%0 Journal Article
%T Serum vitamin D levels and survival of patients with colorectal cancer: Post-hoc analysis of a prospective cohort study
%A Hidetoshi Mezawa
%A Tsutomu Sugiura
%A Michiaki Watanabe
%A Chihiro Norizoe
%A Daisuke Takahashi
%A Akira Shimojima
%A Seryna Tamez
%A Yusuke Tsutsumi
%A Katsuhiko Yanaga
%A Mitsuyoshi Urashima
%J BMC Cancer
%D 2010
%I BioMed Central
%R 10.1186/1471-2407-10-347
%X We started a prospective cohort study to find prognostic factors in patients with colorectal cancer from 2003 to 2008 and stored serum samples and clinical data. As part of a post-hoc analysis, serum 25OHD levels were measured by radioimmunoassay. Association between overall survival and serum 25OHD levels were computed using the Cox proportional hazard model adjusted for month of serum sampling as well as age at diagnosis, gender, cancer stage, residual tumor after surgery, time period of surgery, location of tumor, adjuvant chemotherapy and number of lymph nodes with metastasis at surgery. Unadjusted and adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) were determined.Serum 25OHD levels were measured in 257 patients. Only 3% had sufficient levels (30 ng/ml and greater). Based on month of blood sampling, an annual oscillation of 25OHD levels was seen, with levels being lower in spring and higher in late summer. Higher 25OHD levels were associated with better overall survival under multi-variate analysis (HR, 0.91: 95% CI, 0.84 to 0.99, P = 0.027).These results suggest that higher 25OHD levels at surgery may be associated with a better survival rate of patients with colorectal cancer.Sunlight exposure has been suggested to reduce cancer risk [1]. In addition, living at higher latitudes with lower sunlight exposure is positively associated with cancer mortality [2]. Because vitamin D is made under the skin by exposure to ultraviolet-B radiation in sunlight, low levels of serum vitamin D may contribute to a higher risk of morbidity and mortality associated with colon cancer [3]. One plausible explanation for why increased sun exposure and higher circulating levels of vitamin D are associated with a decreased risk of deadly cancers is that epithelial cells convert the primary circulating form of vitamin D, 25-hydroxyvitamin D (25OHD), to its active form, 1,25-dihydoroxyvitamin D, inside the cells; this active form binds to vitamin D receptors in the nu
%U http://www.biomedcentral.com/1471-2407/10/347