The 20th century saw the establishment of the first population-based cancer registries with the purpose of generating data to describe cancer patterns and trends, and with the ultimate goal of guiding national cancer control planning. In recent years, the roles and activities of cancer registries have been steadily expanding. This dissertation argues that these new roles are now becoming as important and valuable to clinicians, policy makers and public health authorities as the traditional ones. For some issues, these new roles played by cancer registries can address knowledge gaps that cannot be assessed or evaluated using other approaches. The dissertation presents ten papers conducted using the data of the Geneva Cancer Registry that explore these new directions. Together these papers present a strong case for ensuring that national and local authorities build on recent experience to systematically invest in and expand the roles and activities of cancer registries.