Overview of the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers

Abstract

The Cohort Consortium Vitamin D Pooling Project of Rarer Cancers (VDPP) brought together 10 cohorts to conduct a prospective study of the association between vitamin D status, measured as serum concentrations of 25-hydroxyvitamin D (25(OH)D), and the development of 7 rarer cancer sites: endometrial, esophageal, gastric, kidney, non-Hodgkin lymphoma, ovarian, and pancreatic cancers. The cohorts come from 3 continents, with participants from a wide range of latitude who are racially diverse. Across each cancer site, there was no evidence of a protective association between higher concentrations of 25-hydroxyvitamin D (>75 nmol/L) and cancer outcome. An increased risk at very high levels (> or =100 nmol/L) was noted for pancreatic cancer, confirming previous reports. The articles included in this issue detail the overall design and governance of the project, correlates of vitamin D status, and results from the cancer site-specific investigations. The Vitamin D Pooling Project realizes a major goal of consortium efforts, namely, to rigorously test hypotheses for rarer cancer outcomes that may not be adequately addressed in any one prospective cohort study. The results of this study have application for the planning and conduct of intervention trials, especially in determining potential risks.

Figure 1.

Odds ratios and 95% confidence intervals for cancer risk by site across categories of circulating levels of 25-hydroxyvitamin D (nmol/L), Cohort Consortium Vitamin D Pooling Project of Rarer Cancers. Odds ratios were derived from conditional logistic regression models. Reference category: 50–<75 nmol/L 25(OH)D. A, kidney cancer adjusted for education, body mass index, height, smoking status at blood draw, history of high blood pressure at blood draw, history of diabetes at blood draw, and alcohol use at blood draw. B, non-Hodgkin lymphoma adjusted for height (≤165, >165–171, >171–177.781, >177.781 cm). C, upper gastrointestinal (combined esophageal and gastric) cancers adjusted for alcohol, smoking, education, and history of gastric surgery. D, pancreatic cancer adjusted for body mass index (<18.5, 18.5–<25.0, 25.0–<30.0, 30.0–<35.0, ≥35.0 kg/m² (WHO categories), missing), smoking (never, former quit ≥15 years ago, former quit 1–<15 years ago, former quit <1 year or currently smoking <20 cigarettes per day, and former quit <1 year or currently smoking ≥20 cigarettes per day), and diabetes (yes, no, missing). The highest category of vitamin D and association with pancreatic cancer is statistically significant (95% confidence interval: 1.23, 3.64). E, endometrial cancer adjusted for education (less than high school, completed high school, vocational school, some college, college graduate, graduate studies, missing), menopausal status (pre-, peri-, post-, missing), age at menarche (<13, ≥13 years of age, missing), parity (0, 1, 2, 3, ≥4, missing), oral contraceptive use (never, ever, missing), hormone replacement therapy (never, ever, missing), smoking (never, former, current, missing), history of high blood pressure (yes, no, missing), history of diabetes (yes, no, missing), and body mass index (<25, 25–<30, ≥30 kg/m², missing). F, ovarian cancer adjusted for duration of oral contraceptive use and number of pregnancies. CI, confidence interval; 25(OH)D, 25-hydroxyvitamin D; WHO, World Health Organization.