Completeness of cancer registration in England and Wales: an assessment based on 2,145 patients with Hodgkin's disease independently registered by the British National Lymphoma Investigation.

Records of 2,145 cases of Hodgkin's disease in England and Wales treated by the British National Lymphoma Investigation during 1970-84 were sought in the national and regional cancer registers. One thousand eight hundred and eight-six (88%) were recorded in the national register, either as Hodgkin's disease (86%) or as other or unspecified lymphoma (2%) and 2 (0.1%) were recorded as other cancers. A further 69 (3%) cases were registered by regional cancer registries but had not reached the national register. Adjusting for the distribution of the study cases by region of incidence, we estimate completeness of registration of cases of Hodgkin's disease in the national register at 89.7%, and in the regional registers overall at 92.9%. Completeness did not vary appreciably by age or sex or calendar period. There was however, substantial variation in completeness between regional registries. Estimates were made for all regions except North Western; the lowest estimated completeness were under 90% in Wessex, and the Thames registry regions, and the greatest were 95% or more in Northern, Trent, East Anglia, Oxford, South Western, West Midlands and Mersey. Because these results are confined to one malignancy treated by a particular collaborative network of physicians (although a large and widespread one), and because the patients are restricted to those seen in hospitals, caution must be exercised in extrapolation of the findings to cancer registration generally, but other studies and sources of information lead to similar conclusions about completeness of cancer registration nationally and regionally.