Trends in prostate cancer incidence and mortality rates in South Australia, 1979-1993

Objective: To investigate trends in recorded incidence and mortality rates for prostate cancer in South Australia. Design: A multiple Poisson regression analysis of recorded incidence (by diagnostic period) and mortality (by year of death), after adjusting for age at diagnosis and residential location. Subjects and setting: 8073 patients with prostate cancer and 2659 who died of prostate cancer as notified to the South Australian Cancer Registry for 1977-1993. Main outcome measures: The relative risk of a recorded diagnosis of prostate cancer (by period of diagnosis), and of a death from prostate cancer (by year of death). Results: During 1977-1989, the recorded age-standardised incidence of prostate cancer was stable, but it increased markedly thereafter. The relative risk (95% confidence limits) of diagnosed prostate cancer was 1.36 (1.29, 1.43) in 1990-1992, and 2.26 (2.12, 2.42) in 1993, when compared with 1977-1989. There was a smaller and 1988 certain increase in prostate cancer mortality. Conclusions: The large increase in recorded incidence of prostate cancer in South Australia is thought to be due mostly to increased disclosure of latent cases from increased clinical investigations. Until there is experimental evidence of health benefits from screening and related investigations for prostate cancer in asymptomatic men, it will be difficult to reconcile benefits with costs.