As of July 1, 2005 it is obligatory to report new cases of any malignant disease in the state of North Rhine-Westphalia to the Epidemiologcal Cancer Regsitry (EKR NRW). Approximately 100,000 new cases of malignant diseases are reported every year.The aims of the collaboration are: analyses of time trends of incidence and mortality of cancer; linkage of cancer registry data with external cohort studies using stochastic record linkage procedures; introduction of new types of association analyses using geo-informatics; contributions to the evaluation of early detection and screening programs for cancer.