin D catabolic enzyme CYP24A1 associated with higher risk of estrogen ER-negative risk in AA than in EA women. The relationship of vitamin D with breast cancer risk may be subtype-specific, with emerging evidence of stronger effects of vitamin D for more aggressive breast cancer, particularly in women of African ancestry.

Highlights

• Results from previous studies of vitamin D and breast cancer risk are inconsistent
• Vitamin D may exert stronger effects against aggressive breast cancer subtypes
• Vitamin D levels are lower in African-Americans than in European-Americans
• African-American women are at high risk of aggressive breast cancer
• Vitamin D may be related to breast cancer racial disparities in the US

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See also VitaminDWiki

• Overview Cancer and vitamin D
• Overview Dark Skin and vitamin D
• All items in category Breast Cancer and vitamin D 259 items
• Triple-negative breast cancer is 3X more frequent if less than 32 ng of vitamin D – March 2012
• Overview Breast Cancer and Vitamin D