Circulating 25-Hydroxyvitamin D and the Risk of Rarer Cancers: Design and Methods of the Cohort Consortium Vitamin D Pooling Project of Rarer Cancers

摘要

The Cohort Consortium Vitamin D Pooling Project of Rarer Cancers (VDPP), a consortium of 10 prospectivencohort studies from the United States, Finland, and China, was formed to examine the associations betweenncirculating 25-hydroxyvitamin D (25(OH)D) concentrations and the risk of rarer cancers. Cases (total n ¼ 5,491)nincluded incident primary endometrial (n ¼ 830), kidney (n ¼ 775), ovarian (n ¼ 516), pancreatic (n ¼ 952), andnupper gastrointestinal tract (n ¼ 1,065) cancers and non-Hodgkin lymphoma (n ¼ 1,353) diagnosed in the partici-npating cohorts. At least 1 control was matched to each case on age, date of blood collection (1974–2006), sex, andnrace/ethnicity (n ¼ 6,714). Covariate data were obtained from each cohort in a standardized manner. The majoritynof the serum or plasma samples were assayed in a central laboratory using a direct, competitive chemilumines-ncence immunoassay on the DiaSorin LIAISON platform (DiaSorin, Inc., Stillwater, Minnesota). Masked qualityncontrol samples included serum standards from the US National Institute of Standards and Technology. Condi-ntional logistic regression analyses were conducted using clinically defined cutpoints, with 50–<75 nmol/L as thenreference category. Meta-analyses were also conducted using inverse-variance weights in random-effects models.nThis consortium approach permits estimation of the association between 25(OH)D and several rarer cancers withnhigh accuracy and precision across a wide range of 25(OH)D concentrations.