Pretreatment Serum Concentration of Vitamin D and Breast Cancer Characteristics: A Prospective Observational Mediterranean Study

BACKGROUND: Recent studies of the correlation between breast cancer (BC) and vitamin D yielded contrasting results. Although preclinical and clinical evidence has implicated vitamin D in BC prevention and outcome, little is known about the link between vitamin D and specific BC histologically defined subtypes. In the attempt to clarify this association we correlated vitamin D levels with BC characteristics. PATIENTS AND METHODS: We enrolled 220 pre- and postmenopausal women with early BC in this prospective observational trial. Data on the patients' clinical and specific BC pathological characteristics were collected and related to vitamin D levels, stratified in deficient (< 20 ng/mL), insufficient (20-30 ng/mL), and sufficient (> 30 ng/mL). BC subtypes were defined according to the 14th St Gallen Breast Cancer Conference. RESULTS: Deficient vitamin D levels were correlated with Grade 3 (P = .015) and node-positive (P = .043) BC, and with a higher body mass index (P = .017). Insufficient vitamin D levels were associated with estrogen receptor expression in the primary tumor (P = .033). Vitamin D levels were unrelated to the histological molecular subtypes of BC. CONCLUSION: Deficient vitamin D levels were correlated with more aggressive disease, namely, node-positive high grade BC, and with obesity. Should our findings be confirmed in larger prospective studies, nutritional programs designed to reduce body weight, and vitamin D supplementation might be considered a BC prevention strategy.