How do cancer registries in europe estimate completeness of registration?

Several methods for estimating completeness in cancer registries have been proposed. Little is known about their relative merits. Before embarking on a systematic comparison of methods we wanted to know which indicators were currently in use and whether there had been comparative investigations of estimation methods.

We performed a survey among European cancer registries asking which methods for estimating completeness they used and whether they had performed comparisons of methods.

One hundred and ninety-five European cancer registries were contacted after identification using membership directories of the European Network of Cancer Registries (ENCR) and of the International Association of Cancer Registries (IACR). Fifty-six (29%; 22%-36%) of the 195 cancer registries replied. Forty-eight (86%; 74%-94%) of these stated that they estimated completeness. Thirty-five (73%; 58%-85%) used historic comparisons, 31 (65%; 49%-78%) compared their data with a reference registry, 28 (58%; 43%-72%) registries used mortality incidence ratio. Capture-recapture methods were applied in only 12 (25%; 14%-40%) registries. The flow method was used by ten (21%; 10%-35%) registries. There were regional differences in the use of methods. Comparisons of methods were rare and usually restricted to real data at hand. A systematic comparison including all indicators actually in use in cancer registries was not reported.

A comparison of methods under well defined realistic conditions seems to be indicated. Unifying the methods for estimating completeness would improve validity of comparisons between cancer registries.