More Evidence to Support PSA Testing: Study Suggests Long-Term Benefits of PSA Screening
A new article used statistical modeling to show that PSA screening may be more beneficial than is generally understood.
Patience is a virtue when waiting for research to reveal the big picture.
The study in the prestigious New England Journal of Medicine, entitled “Reconsidering the Trade-offs of Prostate Cancer Screening,” was led by Jonathan E. Shoag, M.D. and other researchers from Weill Cornell Medicine in New York. They wrote that a current prevailing opinion regarding PSA screening stems from two large, randomized trials that showed little or no benefit to
screening. “This view is problematic,” the authors said.
One of these trials is the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, which had a nearly 90% contamination rate in the control group. This means that 90% of the men in the trial who were not supposed to be screened for prostate cancer had at least one PSA test, which skewed the results against PSA screening. When the U.S. Preventive Services Task Force (USPSTF) published earlier recommendations against PSA screening, they weighed heavily on data from the PLCO trial.
The other trial is the European Randomized Study of Screening for Prostate Cancer (ERSPC), which
also had a cancer screening group and a control group. The latest results from this trial, after 16 years of follow-up, estimated that among men ages 55-69 years old, 570 men would need to be screened with a PSA blood test to prevent one death from prostate cancer. This benefit is similar to recommendations supporting breast cancer screening.
Projecting longer-term benefits
Sixteen years of follow-up shown in the ERSPC trial thus far may not be long enough to fully see the mortality benefit from PSA screening. This is because men often begin screening in their 50s, and the median age at which men die from prostate cancer is 80 years.
The authors used statistical modeling to project estimates of the long-term effects of PSA screening. Their model predicts that 385 men would need to undergo a PSA blood test and 11 additional men would need to be diagnosed with prostate cancer to prevent one prostate cancer death at 25 years in the U.S., suggesting a greater long-term benefit than currently shown in the ERSPC trial.
More than just preventing death
There are benefits to PSA screening beyond just reducing death rates, primarily avoiding metastatic, advanced prostate cancer, which is incurable, can be painful, and has long-term side effects from treatment. Data from the ERSPC and the Prostate Testing for Cancer and Treatment (ProtecT) trial show that screening results in a reduced risk of metastatic disease.
As clinicians who screen, diagnose, and treat patients with prostate cancer and as statisticians who are devoted to understanding the effects of cancer screening, we suggest that the balance of benefits and harms of screening may be more favorable than is generally appreciated.
