In recent years, plasma 25-hydroxyvitamin-D (vitamin D) levels have been implicated in the pathogenesis of pancreatic cancer, and several teams of investigators have attempted to clarify this association to determine whether vitamin D measurements have a prognostic role as a biomarker in this disease setting.1,3-5
For example, a post hoc analysis of the randomized phase 3 MPACT trial (NCT00844649) found no association between vitamin D levels and overall survival (OS) in patients with pancreatic cancer.1 The MPACT study authors compared nab-paclitaxel and gemcitabine with gemcitabine alone in 861 patients with metastatic pancreatic cancer.2 Data on vitamin D levels were available for 422 of the patients, who were subsequently divided into 3 groups based on vitamin D level classification: sufficient (> 30 ng/mL), relatively insufficient (20-30 ng/mL), and insufficient (<20 ng/mL).
Von Hoff et al did not note any statistically significant differences in the median OS between the 3 groups.1 The median OS was 7.9 months in the insufficient group, 9.4 months in the relatively insufficient group, and 7.8 months in the sufficient group. No significant differences in the median OS in relation to vitamin D levels were seen in intergroup analyses, either. Although the study authors concluded that there was no association between vitamin D level and OS, they noted that the lack of extensive samples and the extent of disease could have influenced these findings.
Authors of a meta-analysis that included 12 studies that evaluated the impact of vitamin D levels on pancreatic cancer risk and mortality also found no statistical difference in survival outcomes.3 In this evaluation, elevated levels of vitamin D were found to correlate with lower pancreatic cancer mortality without significant heterogeneity (HR, 0.81; 95% CI, 0.68-0.96). Data on progression-free survival were limited, but also suggested no association between vitamin D levels and this outcome.
Notably, elevated 25 vitamin D levels did not reduce the risk for pancreatic cancer (relative risk [RR], 1.02; 95% CI, 0.66-1.57), and vitamin D intake did not correlate with the risk for pancreatic cancer development (RR, 1.11; 95% CI, 0.67-1.86).
Daily vitamin D intake and pancreatic cancer riskwas also the focus of a pooled data analysis involving results from 9 case control studies from the International Pancreatic Cancer Case-Control Consortium. By contrast with the findings from the meta-analysis, data from this pooled analysis demonstrated a link between higher amounts of vitamin D intake—with the threshold between “low” and “high” defined as 100 international units (IU)/day—and increased risk for pancreatic cancer (overall risk, 1.13; 95% CI, 1.07-1.19).4 No significant impact was observed when the results were adjusted for cigarette smoking. The study authors noted that the association between vitamin D intake and pancreatic cancer could be associated with low vitamin A intake.