Marked differences in practice exist between cancer registries, for example, with respect to data sources, definitions and processing methods. To make cancer registry data comparable, which is one of the main aims of the Network, it is important that common rules and definitions are used. Working Groups have been established to examine specific topics, identified as potentially problematic. These expert working groups are constituted of 3-4 people, selected by the ENCR Steering Committee. Their task is to study the problem and make recommendations for the cancer registries. The following topics have already been discussed:

Standard dataset Incidence Date also available in French , German and Spanish Multiple Primaries Bladder Tumours also available in French , German and Spanish Tumours of the Brain and Central Nervous System Leukaemias and Lymphomas Basis of Diagnosis Non-Melanoma Skin Cancers Method of Detection in Relation to Screening Confidentiality in Cancer registration also available in French Condensed TNM for Coding the Extent of Disease also available in French