Tsodikov, A., et al, Ann Intern Med 167(7):449, October 3, 2017
BACKGROUND: In 2012 the U.S. Preventive Services Task Force recommended against routine prostate cancer screening because its lack of effect on long-term mortality. Their recommendations (which are being updated) were based mainly on the ERSPC (European Randomized Study of Screening for Prostate Cancer) and PLCO (Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial) trials. However, these two trials are substantially different in terms of design, settings, screening intensity, baseline risk and screening effect on mortality (a relative reduction of 21% vs. no reduction, respectively).
METHODS: To evaluate whether the mortality difference persisted after accounting for implementation and practice setting differences, these multinational authors combined data from both trials to conduct a traditional statistical analysis that adjusted for participant age and trial setting, and extended analyses that overcame variability in screening intensity by considering mean lead times, which indicated increased prostate cancer incidence and earlier diagnosis with vs. without screening. Follow-up was restricted to eleven years for both trials.
RESULTS: The traditional analysis demonstrated a marginally different screening effect on mortality between trials (p=0.087), and an overall relative risk reduction of 16% (p=0.010). Extended analyses indicated no difference in screening effect on mortality between trials (p=0.37 to 0.47), and an overall association of longer mean lead times with a lower risk of prostate cancer specific death (p=0.0027 to 0.0032). Screening was estimated to lead to a 25-31% and a 27-32% relative reduction in risk of prostate cancer death in the two trials, respectively, vs. no screening (NNT = ~ 1,111 for 11 years of regular screening).
CONCLUSIONS: This analysis of data from two large prostate cancer-screening trials found that screening significantly reduced prostate cancer mortality risk compared with no screening. 18 references ( [email protected] for reprints)