Vitamin D and pancreatic cancer: a pooled analysis from the Pancreatic Cancer Case-Control Consortium

Abstract

Background: The potential role of vitamin D in the aetiology of pancreatic cancer is unclear, with recent studies suggesting both positive and negative associations.

Patients and methods: We used data from nine case-control studies from the International Pancreatic Cancer Case-Control Consortium (PanC4) to examine associations between pancreatic cancer risk and dietary vitamin D intake. Study-specific odds ratios (ORs) were estimated using multivariable logistic regression, and ORs were then pooled using a random-effects model. From a subset of four studies, we also calculated pooled estimates of association for supplementary and total vitamin D intake.

Results: Risk of pancreatic cancer increased with dietary intake of vitamin D [per 100 international units (IU)/day: OR = 1.13, 95% confidence interval (CI) 1.07-1.19, P = 7.4 × 10(-6), P-heterogeneity = 0.52; ≥230 versus <110 IU/day: OR = 1.31, 95% CI 1.10-1.55, P = 2.4 × 10(-3), P-heterogeneity = 0.81], with the association possibly stronger in people with low retinol/vitamin A intake.

Conclusion: Increased risk of pancreatic cancer was observed with higher levels of dietary vitamin D intake. Additional studies are required to determine whether or not our finding has a causal basis.

Keywords: case–control studies; pancreatic cancer; pooled analysis; vitamin D.

Figure 1.

Study-specific^a and pooled odds ratios (ORs)^b for pancreatic cancer for an increase in dietary vitamin D intake^c of 100 IU/day: fully adjusted estimates. ^aStudy-specific ORs calculated using unconditional logistic regression adjusted for the confounders in supplementary Table S2, available at Annals of Oncology online. Dietary vitamin D intake included in models as a continuous exposure. ^bPooled OR calculated using a random-effects model. ^cDietary vitamin D intake was energy-adjusted by the residuals method for all studies except Ontario. ^dNumber of cases (Ca) and controls (Co) used to produce fully adjusted estimates. Differences with numbers given in Table 2 are due to missing confounder data. CI, confidence interval; QPCS, Queensland Pancreatic Cancer Study; UM, University of Minnesota; SEARCH, Surveillance of Environmental Aspects Related to Cancer in Humans; UCSF, University of California, San Francisco.