[Population screening for breast cancer: an interim assessment]

The Dutch national breast cancer programme started in 1989 and ten years later complete coverage of the target population was realised. Screening will save the lives of 27% of all women with screen detected breast cancer. In the other 73% survival will not change, but they will know some years earlier that they have breast cancer. There are 4 lessons from the 12 year experience: (a) mortality reduction due to the present programme can only be identified in individual follow-up data of all women with breast cancer; (b) systematic improvement of the programme's performance can only be based on feedback from a detailed quality and outcome monitoring system; (c) the advice to increase the upper age limit to 75 years was based on the interpretation of trial results for younger age groups and model analysis; (d) breast cancer screening contributed to the systematic improvement of clinical procedures. Current scientific and practical challenges are mortality evaluation, optimising test properties, setting upper and lower age limits, understanding regional differences, developing optimal screening frequencies in women with an elevated breast cancer risk, digital mammography and computer assisted diagnosis.