Low pretreatment serum concentration of vitamin D at breast cancer diagnosis in postmenopausal women.

Objective: The aim of the study was to evaluate the rate of and risk factors for low pretreatment vitamin D (VitD) levels in postmenopausal breast cancer (BC) women, compared with postmenopausal women without BC.

Methods: A cross-sectional clinical study was conducted to compare 209 women with BC (case group) to 418 women without BC (control group), age range: 45 to 75 years. The case group consisted of women diagnosed with BC, amenorrhea ≥12 months, aged ≥45 years, without use of medication or clinical conditions that might interfere with VitD levels.