NCI investigators leading prospective cohort studies are part of the international Pooling Project of Prospective Studies of Diet and Cancer, which includes cohorts in Italy, the Netherlands, Canada, Finland, and Sweden. This project is an example of a meta-analysis of individual data as opposed to a meta-analysis of the published literature. The studies in the project were initiated independently and have either completed follow-up of their participants or are ongoing. The pooling of these studies allows far greater statistical power than that permitted by individual studies, provides a wider range of intake for various foods and nutrients, and allows detailed examinations of interactions.