Correlates of 25-hydroxyvitamin D among Chinese breast cancer patients.

Few studies have investigated vitamin D status in association with modifiable lifestyle factors and clinical characteristics among breast cancer patients, with no studies among Chinese women, who may be at higher risk of vitamin D deficiency. We aimed to evaluate circulating 25-hydroxyvitamin D (25(OH)D) levels in association with clinical and lifestyle factors among 1,940 Chinese breast cancer patients.Participants included breast cancer cases aged 22-77 from a population-based case-control study conducted in Shanghai, China during 1996-1998 (n = 1,044) and 2002-2005 (n = 896). Circulating 25(OH)D levels were measured in plasma samples (95% collected ≤6 months post-diagnosis). Prevalence ORs and 95% CIs were derived from multinomial logistic regression models, adjusting for age, season, and other factors.About 23% and 48% of women were vitamin D deficient (<30 nmol/L) or insufficient (30-50 nmol/L), respectively. Tumor characteristics were not associated with vitamin D status. Higher BMI was associated with increased odds of vitamin D deficiency (ORs (95% CIs): 1 (reference), 1.12 (0.85,1.47), and 1.57 (1.02,2.42), for <23, 23-<27.5, and ≥27.5 kg/m(2), respectively, Ptrend <0.06). Total physical activity was associated with reduced odds of vitamin D deficiency (ORs (95% CIs):1 (reference), 0.84 (0.59,1.20), 0.65 (0.45,0.93), and 0.69 (0.48,1.00), for <7.65, 7.65-<10.6, 10.6-<13.5, ≥13.5 MET-hours/day, respectively, Ptrend