Authors: Emily Hargrave, Future Science Group
A paper recently published in The Lancet detailing an investigation of 162,000 men suggests that deaths due to prostate cancer could be reduced by approximately a fifth by screening for the disease. However, the results are described as controversial as screening exposes individuals to overdiagnosis.
The European Randomised study of Screening for Prostate Cancer study is a long-term study that began in 1993. Men between the ages of 50 and 74 years from Belgium, Finland, France, Italy, Netherlands, Spain, Sweden, and Switzerland were involved in the study and were randomized to receiving screening either every 4 years or no intervention. The exception was in Sweden, where participants were screened every 2 years. If PSA results were found to be above 3.0 ng/ml, individuals were referred for a prostate biopsy.
A 15% decrease in mortality due to prostate cancer was seen in the screening group at 9 years, and this increased to 22% at 11 years. Over the 13 years of follow-up, there was no further increase in the relative reduction of deaths due to prostate cancer in the screening group compared with the control group.
In absolute terms, the benefits of screening increased with longer follow-up. The number of men needed to be invited to be screened to prevent one death from prostate cancer fell from 1410 to 781 individuals at 9 and 13 years follow-up, respectively. Furthermore, to prevent one death due to prostate cancer, 48 men needed to be diagnosed and treated, which also fell to 27 at 13 year follow-up. In the screening group it was also seen that the risk of advanced prostate cancer was smaller.
This study, however, comes with controversy and limitations, as early screening is associated with overdiagnosis and exposure to treatments that are unnecessary. Fritz Schröder (Erasmus University Medical Center, The Netherlands) explains, “PSA screening delivers a substantial reduction in prostate cancer deaths, similar or greater than that reported in screening for breast cancer. However, overdiagnosis occurs in roughly 40% of cases detected by screening resulting in a high risk of overtreatment and common side effects such as incontinence and impotence.”
He also commented that “The time for population-based screening has not arrived. Further research is urgently needed on ways to reduce over-diagnosis preferably by avoiding unnecessary biopsy procedures, and reducing the very large number of men who must be screened, biopsied, and treated to help only a few patients. One promising approach is multiparametric MRI technology which may be able to selectively diagnose aggressive prostate cancers and avoid the diagnosis of many inconsequential tumors that generally grow so slowly that most men will die of other causes. But for now, men must to be given well-balanced information including the screening harms of over-diagnosis and overtreatment.”
Source: Schröder FH, Hugosson J, Roobol MJ et al. Screening and prostate cancer mortality: results of the European Randomised Study of Screening for Prostate Cancer (ERSPC) at 13 years of follow-up. Lancet doi: 10.1016/S0140-6736(14)60525-0 (2014) [Epub ahead of print].