Impact of PSA screening on the incidence of advanced stage prostate cancer in the United States: a surveillance modeling approach.

BACKGROUND: and objective. Both the detection and the treatment of prostate cancer have undergone important clinical advances. Simultaneously, both distant stage incidence and disease-specific mortality have fallen in the United States. A recent study suggests that if prostate-specific antigen (PSA) testing explains the decline in distant stage incidence, then it may be largely responsible for the decline in mortality. The objective was to quantify this link between PSA screening and the decline in distant stage incidence.
METHODS: A fixed-cohort simulation model of prostate cancer progression and screening was adapted to a population-based model that integrates new data on trends in testing and biopsy practices. The model was calibrated to pre-PSA incidence and then screening was superimposed, obtaining incidence projections in the absence and presence of testing. This approach permits calculation of clinically relevant measures for model validation and direct assessment of the role of testing in the distant stage incidence decline.
RESULTS: The model validated well with prior studies of natural history, and the sensitivity analysis indicated that the findings were robust to variation in model parameters. Model results indicate that PSA screening accounts for approximately 80% of the observed decline in distant stage incidence.
CONCLUSIONS: PSA screening contributed to the observed declines in distant stage incidence and mortality in the 1990s. However, additional factors, such as increasing awareness of prostate cancer and advances in treatment, have probably also played a role in these trends.