Changes in use of breast-conserving therapy in years 1978-2000.

The treatment of breast cancer patients has changed rapidly in the past decade, but empirical data at local and national level are scarce. Predicting the consequences of screening for primary treatment is consequently difficult. The aim of this analysis of records on admissions to hospital of women with breast cancer and/or for breast surgery (1975-90) together with a survey of all Dutch radiotherapy departments (1986-88) is to show the change in breast-conserving therapy and other primary treatment before the start of breast cancer screening in The Netherlands. There was a modest increase in breast-conserving therapy after 1981, coinciding with the first publication on its trial, followed by a sharp increase between 1985 and 1990, after the second publication. At the end of that 5 year period, 36% of all women with newly diagnosed invasive breast cancer underwent this type of surgery. Breast-conserving surgery is always followed by radiotherapy, but there has been a clear reduction in post-operative radiation after mastectomy. The percentage of breast-conserving therapy is at present higher in The Netherlands than in the USA. Implementing the Dutch screening programme will result in a maximum increase in breast-conserving therapy at national level of 34%, which stabilises at +21%, or a 50% maximum increase at local level. The number of women treated by mastectomy will ultimately decrease by 9%. Given the rapidity of change towards the use of breast-conserving surgery, which is enhanced by screening, recent information will be needed in predicting capacity and assessing whether screen-detected women are treated adequately.