The Association between Prognostic Demographic and Tumor Characteristics of Breast Carcinomas with Serum 25-OH Vitamin D Levels

Objective: Epidemiologic studies show that women with low 25-OH vitamin D levels have an increased risk of breast cancer incidence and mortality. However, there is a lack of research examining vitamin D levels and prognostic variables in breast cancer patients. The aim of this study is to identify the associations between 25-OH vitamin D levels, demographic variables, and prognostic pathological and genetic characteristics of breast cancers.

Method: This study cohort consists of 155 women who underwent breast cancer surgery at the University of Rochester between 1/2009 and 9/2010. Vitamin D levels were obtained in the 1-year period before and after surgery (74% of vitamin D levels within 6 months). Prognostic variables included age, race, menopausal status, Oncotype DX score, TNM staging, ER/PR status, and HER2 expression. ANCOVA, linear regression, and logistic regression were used to determine the association between prognostic variables and 25-OH vitamin D levels, while controlling for relevant covariates (age, race, and month of blood draw).

Results: Non-Caucasian (OR = 3.8; P < 0.01) and premenopausal (OR = 3.5; P < 0.01) breast cancer patients were significantly more likely to have suboptimal 25-OH vitamin D levels than Caucasian and postmenopausal patients, respectively. Women with invasive breast tumors were more likely to have suboptimal vitamin D levels (invasive OR = 2.4; P = 0.10) and lower mean 25-OH vitamin D levels (invasive: 30.5 ng/mL vs. in situ: 36.9 ng/mL; P = 0.04). A significant correlation (r = −0.42; P = 0.04) between decreasing vitamin D levels and increasing Oncotype score was noted. Breast cancer patients who had ER- and triple-negative breast tumors were more likely to have suboptimal levels of 25-OH vitamin D (ER-OR = 2.4; P = 0.07; triple-negative OR = 2.6; P = 0.09).

Conclusions: Breast cancer patients with suboptimal vitamin D levels were more likely to have tumors with more aggressive tumor profiles, worse prognostic markers (ER- and triple-negative tumors), and higher recurrence risk (Oncotype scores), lending support to previous research that found decreased breast cancer survival among vitamin D deficient individuals. Further research is needed to elucidate the biological relationship between vitamin D and prognostic breast cancer markers.