Abstract A79: Vitamin D status and breast cancer aggressiveness among African American and European American women in South Carolina

Abstract

Abstract Background and Significance: Racial disparities exist in breast cancer, with African-American (AA) women being diagnosed with more aggressive disease and exhibiting higher mortality than their European-American (EA) counterparts. Vitamin D is of interest in breast cancer prevention and prognosis because of its ability to inhibit cell proliferation and induce apoptosis and differentiation in both normal and malignant breast cells. Circulating 25hydroxyD [25(OH)D] concentrations in humans are a measure of vitamin D status, and vary based on sun exposure, dietary intake, supplement use, skin tone, age, and body mass index [BMI = weight(kg)/height(m)2], among other factors. This study examines racial differences in vitamin D status and the association between serum 25(OH)D and clinical parameters among women diagnosed with breast cancer in South Carolina. Methods: A total of 107 women between 33 and 84 years of age and diagnosed with breast cancer in the previous five years were enrolled in the study (n=60 AA, n=47 EA). Each participant donated a blood sample, and serum 25(OH)D was measured by enzyme immunoassay. Age, BMI, clinical characteristics, and treatment were abstracted from medical records. Results: The mean (±SD) concentration of serum 25(OH)D in EA women was 29.8 ± 12.1 ng/ml while the mean concentration in AA women was 19.3 ± 10.0 ng/ml. Vitamin D deficiency (defined as serum 25(OH)D <20ng/ml) was much more common among AAs (60%) compared with EAs (15%). Serum 25(OH)D concentrations decreased with increasing stage of disease and were lowest among women who were triple (ER/PR/HER2) negative compared with other groups. Women who were vitamin D deficient were 8 times more likely to be diagnosed with aggressive disease (defined as regional or distant stage) as compared to women who were sufficient in vitamin D, though the confidence interval was wide, indicating imprecision of the result (OR=8.6,95%CI=1.8,41.2, after adjustment for age, race, BMI, season and months since diagnosis). Conclusions: This study corroborates other research showing racial differences in vitamin D status and provides further support for a protective role of vitamin D in breast cancer, particularly for highly aggressive disease. The prevalence of vitamin D deficiency and insufficiency was high, suggesting the need for monitoring of vitamin D levels among breast cancer patients. This work was supported by grants from the National Cancer Institute, Center to Reduce Cancer Health Disparities (Community Networks Program) to the South Carolina Cancer Disparities Community Network (SCCDCN) [1 U01 CA114601] and the Cancer Center of the University of South Carolina. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A79.