Association between 25-hydroxyvitamin D concentration and breast cancer risk in an Australian population: an observational case–control study

The objective of this study is to examine the association between vitamin D status and risk of breast cancer in an Australian population of women. The study design is observational case–control study, performed at Westmead Breast Cancer Institute, Westmead Hospital, Sydney, Australia. 214 women newly diagnosed with breast cancer were matched to 852 controls, and their blood samples were tested at the same laboratory between August 2008 and July 2010. Circulating 25-hydroxyvitamin D (25(OH)D) concentration, was defined as sufficient (≥75 nmol/L), insufficient (50–74 nmol/L), deficient (25–49 nmol/L) or severely deficient (