EVALUATION OF THE EFFECT OF BREAST-CANCER SCREENING BY RECORD LINKAGEWITH THE CANCER REGISTRY, THE NETHERLANDS

Objective-To evaluate the effect of a breast cancer screening programm e by record linkage with the cancer registry. Setting-Breast cancer sc reening programme in mid- and southern Limburg, the Netherlands. Metho d-The data files of the breast cancer screening programme and the Maas tricht Cancer Registry were linked in order to evaluate the effect of breast cancer screening. Only the first primary breast tumour was incl uded in the evaluation. Results-From 1990 until 1995 90001 women parti cipated in the first round of the breast cancer screening programme an d 64 637 in subsequent rounds. After the introduction of screening the annual number of breast cancer diagnoses increased by almost 50%. The incidence decreased to previous levels after completion of the first screening round. Record linkage detected 219 interval cancers (within two and a half years of a screening), a proportionate incidence of 31% in the first year and 60% in the second year of the two-year interval between screenings. The incidence of node positive breast cancer was 1% lower in 1994 and 15% lower 1995 than the incidence in the period 1 987-90. Conclusions-Evaluation of the effect of breast cancer screenin g in the Netherlands can be performed using routinely available cancer registry data. The results of this evaluation seem promising, but fur ther studies are necessary to find ways to reduce the incidence of int erval cancer.