Improving the comparability of cancer registry treatment data and proposals for a new national minimum dataset.

Background: There is no consistent or standardized practice for the collection of treatment data in UK cancer registries. This limits the usefulness and effectiveness of undertaking multiregional or national studies of treatment outcomes and survival.

Methods: A working group was established to examine the practices for recording the type and the amount of treatment data held in the cancer records at different registries. A common set of anonymized case notes for breast and colorectal cancer patients, drawn from each registry, was employed to eliminate any selection bias. Each registry coded these case notes according to their own criteria, and the comparability of such data between registries was determined from their returns.

Results: Of the 11 registries in England, seven participated in the full study, with a total of 84 records being submitted by five registries. A flow diagram was constructed to show how specific data items in the cancer record structure could be linked between registries. Errors or inconsistencies in recording treatment details were identified, and the constraints in data comparability were defined from the case note returns.

Conclusion: Variations in coding practice between registries were such as to vitiate interregional or national comparisons of current data. The working group recommended an extended minimum dataset, which included a date for the start of each treatment modality, that most registries should be able to implement with some system changes.