Independent and joint effects of serum 25-hydroxivitamin D and calcium on breast cancer ratio in an Iran population: A cross-sectional study

BACKGROUND: It has been suggested that Vitamin D and calcium have protective effects against breast cancer. The results about breast cancer and serum Vitamin D and calcium levels are still controversial, indefinite, and insufficient to determine the amount of nutritional needs. Thus, we investigated the association between serum 25-hydroxyvitamin D(25-OH-D) and calcium on the ratio of breast cancer at diagnosis time. MATERIALS AND METHODS: We carried out a hospital-based cross-sectional study in a population of Iran. It comprised 57 breast cancer cases, who were newly diagnosed, and 85 controls in 2013. The serum 25-OH-D and calcium levels were measured. RESULTS: There was not any significant association between 25-OH-D and breast cancer ratio. Odds ratio (OR) comparing the highest quartile to the lowest quartile was 1.03(95% confidence interval[CI] 0.33–3.22, P-trend 0.95). Having sufficient (>75 nmol/L) serum 25-OH-D levels compared to insufficient serum 25-OH-D levels was not associated with a significantly decreased ratio of breast cancer (OR 0.55, 95% CI 0.23–1.29, P = 0.17). Furthermore, an association between calcium and breast cancer did not get statistical significance (OR 0.51, 95% CI 0.17–1.49, P-trend 0.31). The joint effect was negative interaction. CONCLUSION: Vitamin D and calcium do not act on decreasing ratio of breast cancer. Decreasing ratio of breast cancer in relation to serum calcium and Vitamin D level at diagnosis time needs more assessments.