Completeness of case ascertainment at the Irish National Cancer Registry

Cancer registries play a major role in cancer control, including quantifying the burden of cancer in the population, informing health service planning, and evaluating service provision. Registries must achieve a high level of completeness of case ascertainment.

Completeness of case ascertainment for the National Cancer Registry (NCR) in Ireland was estimated.

For all invasive cancers, and the four most common sites, we used two quantitative methods which use information from death certificates to obtain estimates of completeness of registration-the Lincoln-Petersen (LP) estimator (which provides a lower bound estimate) and the flow method (which estimates completeness at a fixed time-point, in this case 5 years). Data were extracted at the end of 2010. Independent case ascertainment was used to assess completeness of breast cancer registration in the 50-64 age group and of rectal cancer in surgical patients diagnosed in 2007.

Completeness of case ascertainment was >99 % for the breast screening age-group and for surgical rectal cancer cases. A lower bound on completeness of case ascertainment for all invasive cancers excluding non-melanoma skin cancers is 94.3 % using the LP estimator. The estimate from the flow method is 97 % after 5 years, [95 % confidence interval (96.2 %, 97.7 %)]. Five-year levels of completeness for the four commonest cancers using the flow method were: colorectal, 97.4 %; lung, 98.7 %; prostate, 95.8 % and breast, 98.0 %.

The estimated levels of completeness for the NCR are satisfactory. Further work is required to compare the methods used.