title: Independent and joint effects of serum 25-hydroxivitamin D and calcium on breast cancer ratio in an Iran population: A cross-sectional study.
abstract: 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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of General Surgery and Environmental Health Engineering, Breast Diseases Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Seyed Mostafa
authors.initials: SM
authors.lastname: Shiryazdi
authors.affiliation: Department of General Practitioner, International Campus of Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Ghodratipour
authors.affiliation: Department of General Practitioner, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Seyed Ali
authors.initials: SA
authors.lastname: Shiryazdi
authors.affiliation: Department of General Practitioner, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Sara
authors.initials: S
authors.lastname: Yassini
authors.affiliation: Department of General Surgery and Environmental Health Engineering, Breast Diseases Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Mohaddeseh
authors.initials: M
authors.lastname: Aboueian-Jahromi
authors.affiliation: Department of Biostatics and Epidemiology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Hossien
authors.initials: H
authors.lastname: Fallahzadeh
authors.affiliation: Department of Biostatics and Epidemiology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Farimah
authors.initials: F
authors.lastname: Shamsi
keywords: 25-hydroxyvitamin D; breast cancer; calcium; serum