This study aims to determine the population impact of changing strategies for prostate cancer control, by linking trends in disease incidence and mortality with trends in screening and treatment. The advent of PSA screening has transformed the way in which prostate cancer is detected and managed in the US. Today, the majority of prostate cancers in this country are screen-detected and localized. Increasing numbers of newly-diagnosed cases are being treated with hormone suppression therapy (HT), which has traditionally been reserved for advanced tumors. Cause-specific survival among prostate cancer cases has increased dramatically, but the real increase in life expectancy during the PSA era remains unclear. How have advances in screening and treatment contributed to prostate cancer death rates that have fallen by almost 30 percent since the early 1990s? And can racial disparities in patterns of care explain why mortality declines among African Americans are, only two-thirds of those among whites? We will use surveillance modeling to address these questions, building on our previous CISNET work, which modeled PSA screening. Our methods will combine simulation models and maximum likelihood analysis to address the following Specific Aims: (1) Estimate the real improvement in life expectancy among prostate cancer cases during the PSA era; (2) Quantify the contributions to mortality declines of PSA screening and HT, and evaluate whether the benefit of screening given growing use of HT exceeds the benefit that would be expected under standard therapies; (3) Determine whether racial differences in PSA screening and HT can account for the different mortality declines experienced by whites and African Americans;and (4) Address whether disease natural history differs according to race, by estimating lead times associated with PSA screening that are consistent with incidence trends in whites and African Americans. Our models will require reliable estimates of trends in screening and treatment, which we will obtain using SEER-Medicare data, as well as patient claims data from a large HMO based in Northern California. Through this work, our study promises to shed light on two of the most active controversies in prostate cancer research: the value of PSA screening versus advances in prostate cancer treatment, and the link between disparities in care and racial differences in prostate cancer outcomes.
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