For a large territorial state like Bavaria only a decentralised cancer registration structure promises successful results: in the form of regional clinical cancer registries and--using the clinical registration as a base--one population-based registry. After ten years of epidemiological cancer registration in Bavaria it can now be shown that the chosen registration concept has proved itself. Currently the completeness of cancer notifications exceeded the international recommended threshold of 90%. A largely complete data stock is available for the years of diagnosis from 2004 to 2005. The task sharing between clinical and population-based cancer registries avoids double registration of data. Both types of registries are supporting physicians and hospitals with a wide palette of services. Together they enable transparency of cancer occurrence as well as transparency of health care for tumour patients.