Cancer registries are unique in being able to provide population-based data to monitor geographic variation and changes in cancer risk or survival over long periods of time. Historically, the role of cancer registries has been to collect population-based data on all cancers being diagnosed, treated or dead within a well-defined population. In recent years the work of all registries has expanded to include the analysis of aspects of cancer prevention, treatment and care. Registries can assess how local and national targets for cancer services provision are met, and can contribute important information to the planning of services. Cancer registration is not an end in itself. Its tasks are closely linked to the scientific research and practical fight against cancer diseases and are adapted in parallel.