In addition to incidence figures, population-based cancer registries that conduct adequate follow-up of their patients are able to estimate the preva- lence of cancer. Prevalence figures give an indication of the burden of the dis- ease in the community. Cancer registries generally assume that once diag- nosed with cancer, an individual remains a prevalent case until death. Thus, prevalence may be estimated from data on incidence and survival. When a registry has been in operation for many years, so that all patients diagnosed with cancer before the establishment of the registry have died, the prevalent cases may simply be enumerated from the registry file, provided, of course, that the.
