Higher vitamin D levels associated with lower risk of deadly cancer
Tuesday, November 29, 2011. In an article appearing online on November 15, 2011 in the journal Cancer Epidemiology, Biomarkers & Prevention, Brian M. Wolpin of Dana-Farber Cancer Institute and his colleagues report an association between higher circulating levels of vitamin D and a lower risk of pancreatic cancer among participants in five large prospective studies.
The current study included 451 subjects diagnosed with pancreatic cancer matched with two to three cancer-free controls, selected from participants in the Health Professionals Follow-Up Study, the Nurses' Health Study, the Physicians' Health Study, the Women's Health Initiative-Observational Study and the Women's Health Study. Average follow-up periods ranged from 14.1 to 25.3 years. Stored plasma samples collected upon enrollment in the studies were analyzed for 25-hydroxyvitamin D.
Vitamin D levels averaged 61.3 nanomoles per liter among participants diagnosed with pancreatic cancer and 64.5 nanomoles per liter in the control subjects. A declining risk of the disease was observed in association with rising levels of vitamin D. When participants whose vitamin D level was among the top one-fifth of subjects were compared with those in the lowest fifth, a 33 percent reduction in pancreatic cancer risk was observed. Adjustment for age and separate analysis of subgroups, including Caucasians, men, and women, resulted in a similar association.
When the risk of cancer of the pancreas was analyzed according to sufficient or insufficient vitamin D status, compared to those with insufficiency (defined as less than 50 nanomoles per liter) there was a 29 percent lower risk determined for those with sufficient levels of 75 nanomoles per liter or higher. In contrast with findings suggested by an earlier study, no increased risk was observed among men and women whose vitamin D levels were 100 nanomoles per liter or greater.
"Vitamin D and its analogues can slow proliferation of pancreatic cancer cells both in cell culture and in xenograft mouse models," the authors write. "Clinical studies are underway to exploit these effects of vitamin D and its analogues in patients with pancreatic cancer."
"In light of the high prevalence of vitamin D insufficiency in the population, further studies should examine whether increasing vitamin D levels impacts the incidence of this highly lethal malignancy," they conclude.