An application of the two-source capture-recapture method to estimate the completeness of the Tuscany Cancer Registry, Italy.

The purpose of this study was to apply a two-way capture-recapture method to estimate the Tuscany Cancer Registry completeness, taking into account the presence of dependence between sources. Cases incident during 1995-1996 were flagged according to three sources of information: clinical notes, pathological reports and death certificates. For each group of cases notified by one source the dependence between the other two has been quantified and the completeness has been estimated by a two-way capture-recapture method. When only two (or substantially two) sources are dependent on each other it is possible to correct for it by pooling the two sources in a single group and comparing it with the remainder source by a two-way capture-recapture method. The capture-recapture method has been applied to the overall 12 387 incident cases and to 1569 female breast and 1443 lung cancer cases. After correction for the greatest dependence among the three couples of sources of information, the estimates of completeness were 97.4% for the whole case series, 88.7% for female breast and 99.6% for lung cancer. With the limit of multiple strong dependence between sources, the two-way capture-recapture method seems a simple and useful tool for estimating the completeness of cancer registration.