Prospective study of predictors of vitamin D status and survival in patients with colorectal cancer

BACKGROUND: In an earlier study, a 25-hydroxyvitamin D-3 (25(OH) D) score calculated from known predictors of vitamin D status significantly predicted plasma levels of 25(OH) D and the risk of colorectal cancer, but the influence of the 25(OH) D score on survival after diagnosis is unknown. MATERIALS AND METHODS: We prospectively examined the influence of post-diagnosis predicted 25(OH) D levels on mortality among 1017 participants in the Nurses' Health Study and Health Professionals Follow-Up Study who were diagnosed with colorectal cancer from 1986 to 2004. Colorectal cancer-specific and overall mortality according to quintiles of predicted 25(OH) D levels were assessed. Cox proportional hazards models were used to calculate hazard ratios (HRs) adjusted for other risk factors of survival. RESULTS: Higher predicted 25(OH) D levels were associated with a significant reduction in colorectal cancer-specific (P trend = 0.02) and overall mortality (P trend = 0.002). Compared with levels in the lowest quintile, participants with predicted 25(OH) D levels in the highest quintile had an adjusted HR of 0.50 (95% CI, 0.26-0.95) for cancer-specific mortality and 0.62 (95% CI, 0.42-0.93) for overall mortality. CONCLUSION: Higher predicted 25(OH) D levels after a diagnosis of colorectal cancer may be associated with improved survival. Further study of the vitamin D pathway in colorectal cancer is warranted. British Journal of Cancer (2009) 101, 916-923. doi:10.1038/sj.bjc.6605262 www.bjcancer.com Published online 18 August 2009 (C) 2009 Cancer Research UK