Regina Ziegler

NCI, DCEG, EBP

PLCO (Learn more about this study)

2007-0019

Apr 6, 2007

Studies of Diet and Pancreatic Cancer with the Diet and Cancer Pooling Project

With the growing number of epidemiologic publications on the relation between dietary factors and cancer risk, pooled analyses that summarize results from multiple studies are becoming more common. In the ongoing Pooling Project of Prospective Studies of Diet and Cancer, begun in 1991, the primary data from prospective cohort studies meeting prespecified inclusion criteria are analyzed using standardized criteria for modeling of exposure, confounding, and outcome variables. In addition to evaluating main exposure-disease associations, analyses are also conducted to evaluate whether exposure-disease associations are modified by other dietary and nondietary factors or vary among population subgroups or particular cancer subtypes. Study-specific relative risks are calculated using the Cox proportional hazards model and then pooled using a random- or mixed-effects model. The study-specific estimates are weighted by the inverse of their variances in forming summary estimates. The Pooling Project of Prospective Studies of Diet and Cancer will begin analyses of diet and pancreatic cancer in the spring of 2007. Little is known about modifiable risk factors for this rapidly fatal cancer. A total of 15 - 20 cohorts, including nearly all of the major cohorts in the world, will provide data. PLCO has been invited to participate. Practically all of these cohorts, including PLCO, have insufficient numbers of pancreatic cancer cases to support robust, accurate, informative analyses of dietary factors and pancreatic cancer. The dietary factors to be studied include anthropometry, fruits and vegetables, carotenoids, grains, dietary fiber, alcohol, meat, and sugar-sweetened beverages. These exposures were chosen on the basis of the limited published literature on the nutritional epidemiology of pancreatic cancer and on the availability of appropriate data from the majority of the cohorts. In addition, broad dietary exposures that have been examined with respect to other cancers were emphasized.