Summary

Objectives: 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. 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. Results: 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. Conclusions: 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.