Study: Side Effects Outweigh Prostate Cancer Screening Benefits

A large European study found that PSA screening reduces prostate cancer deaths, but that these benefits do not outweigh the harms of overtreatment.

A large European study with a 13-year follow-up shows that prostate-specific antigen (PSA) screening for prostate cancer can reduce deaths from the cancer by about one-fifth. But, the study authors do not believe that these benefits outweigh the harms that are caused by treatments and invasive biopsies, both of which can result in long-term adverse effects for men, including impotence, incontinence, and gastrointestinal complications. The study was published in the Lancet.

The European Randomized Study of Screening for Prostate Cancer (ERSPC) showed significant reductions in prostate cancer mortality after 9 years and 11 years of follow-up. PSA screening reduced prostate cancer deaths by 15% at 9 years and by 22% at 11 years.

The current 13-year follow-up shows that there was no further improvement in reduction of prostate cancer mortality, which was about 21%. Those men who were actually screened had a 27% lower risk of dying from prostate cancer.

The number of men needed to be screened to prevent a single prostate cancer death decreased from 1,410 men after 9 years of study to 781 men after 13 years of study, a steady decrease. The number needed to be diagnosed with prostate cancer and subsequently treated to prevent a single death from prostate cancer decreased from 48 to 27 men.

The ERSPC enrolled more than 162,000 men between the ages of 50 and 74 from eight European countries (Belgium, Finland, France, Italy, the Netherlands, Spain, Sweden, and Switzerland) and randomly assigned them to either screening every 4 years (every 2 years in Sweden) or no screening. Men were referred for a biopsy if their PSA score was greater than 3.0 ng/mL. The study began in 1993.

At the 13-year follow-up mark, 7,408 men were diagnosed with prostate cancer in the screening group compared with 6,107 men in the control group.

“Despite our findings, further quantification of harms and their reduction are still considered a prerequisite for the introduction of populated-based screening,” concluded study author Fritz Schröder, MD, of Erasmus University Medical Center in Rotterdam, Netherlands, and colleagues.

“The main weakness of screening is a high rate of overdiagnosis and overtreatment. We conclude that the time for population-based screening has not arrived,” the authors further stated. “In the present situation, early diagnosis cannot be refused to men who are well-informed and request to be tested. Information must concentrate on the occurrence of overdiagnosis, which is also the main target of future research. Multiparametric MRI and the developments of new markers are the hope for the future. In the meantime, available instruments with multivariate risk stratification must be applied.”

As of 2011, the US Preventive Services Task Force does not recommend prostate cancer screening for healthy men. This recommendation is based on the 10-year US-based Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, as well as from the current study reported here.

In a commentary on these results, Ian Thompson, MD, of the University of Texas Health Science Center at San Antonio, and Catherine Tangen, DrPH, of the Fred Hutchinson Cancer Research Center in Seattle, stated that PSA screening is “imperfect” and that “with an enormous reservoir of cancers in aging men, there is a major risk of detection of many cancers that will never cause symptoms or death.”

The commentary authors also pointed out that screening does not always prevent prostate cancer–related deaths. “It is this trio of drawbacks (overdetection, treatment complications, and disease progression) that leads to the uncertainty about the role of screening,” they said.

“The new findings from ERSPC are crucially important. In future publications from the study, the distribution of prostate cancer deaths by Gleason score and PSA at diagnosis will be important to understand how to tailor screening and treatment,” Thompson and Tangen concluded.