Quality of cancer registry data: completeness of TNM staging and potential implications

Population-based cancer registries play a key role in cancer monitoring, and their utility relies heavily on the completeness and validity of the registered data. It is crucial to reduce incomplete stage information and to strengthen the role of TNM stage as key variables in the Danish Cancer Registry and other cancer registries. In this respect, distinction in cancer registries between evidence that staging was not performed clinically versus truly missing data would be an important next step. The present studies examined the completeness of the TNM staging data. In future studies it will be important to evaluate the accuracy as well.