"Based on these findings, we should refocus our attention on the role of the vitamin D pathway in pancreatic cancer because it may have an impact on the survival of patients," said Federico Innocenti, M.D., Ph.D., associate professor of pharmacy at the University of North Carolina at Chapel Hill Eshelman School of Pharmacy.
In a previous study, Innocenti and his colleagues prospectively collected DNA from 365 patients enrolled in the CALGB 80303 randomized phase III clinical trial testing two treatments for advanced pancreatic cancer. A genome-wide association study (GWAS) was conducted using these DNA samples to identify genetic variations known as single-nucleotide polymorphisms (SNPs) associated with better or worse patient outcome. In the new study, the 300 SNPs previously shown to be most strongly associated with overall survival were tested for their association with overall survival in 408 patients of European descent with advanced pancreatic cancer treated at the Mayo Clinic.
Among the SNPs with concordant effects on overall survival of patients in the CALGB 80303 clinical trial and treated at the Mayo Clinic was a SNP in the gene coding for the vitamin D receptor. This SNP, known as rs2853564 in the VDR gene, was associated with better overall survival.
Patients with two copies of rs2853564 in VDR had a median overall survival of 10.5 months in the Mayo Clinic group and 8.9 months in the CALGB 80303 study. Patients with one copy had a median overall survival of 8.34 months in the Mayo Clinic group and 5.9 months in the CALGB 80303 study. Patients with no copies of the variant allele had a median overall survival of 6.6 months in the Mayo Clinic group and 4.7 months in the CALGB 80303 study.
While Innocenti does not see this study having any immediate clinical implications, he believes it provides more information about the link between vitamin D biology and pancreatic cancer.