Effect of implementing population-based prostate-specific antigen screening on testing rates and prostate cancer overdiagnosis in England: a statistical modelling study

Abstract Objective To determine the potential effect of implementing population-based prostate-specific antigen (PSA) screening in England on overdiagnosis and testing rates compared with the current opportunistic testing policy. Design Statistical modeling study. English data on rates of prostate cancer by stage, PSA testing, and life expectancy were merged with epidemiological data on lead time to evaluate plausible overdiagnosis and PSA testing rates from an organized population-based program, in comparison with the current opportunistic policy. In the base-case scenario, organized screening increased the rate of PSA testing in men aged 50 – 69 year and decreased PSA testing in older men. An alternative modeling approach estimated change in overdiagnosis using data from the UK “CAP” trial. Setting England, 2018/19. Participants Adult men. Main outcome measures Rates of PSA testing, early-stage prostate cancer incidence, and overdiagnosis (prostate cancer that would not be diagnosed in a man’s lifetime but for the PSA test). Results In the base scenario, introduction of population-based screening led to an approximate 25% reduction in both PSA testing and overdiagnosis rates in the target population compared with the current policy. This was due to the anticipated decrease in PSA testing and overdiagnosis in men aged 70+ years being larger than the projected increase in PSA testing and overdiagnosis in men 50-69 years. The overall incidence of early-stage cancer prostate cancer was similar. Population-based screening was found to detect more early-stage cancers that were not overdiagnosed, and is therefore likely to have a greater impact on prostate-cancer morbidity and mortality than current policy. Findings were robust in sensitivity analyses including the entirely independent modeling approach based on CAP. Conclusion Opportunistic screening policies in England have led to high rates of overdiagnosis and PSA testing. In comparison with current policy, a risk-adapted, population-based prostate cancer screening program would likely reduce the number of PSA tests and overdiagnoses, and increase benefits of PSA testing from reduced prostate-cancer mortality Population health in England would be improved by either adopting an organized program or by ending PSA testing in primary care. Research in context Evidence before this study It is known that screening for prostate cancer using the PSA test results in considerable overdiagnosis. As a result of these concerns, UK national policy, like most high-income countries, is to have no population-based screening program but to allow men to obtain a PSA test after shared decision-making with a primary care physician. This has led to very high rates of PSA testing among men aged over 70, who experience limited benefit from screening but who are at high risk of overdiagnosis. A small number of studies have modeled the impact of implementing population-based PSA screening but have not incorporated how such a program would affect opportunistic screening in older men. Added value of this study Data on rates of prostate cancer by stage, PSA testing and life expectancy in England were merged with epidemiological data on lead time to model statistical rates of overdiagnosis and PSA testing from an organized population-based program in comparison to current policy. Changes in PSA testing in men above screening age were based on how empirical data on how rates changed in the one country that has implemented population-based screening, Lithuania. We estimate that introduction of population-based screening would reduce both PSA testing and overdiagnosis by about 25%. This is due to the anticipated decrease in PSA testing and overdiagnosis in men aged 70+ years being larger than the projected increase in PSA testing and overdiagnosis in men 50-69 years subject to the population-based screening program. Population-based screening was found to detect more early-stage cancers that were not overdiagnosed and is therefore likely to have a greater impact on prostate-cancer morbidity and mortality than current policy. Findings were robust in sensitivity analyses including an entirely independent modeling approach. Implications of all the available evidence Opportunistic screening policies in England have led to high rates of overdiagnosis and PSA testing. In comparison with current policy, a risk-adapted, population-based prostate cancer screening program would likely reduce the number of PSA tests and overdiagnoses, and increase benefits of PSA testing from reduced prostate-cancer mortality Population health in England would be improved by either adopting an organized PSA screening program or by ending PSA testing in primary care