Use of a cancer register for monitoring and evaluating a breast cancer screening programme.

Abstract

To monitor the effectiveness of a breast cancer screening service accurate information is necessary on the incidence of breast cancer before and after screening is introduced. The Wessex Cancer Register has been used to provide data on the incidence prior to screening and arrangements are being made for the exchange of information between the Register and each screening service in Wessex in order that future registrations can be divided into screen-detected and symptomatically-detected cases. Since changes in mortality will not be apparent for some years and are not detectable in small populations, other indicators of effectiveness are required. Stage at presentation predicts mortality; a change in stage distribution as a result of screening would indicate future changes in mortality. The Cancer Register has been used to analyse stage distribution before the advent of screening. Procedures have been adopted for collecting staging data on all breast cancers diagnosed in the future, both within and without the screening service. In this way stage distribution will be compared before and after the implementation of the service and predictions made on the effect on mortality in the future. In addition, information on the incidence of interval cancers will be analysed using the Cancer Register so that, in the long term, an assessment can be made of the appropriate length of the interval between screens. These cancers will be notified to the screening office for review. A Cancer Register can provide the population base from which to measure the true effectiveness of a breast screening service on the community it serves.