Improvements in survival for women with breast cancer in Scotland between 1987 and 1993: impact of earlier diagnosis and changes in treatment.

We investigated changes in survival, and their causes, in women with early breast cancer diagnosed in Scotland. The Scottish Cancer Registry identified 1617 and 2077 such women, without metastases at diagnosis who underwent surgery as part of their primary treatment, diagnosed in 1987 and 1993, respectively. There was a statistically significant 11% improvement in 8-year survival between 1987 and 1993. Survival improved across almost all clinical/pathological, treatment and health care delivery/deprivation categories; improvement was not limited to those women diagnosed through the screening programme. In a multivariate model, improved survival appeared to be explained largely by screening and clinical/pathological prognostic factors. Deprivation also had an adverse effect on survival; however, the geographical variation in survival observed for women diagnosed in 1987 was not apparent by 1993. We did not demonstrate a significant independent effect of surgical caseload on survival. We conclude that survival has increased partly as a consequence of screening and earlier diagnosis, but also due to improvements in the organisation and delivery of care.