ROTTERDAM, The Netherlands, December 8 The effectivenessof PSA (prostate-specific antigen) screening on reducing prostate cancermortality has been given a boost with new data from the European RandomizedStudy of Screening for Prostate Cancer (ERSPC). This shows the true impact tobe far higher than previously reported - up to 31%.
Preliminary ERSPC findings* showed that screening reduced prostate cancerdeaths by 20%. This latest ERSPC analysis** corrects for non-attendance andcontamination to assess the effectiveness of PSA testing in those menactually screened: http://www.erspc.org.com.
From 1992, the ERSPC study randomized 162,000 men, aged 55 to 69, inseven European countries to either a screening arm or a control group. Thosescreened were given a blood test to detect PSA levels: if it was 3.0ng/ml ormore, they were offered a biopsy. Screening took place on average every fouryears. Mean follow-up was nine years.
In any randomized trial, some in the screening arm do not attend and somein the control group inadvertently receive a PSA test (contamination).Contamination makes it difficult to detect differences. This is believed tobe one reason why the Prostate Lung, Colon and Ovarian (PLCO) study failed todetect any significant reduction in mortality.
PSA cut off level of 3ng/ml is safer threshold for reducing biopsies
Using retrospective data from the Dutch arm, the ERSPC has shown thatusing a screening algorithm - an individual risk assessment - alongside PSAtesting can reduce the number of unnecessary biopsies. PSA testing issensitive but not specific, so elevated levels do not necessarily implycancer. Approximately 30% of detected cancers are non-aggressive - 'indolent'or slow growing.
Their findings, published in January 2010's European Urology (alreadyonline http://www.europeanurology.com/current-issue) suggest that a PSA cutoff level of 3ng/ml combined with an individual risk assessment would reducebiopsies by 33%. The majority of cancers potentially missed would beindolent, so there would be no benefit from active treatment. Increasing thePSA cut-off level from 3 to 4 ng/ml may save a similar number of biopsies,but will miss more clinically significant cancers.
*NEJM, March 2009
**European Urology, October 2009
SOURCE European Randomized Study of Screening for Prostate Cancer (ERSPC)