PSA Testing – What’s One to Do?

The use of prostate-specific antigen (PSA) testing to screen for prostate cancer has recently become controversial. Two large studies have been reported in the New England Journal of Medicine, one from Europe and one from the USA. Both studies are still ongoing, but interim results seemed important enough for the Journal to publish them now.

The European study, which started in the early 1990s, involved eight countries – Belgium, Finland, France, Italy, Netherlands, Spain, Sweden, and Switzerland – with an average follow-up of 9 years. The analysis included 162,000 men who were randomly assigned to screening with a PSA determination and 4-yearly follow-ups thereafter, or to no screening. Men with a PSA of 3 ng/mL or more were offered a prostate biopsy. In the screened group the incidence of a prostate cancer diagnosis was 8.2%, vs. 4.8% in the control group. And there were 20% fewer deaths from prostate cancer in the screened group than in the controls.

The US study ran from 1993 through 2001. Over 75,000 men at 10 US centers were randomly assigned to annual screening (annual PSA testing and a digital rectal exam) or to ‘usual care’ – which included screening in some cases (about 40% to 50% of the controls). After 7 years, screening was associated with an increase of 22% in the rate of prostate cancer diagnosis. The standard PSA threshold of 4 ng/mL or a positive rectal exam was used for diagnosis. The death rate from prostate cancer per 10,000 men-years was 2.0 in the screened group, vs. 1.7 per 10,000 men-years for the ‘usual care’ subjects. This was not a statistically-significant difference, and the investigators concluded “After 7 to 10 years of follow-up, the rate of death from prostate cancer was very low and did not differ significantly between the two study groups”. The investigators suggest that the improvement in the treatment of prostate cancer over the years of the study was sufficient to blunt the likely difference in death rate between the two groups.

What is one to conclude? Not much, really. Here’s what the Chief Medical Officer of the American Cancer Society had to say: “These early results from two major trials suggest that if prostate cancer screening is beneficial, the benefit is small in terms of lives saved. For several years, many experts had anticipated these studies would show a small number of men will benefit from prostate screening, but a large number of men will be treated unnecessarily. And that's what these studies show.”

It seems that men at average risk should decide whether or not to be screened based on their own concerns and situation and after discussing the benefits and limitations of screening with their doctor. In other words, go ask you doctor!