Invasive Breast Cancer in Malmö 1961-1992. An epidemiological study

Abstract: In the present thesis incidence, survival, mortality, cure and prognosis in invasive breast cancer in Malmö was studied over a 30 year period. Validated data from the Cancer Registry and the Cause of Death Registry were used. In the process of validation systematical biases were identified in both registers. The incidence increased over time and was strongly related to increases in diagnostic activity, especially mammographic screening. Therefore, comparisons of incidence between populations with differing diagnostic activity is of little informative value. There was a statistically significant decrease of 43% (95% CI:26%-56%) in breast cancer specific mortality 1976-1992. In the remainder of Sweden the decrease for that period was 12% (95% CI: 8%-16%). The decrease was achieved by a comprehensive team effort in breast cancer management. It seems that mammographic screening and medical adjuvant treatment both contributed to the decrease and that these two modalities may act in a synergistic way. Breast cancer specific survival increased significantly in the mid-1970s coinciding with the introduction of mammographic screening and medical adjuvant treatment. Survival is an important variable to predict outcome in the individual case provided the data used are relevant to the prevailing diagnostic and therapeutic conditions. A substantial proportion of operable cases experienced not only clinical but true cure. The number of cured cases increased after 1976. We even identified cases experiencing cure after treatment for distant metastatic disease. In a multivariate model including axillary nodal status and tumour size we found that the Linell-Ljungberg histological classification provides significant prognostic information.