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 (