Trends in cancer incidence, survival and mortality in northern Sweden 1960-1986.

The impact of cancer on a population may be measured in several ways. Incidence, relative survival and mortality are frequently utilized for this purpose. Incidence and relative survival are, however, often influenced by changes in the diagnostics of incident cancer, particularly by an altered rate of detection of non-fatal cancer. Mortality, as traditionally studied, is often influenced by changes of death causes diagnostics or of coding routines. In an attempt to overcome some of these difficulties, the concept of excess mortality was suggested, which is independent of death cause diagnoses or coding routines, as well as of the rate of detection of non-fatal cancer. In order to elucidate time trends in the overall effects of cancer we analysed incidence, survival and mortality from all cancer in the northern region of Sweden 1960-1986. An increasing age-adjusted cancer incidence was paralleled by an improvement in relative survival, whereas age-adjusted cancer mortality was mainly unchanged, at least when studied as excess mortality. We interpreted these findings as due mainly to an increased detection of non-fatal cancer, and to an unchanged occurrence rate of fatal cancer.