Nation‐wide breast cancer screening in the Netherlands: Support for breast‐cancer mortality reduction

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Abstract
The nationwide 2‐yearly breastcancer screening programme in The Netherlands, for women aged 50‐69, started around 1988, and was predicted to result eventually in a 16% reduction in breastcancer mortality in the total female population. We present the results of screening up to January 1, 1993, and compare these with the predicted results from the costeffectiveness analysis, on which basis this mortality reduction had been calculated. At least 550,000 women aged 50‐69 were invited to screening in 1990‐1992, and 75% of these participated. Cancer was suspected from 5,162 examinations and further investigation was therefore required. Excision biopsy was done in 72% of referrals, and 2,515 breast cancers were detected. The results for 404,000 newly invited women compare favourably with expected values (in parentheses): 78% attendance rate (70%), 1.4% screen positive (1.6%), 6.8 cancers detected per 1,000 women screened (6.4) and 38% of these cancers were DCIS or invasive carcinomas smaller than 11 mm in diameter (36%). More data, e.g., on treatment and interval cancers, will follow in the years to come. These first results can be interpreted as strong early signs of a reduction in breastcancer mortality of at least the predicted size. Screening has sufficiently advanced the diagnosis, as well as or better than expected. Breast cancers diagnosed in this age group without screening are diagnosed at a worse stage than expected. Unfavourable sideeffects, especially falsepositive referrals, might be kept lower than those reported in other countries.