[Completeness and quality of baseline data and follow-up in cancer registry--an analysis on the example of colorectal cancer].

BACKGROUND AND AIM: In Germany, data of cancer patients are recorded not only in epidemiological registers but also in clinical cancer registers. To ensure the networking of all included medical partners, quality control, and clinical research it is necessary that cancer cases are captured more or less completely. The aim of the present study was to compare the data sets of two registers.

PATIENTS AND METHODS: Data from patients with colorectal cancer from two large surgical clinics in Magdeburg are recorded in two registers - the Clinical Cancer Registry Magdeburg and the Institute of Quality Assurance in Operative Medicine at the Otto-von-Guericke University Magdeburg. Here we compared the data sets in order to check the completeness of data capturing and to determine factors influencing the degree of completeness.

RESULTS: From all patients captured in the Institute of Quality Assurance, 78.9% are found also in the clinical cancer registry. The percentage improves over the course of time, but also depends on diagnostic criteria such as the staging. There are some differences between both registries, explainable by their specific objectives. Particularly, it is demonstrated that incomplete follow-up record may bias estimates of survival rates from registries.

CONCLUSION: Ensuring the completeness and correctness of data is a major challenge for cancer registries. It has distinct influence on estimated quality parameters such as survival rates.