Abstract P6-09-02: Vitamin D Levels, Triple-Negative Breast Cancer, and Geography: A Retrospective Analysis of a Large Database of Oncology Practices in the United-States (US)

Abstract BACKGROUND: The UVB-vitamin D-breast cancer (BC) hypothesis is supported by ecological studies demonstrating an inverse correlation between sunlight exposure and BC incidence and mortality. Collective data from observational studies also favor an inverse association between vitamin D status and BC risk, recurrence and mortality. Yet, inconsistencies exist regarding the role of vitamin D in BC biology and its recently described association with triple-negative breast cancer (TNBC). Similarly, the validity of the vitamin D-latitude paradigm has also been disputed. In this study, we aimed to determine the existing associations between serum vitamin D levels, geographic distribution, clinical and pathological characteristics of BC patients (pts) across the US. METHODS: This was a retrospective analysis from the electronic health record database of pts diagnosed with BC between 1/2007-5/2013 across US Oncology Network practices. Practices were stratified based on their geographic location into one of three categories: northern (>40° N), central (35-40°N) and southern (<35°N) latitude. For each pt, we collected the following: age at diagnosis, BMI, smoking history, clinical stage, estrogen receptor (ER), progesterone receptor (PR), HER2 status, and the first documented serum 25-hydroxyvitamin D (25-(OH)D) level, categorized as <20 deficient, 20-30 suboptimal and >30 optimal. Statistical comparison was performed using Chi-squared tests for categorical variables and Kruskal-Wallis tests for continuous variables. Logistic regression was used to predict the likelihood of vitamin D deficiency. RESULTS: 20,338 BC pts with a documented vitamin D level were identified. Mean age at diagnosis was 58. Using age ≥ 60 as a surrogate for menopausal status, pre- and post-menopausal pts were equally distributed. Stage and hormone receptor status distribution were: 8%, 41%, 32%, 11% and 4% for stage 0, I, II,III and IV, respectively; 63%, 13% and 10% for ER+/HER2 -, HER-2+ and TNBC, respectively. 17.6%, 27.8% and 54.5% of pts had deficient, insufficient and optimal vitamin D levels, respectively. The covariates of age < 60 years (OR 1.24), advanced stage (OR 1.32 for stage II, OR 1.51 for stage III, and OR 1.81 for stage IV), TNBC (OR 1.45), BMI ≥25 (OR 2.02), current smoker (OR 2.11) and lower latitudes (OR 1.36 and 1.19 for central and southern latitude, respectively) were independent predictors of first documented vitamin D deficiency in a multivariate model. CONCLUSION: Vitamin D deficiency may be associated with TNBC and central and southern latitudes. The influences of differential vitamin D supplementation and potential variations in timing of testing warrant further investigation. Citation Format: Joyce G Habib, Janet Espirito, Robyn Harrell, Brian Turnwald, Joyce O'Shaughnessy, Ervin Epstein, Debra Patt. Vitamin D levels, triple-negative breast cancer, and geography: A retrospective analysis of a large database of oncology practices in the United-States (US) [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-09-02.