A new European study suggests that screening men from age 55 for prostate specific antigen (PSA) could cut deaths from prostate cancer by 20
per cent, although it may also lead to more cases of overdiagnosis.
The results of the European Randomized Study of Screening for Prostate Cancer (ERSPC) were published 18 March in the online issue of the New England Journal of Medicine, NEJM, and will appear in the print issue on 26 March. The findings are also being presented at the 24th Annual Congress of the European Association of Urology (EAU) in Stockholm, Sweden, this week.
The ERSPC, which started in the early 1990s and followed participants for 12 years overall, is the world's largest prostate cancer screening study to provide independently audited, robust evidence, for the first time, of the effect of screening on prostate cancer deaths, said the authors in a press briefing.
ERSPC initially involved 182,000 men aged 50 to 74 in eight countries: Belgium, Finland, France, Italy, Netherlands, Spain, Sweden and Switzerland, but this was reduced to 162,000 men aged 55 to 69 in seven countries once the men who had already been screened before were taken off the list.
The participants were randomly assigned to either a treatment group or a control group. The treatment group was offered PSA screening at an average of once every 4 years, while the control group did not have any screening. Men in the screening group whose PSA was found to be 3.0 ng/ml or higher were then offered a biopsy.
The researchers counted rate of death in both groups until the end of 2006; this was the primary outcome measure of the study.
The results showed that:
- In the PSA screening group, 82 per cent of the men accepted at least one offer of screening.
- During a median follow-up of 9 years, 8.2 per cent of the screening group and 4.8 per cent of the control group were diagnosed with prostate cancer.
- The rate of death from prostate cancer in the PSA screening group compared to the control group was 0.80 (ie 20 per cent lower, 95 per cent confidence interval, CI, 0.65 to 0.98, adjusted P=0.04).
- On average, every life saved came from screening 1,408 men from which 48 were diagnosed with cancer and received treatment.
"PSA-based screening reduced the rate of death from prostate cancer by 20 per cent but was associated with a high risk of overdiagnosis."
Prof Fritz Schröder who coordinated the ERSPC study explained that these findings show:
"PSA screening delivers a 20 per cent reduction in mortality from prostate cancer."
"This provides decision makers on screening policies with important new data on the effectiveness of PSA testing in preventing deaths," he added.
But, he cautioned that the study is not yet finished, there are more outcomes to be assessed, such as the effects on healthcare costs and quality of life of the patients, and policymakers need to see these figures before making any decisions that affect national screening programs.
Prostate cancer is the second leading cause of death from cancer around the globe. Other findings from the ERSPC study have already shown that about 30 per cent of detected prostate cancers are non-aggressive and slow growing. This is an unavoidable overdiagnosis characteristic of all cancer screening, wrote the authors in a press statement, and they suggested that active surveillance (also called "watchful waiting") might be the right approach to avoid invasive treatment too early.
Another US study in the same issue of NEJM, based on 76,000 men, found there was no significant difference in mortality between men who had PSA tests and men who were just monitored.
According to the BBC, the ERSPC results have prompted a review of the UK's current prostate cancer screening policy. At the moment in the UK, routine PSA screening is not offered by the NHS, although men over 45 can ask their doctor for one.
Health Minister for England, Ann Keen, told the BBC that they will be asking the UK National Screening Committee to review the evidence on prostate cancer screening and make recommendations.
However, some experts will caution that any increase in PSA screening should be accompanied by tests that differentiate between slow and aggressive prostate cancers so that thousands of men with tumors that are not going to seriously harm or kill them don't undergo expensive and unnecessary treatments which also bring the risk of side effects such as impotence and incontinence.
"Screening and Prostate-Cancer Mortality in a Randomized European Study."
Schroder, Fritz H., Hugosson, Jonas, Roobol, Monique J., Tammela, Teuvo L.J., Ciatto, Stefano, Nelen, Vera, Kwiatkowski, Maciej, Lujan, Marcos, Lilja, Hans, Zappa, Marco, Denis, Louis J., Recker, Franz, Berenguer, Antonio, Maattanen, Liisa, Bangma, Chris H., Aus, Gunnar, Villers, Arnauld, Rebillard, Xavier, van der Kwast, Theodorus, Blijenberg, Bert G., Moss, Sue M., de Koning, Harry J., Auvinen, Anssi, the ERSPC Investigators.
N Engl J Med Online first, 18 March 2009.
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Sources: Journal Abstract, European Association of Urology, BBC.
Written by: Catharine Paddock, PhD