After differences in implementation and settings were accounted for, two important prostate cancer screening trials provide compatible evidence that screening reduces prostate cancer mortality. These findings suggest that current guidelines recommending against routine prostate-specific antigen (PSA)-based screening may be revised. However, questions remain about how to implement screening so that the benefits outweigh the potential harms of over diagnosis and overtreatment. The findings are published in Annals of Internal Medicine.
Current guidelines from the United States Preventive Services Task Force (USPSTF) recommended against PSA-based screening for prostate cancer since the evidence for the test showed very low probability that it would reduce the prostate cancer mortality. The recommendation was based on outcomes from the PLCO (Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial) and the ERSPC (European Randomized Study of Screening for Prostate Cancer), which provided conflicting outcomes. The ERSPC showed a substantial reduction in deaths from the disease, but the PLCO showed no reduction. However, differences in study implementation, compliance, and practice settings may account for this conflict.
The researchers from the University of Michigan and the National Cancer Institute, tested whether the effects of screening on prostate cancer death differed between the ERSPC and PLCO. The team also estimated the effects of screening in both trials compared with no screening. The scientists used a mathematical model to account for differences in implementation compliance and practice settings and did not found evidence that the effects of screening relative to no screening differed between ERSPC and PLCO. Hence, they concluded that screening could considerably reduce the risk of prostate cancer mortality.
The author of an accompanying editorial from Sloan Kettering Cancer Center said that the current study, rather than focusing on whether PSA screening reduces prostate cancer deaths, should focus on the implementation of prostate cancer screening with PSA so that the benefit outweighs the harms of over diagnosis and overtreatment.