NATIONWIDE BREAST-CANCER SCREENING IN THE NETHERLANDS - RESULTS OF INITIAL AND SUBSEQUENT SCREENING 1990-1995

Based on an extensive cost-effectiveness analysis, the Dutch nation-wi de breast cancer screening programme started in 1990, providing a bien nial screen examination to women aged 50 to 69 years. The programme is monitored by the National Evaluation Team, which annually collects ta bulated regional evaluation data to determine performance indicators. This study presents (trends in) the outcomes of initial and subsequent screening rounds, 1990-1995, and compares them to the predictions of the cost-effectiveness-analysis. Up to 1996, 88% of the target populat ion was covered by the programme and more than 2.4 x 10(6) women were invited. The overall attendance rate was 77.5% with little differences between screening rounds and age groups; the highest rate was found i n non-urbanised areas (82.4%). Of 1,000 initially (and 2 years thereaf ter) screened women, 13.4 (6.6) were referred for further investigatio n, 9.7 (4.4) were biopsied and 6.4 (3.4) had breast cancer. The positi ve predictive values of screen test and biopsy were 47% (51%) and 66% (78%), respectively. DCIS was diagnosed in 0.9 (0.5) and invasive canc ers less than or equal to 10 mm in 1.5 (1.0) per 1,000 screens. Lymph node metastases were found in 28% (24%) of the invasive cancers. Excep t the increasing attendance, which was much higher than expected, the results were fairly constant over the years. Contrary to initial scree ns, the results of subsequent screens did not fulfil expectations with regard to breast cancer detection and tumour size distribution. We co nclude that the nation-wide screening programme is being implemented s uccessfully. Given the results, the programme should contribute to a s ubstantial breast cancer mortality reduction in the future. The discre pancy between observed and expected results in subsequent screens has to be watched carefully. (C) 1998 Wiley-Liss, Inc.