NCI collaborates with the University of Oxford in the United Kingdom and scientists from 40 studies worldwide in the Endogenous Hormones, Nutritional Biomarkers and Prostate Cancer Collaborative Group. The group conducts pooled analyses of the relationship between endogenous sex hormones, insulin-like growth factors and subsequent prostate cancer risk. The project has collected data from around 10,000 men with prostate cancer and around 15,000 control men without the disease. First results showed an association between risk of prostate cancer and levels of the growth hormone IGF-1.