Men's Osteoporosis Support GroupSerum vitamin D levels and pancreatic cancer risk Am J Epidemiol. 2010 Jul 1;172(1):81-93. Epub 2010 Jun 18. Circulating 25-hydroxyvitamin D and risk of pancreatic cancer: Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Stolzenberg-Solomon RZ and others. PMID: 20562185. Free full-text article is available here. This is a complex pooled nested case-control study ". . . of participants from 8 cohorts within the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers (VDPP) (1974-2006) to evaluate whether prediagnostic circulating 25(OH)D concentrations were associated with the development of pancreatic cancer." It involved 952 incident pancreatic adenocarcinoma cases. The authors' findings and conclusions were, "No significant associations were observed for participants with lower 25(OH)D status. However, a high 25(OH)D concentration (> or =100 nmol/L) was associated with a statistically significant 2-fold increase in pancreatic cancer risk overall (odds ratio = 2.12, 95% confidence interval: 1.23, 3.64). Given this result, recommendations to increase vitamin D concentrations in healthy persons for the prevention of cancer should be carefully considered." Editor's comments. Note that vitamin D is commonly measured in nmol/L or ng/mL. Multiply ng/mL times 2.5 to get nmol/L. In the recent Osteoporosis Issue on vitamin D, you'll note that I found, "From my readings, the normal serum vitamin D should be at least 30 ng/mL (75 nmol/L). I have seen several figures for the normal range extending up to at least 70 ng/mL (175 nmol/L), or higher." Yet in the Stolzenberg-Solomon and others article above, they found more than double the risk of pancreatic cancer in those individuals whose serum vitamin D levels were over 100 nmol/L. This would make one question the goal of getting to 175 nmol/L or higher. The authors point out the previous studies have given conflicting results: some showing increased pancreatic cancer rates with higher serum vitamin D levels, and others showing no increase. In the full-text article they note, "Indeed, a statistically significant 2-fold increased risk of pancreatic cancer was observed among subjects with circulating 25(OH)D concentrations greater than or equal to 100 nmol/L as compared with those with 25(OH)D concentrations of 50–<75 nmol/L. The positive association persisted when each cohort was excluded from the analysis in turn. The association was independent of race/ethnicity, sex, smoking history, obesity, and diabetes. Positive associations were observed in men, women, smokers, never smokers, and nonusers of multivitamin supplements." Thus indicating that the lowest-risk range of serum vitamin D would be in the 50-75 nmol/L range regarding pancreatic cancer. The authors conclude the following in the full-text article: "Before any conclusions regarding vitamin D's potential role(s) in the etiology of pancreatic cancer can be reached, more research is needed, including prospective studies and laboratory investigations of biologically plausible mechanisms that may explain the observations." Thus it appears there is the potential for increased risk of pancreatic cancer with serum vitamin D levels equal to or greater than 100 nmol/L (40 ng/mL). These levels are higher than the recommended lower level of 30 ng/mL (75 nmol/L). So, if you are concerned, discuss this with your care provider and try to keep serum vitamin D levels below 100 nmol/L. Remember that pancreatic cancer, although rare, has a very poor prognosis. I've seen five-year survival rates of 4.5%, so it might be wise to err on the side of caution on this issue.
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