Registration of non‐melanoma skin cancers in Scotland—how accurate are site and morphology codes?

Summary Although underreporting; of nun‐melanoma skin cancers to cancer registries is widely acknowledged, less is known about the accuracy of information held about registered cases. In 1993, the accuracy of a random sample of cancer registrations in Scotland attributed to the year 1(W() was assessed by reference to relevant medical records. The sample contained 290 registrations of non‐melanoma skin cancers, 251 (90%) of which had records available for scrutiny. Here we report the results of a detailed analysis of the accuracy of site and morphologv coding of non‐melanoma skin cancers. Following reabstraction of details from available medical records, only three cases (1.2%) did not retain the same first three digit ICD‐9 site code (173. —), although a further three cases were judged to have been registered in error. There were 56 (21.5%) discrepancies in morphology coding, but 21 of these arose through inferences about morphology in the absence of microscopic confirmation, and most of the remainder were of a relatively minor nature. In summary, it does seem possible to collect data about non‐melanoma skin cancers to a reasonably high standard of accuracy. This provides some justification to those who advocate an increased effort directed towards improving levels of completeness of ease ascertainment.