Vitamin D and cancer: results from a pooling project
Adequate vitamin D is required for good bone health. In addition, there has been interest in vitamin D as a cancer preventive agent. The prevalence of low levels of vitamin D at a population level has promoted interest in determining the amount of vitamin D required for optimal health.
A series of important articles have recently been published in the July 1 issue of the American Journal of Epidemiology from the Cohort Consortium Vitamin D Pooling Project. The Consortium included 10 cohorts, from three continents (United States, Asia and Europe), to conduct a prospective study of the association between vitamin D status and the development of seven rarer cancers (endometrial, oesophageal, gastric, kidney, non-Hodgkin lymphoma, ovarian and pancreatic). The individual participant data from the 10 cohort studies was analysed as a series of nested case-control studies to test whether prediagnostic circulating 25(OH)D (vitamin D) concentrations were associated with subject risk of the seven cancers. The number of cases of cancer ranges from 516 for ovarian to 1353 for lymphoma.
The Consortium found no benefit from higher concentrations of vitamin D, and no increased risk of cancer from lower concentrations. For pancreatic cancer, a two-fold increased risk was found at very high levels (≥100 nm/L) compared with those with concentrations of 50-<70 nm/L (OR 2.12 (95% CI 1.23-3.64).
The authors call for more research, including prospective studies and laboratory investigations of biologically plausible mechanisms before any conclusions on whether vitamin D affects risk of rarer cancers. They argue against cancer prevention trials with vitamin D supplements as they are unlikely to be large enough or able to detect all adverse events. They also say that the potential benefit of supplementation must far exceed harm before any large-scale trials are carried out.
References:
All articles are free to download [http://aje.oxfordjournals.org/current.dtl]
Helzlsouer KJ et al. Overview of the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol 2010 172: 4-9
Gallicchio L et al. Circulating 25-Hydroxyvitamin D and the Risk of Rarer Cancers: Design and Methods of the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 10-20
McCullough ML et al. Correlates of Circulating 25-Hydroxyvitamin D: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 21-35.
Zeleniuch-Jacquotte A et al. Circulating 25-Hydroxyvitamin D and Risk of Endometrial Cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 36-46.
Gallicchio L et al. Circulating 25-Hydroxyvitamin D and Risk of Endometrial Cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 36-46.
Purdue MP et al. Circulating 25-Hydroxyvitamin D and Risk of Non-Hodgkin Lymphoma: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 58-69.
Zheng W et al. Circulating 25-Hydroxyvitamin D and Risk of Epithelial Ovarian Cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 70-80.
Stolzenberg-Solomon RZ et al. Circulating 25-Hydroxyvitamin D and Risk of Pancreatic Cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 81-93.
Abnet CC et al. Circulating 25-Hydroxyvitamin D and Risk of Esophageal and Gastric Cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Am. J. Epidemiol. 2010 172: 94-106.
