High prevalence of vitamin D deficiency in women with breast cancer: The first Chilean study.

Abstract Background Breast cancer (BC) is the leading cause of female death from malignancy worldwide. One factor that has been associated to a higher incidence and poor prognosis is a Vitamin D deficiency (measured as 25-Hydroxi-Vitamin D (25OHD)). Our aim was to determine 25OHD levels in serum samples of Chilean BC patients before endocrine therapy and its association to clinical parameters at the time of diagnosis. Methods We analyzed clinical records of 105 women, evaluated at the Cancer Center of the Pontificia Universidad Catolica de Chile. Serum levels of 25OHD were determined using a chemiluminescent microparticle immunoassay. Results The prevalence of vitamin D deficiency before endocrine therapy was of 70.5%. Only 7% of our patients showed sufficient vitamin D levels at the beginning of the endocrine treatment. There was a significant correlation found between age and 25OHD levels, and also between body fat percentage and 25OHD levels ( r 2  = 0.04; p  = 0.021; r 2  = 0.028; p  = 0.0432, respectively). Summer 25OHD levels were significantly higher than winter levels ( p  = 0.0322). Conclusion Vitamin D deficiency is highly prevalent in Chilean BC women before endocrine therapy and 25OHD levels are inversely correlated to the age and body fat percentage of patients. Further studies are needed to determine causal relationship between vitamin D levels and BC development and outcome.