The long-running European Randomized Study of Screening for Prostate Cancer (ERSPC) has published its 11-year follow-up results. These add weight to their original findings by confirming that screening does significantly reduce death from prostate cancer. Appearing in the New England Journal of Medicine, the study finds that a man who undergoes PSA testing will have his risk of dying from prostate cancer reduced by 29%.
By extending the patient follow-up to an average of 11 years, the study shows that 31% fewer men than previously indicated would need to be diagnosed with cancer to save one life.
As Prof Fritz Schroeder, the international coordinator of the ERSPC study, explained: “Extending the follow up period strengthens the argument for screening. But it does not decide it. Even so, the risk reduction trend in our study is promising and it is imperative that we continue the follow-up. So far, only about 30% of all men in the study have died. If a larger reduction of prostate cancer mortality is seen by further extending the study beyond the current median of 11 years, we can determine with greater certainty whether the benefit of screening outweighs the disadvantages.”
The main downside to screening is over diagnosis ‒ the diagnosis of cancers that do not pose any threat to the patient because they are slow growing or ‘indolent’. Separate ERSPC findings already confirm that approximately 30% of detected cancers are unlikely to progress and cause a patient’s death. Even so, the patient has received a diagnosis of cancer and may face the side effects of ‘unnecessary’ treatment.
“Screening programmes for prostate cancer will not be feasible until the medical communities can confidently balance the risk of reducing death from prostate cancer with these unacceptably high levels over diagnosis and overtreatment,” added Prof Schroeder.
ERSPC is the world’s largest prostate cancer screening study and involves eight countries – Belgium, Finland, France, Italy, Netherlands, Spain, Sweden and Switzerland. Participants in the randomised study totalled 182,000, of which 162,000 men contribute to the core age group 55 – 69 (on which the 2012 report in NEJM is based). Men randomized to the group being offered screening were tested using the prostate specific antigen (PSA) marker, every two or four years with an average follow-up of 11 years. The cut-off value for deciding if further investigation was needed was set at a PSA level of 3.0 ng/ml or more. Men with this reading were then offered a biopsy.
Compared with the USA, individual PSA testing started late in most European countries and meant that only a relatively small number of men taking part in the control arm of the ERSPC study had previously taken a PSA test. This makes the ERSPC study fundamentally different from the US-based Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial where there was a high contamination rate in the control arm with at least 44% of participants already PSA-tested prior to being randomized into the study. The PLCO study has been unable to demonstrate any difference in prostate cancer mortality between the two arms of the study.
Currently, the only way for men with potentially insignificant cancers to avoid what could be unnecessary is to direct them towards an Active Surveillance programme. This offers them regular check-ups while delaying, at least temporarily, invasive treatment.