Abstract
BACKGROUND: Studies show that women with low vitamin D levels have an increased risk of breast cancer (BC) incidence and mortality, but there is a lack of research examining vitamin D levels and prognostic variables in BC patients. The aim of this study is to examine 25-OH vitamin D levels between BC cases and controls and by prognostic indicators among BC cases. METHODS: 25-OH vitamin D levels were collected from 194 women who underwent BC surgery and 194 cancer-free (CF) controls at the University of Rochester between January 2009 and October 2010. Mean 25-OH vitamin D levels and odds ratios (OR) were calculated by case/control status for the overall cohort and by prognostic indicators (invasiveness, ER status, triple-negative status, Oncotype DX score, molecular phenotype) for BC cases. RESULTS: BC cases had significantly lower 25-OH vitamin D levels than CF controls (BC: 32.7 ng/mL vs. CF: 37.4 ng/mL; P = .02). In case-series analyses, women with suboptimal 25-OH vitamin D concentrations (<32 ng/mL) had significantly higher odds of having ER- (OR = 2.59, 95% confidence interval [95% CI] = 1.08-6.23) and triple-negative cancer (OR = 3.15, 95% CI = 1.05-9.49) than those with optimal 25-OH D concentrations. Women with basal-like phenotype had lower 25-OH vitamin D levels than women luminal A phenotype (basal-like: 24.2 ng/mL vs. luminal A: 32.8 ng/mL; P = 0.04). CONCLUSIONS: BC patients with a more aggressive molecular phenotype (basal-like) and worse prognostic indicators (ER- and triple-negative) had lower mean 25-OH vitamin D levels. Further research is needed to elucidate the biological relationship between vitamin D and BC progression.