General practitioners and completeness of cancer registry.

STUDY
OBJECTIVE: The aim of the study was to evaluate the role of the general practitioner as a source of information for a cancer registry.
DESIGN: The study involved a random sample of respondents to a letter inviting participation which was sent to all general practitioners in a specific area. Participating doctors were visited to maximise cooperation. Data collection consisted of setting up a retrospective (prevalence) registry of cancer patients diagnosed over a 20 month period, and a prospective (incidence) register over a subsequent 12 month period. The general practitioner cancer file was then linked to the total cancer registry data base to estimate missed cases.
SETTING: The study took place in the catchment area of the Comprehensive Cancer Centre Middle-Netherlands (IKMN). PARTICIPANTS: Of 448 general practitioners in the IKMN region, 152 were willing to participate and of these 52 were randomly selected to take part (11% of all general practitioners in the region).
MEASUREMENTS AND MAIN RESULTS: A total of 1637 tumours were identified from the general practitioners, of which 252 (15.4%) were not included in the cancer registry. Of these, only 22 (1.3%) were not included in the registry because they had tumours diagnosed clinically in outpatients and therefore had been omitted from the usual sources of information available to the cancer registry (pathology reports, hospital discharge letters). The missed cases were mostly older patients with digestive tract tumours.
CONCLUSIONS: On cost-benefit grounds it was not considered feasible to initiate an active cancer registration system among general practitioners, provided that notification of pathological examinations to the registry is complete. Limited under-registration will occur when death certificates cannot be used as an additional source of information.