Circulating Vitamin D and Colorectal Cancer Risk: An International Pooling Project of 17 Cohorts.
- Behavioral and Epidemiology Research Program, American Cancer Society, Atlanta, GA.
- Departments of Epidemiology.
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD.
- Department of Epidemiology, Rollins School of Public Health, Winship Cancer Institute, Emory University, Atlanta, GA.
- Division of Epidemiology, Department of Population Health and Perlmutter Cancer Center.
- Epidemiology and Prevention Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy.
- Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA.
- Division of Epidemiology and Biostatistics, Department of Population Health, New York University School of Medicine, New York, NY.
- Department of Preventive Medicine, Keck School of Medicine and Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA.
- Department of Occupational Medicine, Epidemiology and Prevention, Feinstein Institute for Medical Research, Hofstra Northwell School of Medicine, Great Neck, NY.
- Heartland Assays, LLC, Ames, IA.
- Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA.
- Section of Nutrition and Metabolism, International Agency for Research on Cancer (IARC-WHO), Lyon, France.
- Division of Genetics and Epidemiology.
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
- Department of Food and Nutrition, Seoul National University, Seoul, Korea.
- Department of Health National Institute for Health and Welfare, Helsinki, Finland.
- Epidemiology Program, University of Hawaii Cancer Center, Honolulu, HI.
- Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI.
- Department of Epidemiology and Biostatistics, The School of Public Health, Imperial College London, London, UK.
- Cancer Registry of Norway, Institute of Population-Based Cancer Research, Oslo, Norway.
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY.
- Epidemiology and Prevention Group, Center for Public Health Sciences, National Cancer Center, Tokyo, Japan.
- Department of Health Promotion Sciences, University of Arizona Mel and Enid Zuckerman College of Public Health, Tucson, AZ.
- Channing Division of Network Medicine.
BACKGROUND: Experimental and epidemiological studies suggest a protective role for vitamin D in colorectal carcinogenesis, but evidence is inconclusive. Circulating 25-hydroxyvitamin D (25(OH)D) concentrations that minimize risk are unknown. Current Institute of Medicine (IOM) vitamin D guidance is based solely on bone health.
METHODS: We pooled participant-level data from 17 cohorts, comprising 5706 colorectal cancer case participants and 7107 control participants with a wide range of circulating 25(OH)D concentrations. For 30.1% of participants, 25(OH)D was newly measured. Previously measured 25(OH)D was calibrated to the same assay to permit estimating risk by absolute concentrations. Study-specific relative risks (RRs) for prediagnostic season-standardized 25(OH)D concentrations were calculated using conditional logistic regression and pooled using random effects models.
RESULTS: Compared with the lower range of sufficiency for bone health (50-<62.5 nmol/L), deficient 25(OH)D (<30 nmol/L) was associated with 31% higher colorectal cancer risk (RR = 1.31, 95% confidence interval [CI] = 1.05 to 1.62); 25(OH)D above sufficiency (75-<87.5 and 87.5-<100 nmol/L) was associated with 19% (RR = 0.81, 95% CI = 0.67 to 0.99) and 27% (RR = 0.73, 95% CI = 0.59 to 0.91) lower risk, respectively. At 25(OH)D of 100 nmol/L or greater, risk did not continue to decline and was not statistically significantly reduced (RR = 0.91, 95% CI = 0.67 to 1.24, 3.5% of control participants). Associations were minimally affected when adjusting for body mass index, physical activity, or other risk factors. For each 25 nmol/L increment in circulating 25(OH)D, colorectal cancer risk was 19% lower in women (RR = 0.81, 95% CI = 0.75 to 0.87) and 7% lower in men (RR = 0.93, 95% CI = 0.86 to 1.00) (two-sided Pheterogeneity by sex = .008). Associations were inverse in all subgroups, including colorectal subsite, geographic region, and season of blood collection.
CONCLUSIONS: Higher circulating 25(OH)D was related to a statistically significant, substantially lower colorectal cancer risk in women and non-statistically significant lower risk in men. Optimal 25(OH)D concentrations for colorectal cancer risk reduction, 75-100 nmol/L, appear higher than current IOM recommendations.