Rifts widen in prostate screening debate

Medical Tribune June 2009 P1&9
David Brill

American and European experts have diverged in their stances on prostate cancer screening, as debate intensifies over the benefits of prostate-specific antigen (PSA) testing.

The subject has held center stage since the publication of two major studies in March: one showed that PSA testing every 4 years reduced mortality by 20 percent but carried a high risk of overdiagnosis; the other showed that annual screening had no impact on death rates.

The American Urological Association (AUA) has since aligned itself with the first study – recommending PSA testing in all well-informed men, and lowering the age for a first test from 50 to 40. It has also adjusted its criteria for proceeding to biopsy.

The European Association of Urology (EAU), meanwhile, has advised against population screening until more data are available – warning of the dangers of overtreatment and calling for urgent development of new diagnostic markers and screening algorithms.

Singapore experts are taking a similar stance to their European counterparts, although they note that the lower incidence of prostate cancer in Asia makes screening less worthwhile than in Western populations.

The Singapore Urological Association (SUA) nonetheless intends to downplay the role of PSA screening in this year’s upcoming Prostate Awareness Month, according to Professor Kesavan Esuvaranathan, SUA president and senior consultant, department of urology, National University Hospital.

“I wouldn’t be in a hurry to recommend screening. We don’t know for sure whether there is a benefit,” he said.

“My feeling is that it’s too early to say that PSA screening is inappropriate, but I also think that it is probably wrong to unconditionally recommend PSA screening. I think we have to wait for the long-term results of these studies.”

Associate Professor Weber Lau, senior consultant, department of urology, Singapore General Hospital, also urged caution in the use of PSA testing, stressing the need to select the right patients.

“We are quite clear that screening is not a goal for Singapore at this juncture. For people who are asking to be tested, the key words are risk stratification,” he said.

“PSA can be used as a tool for early detection of prostate cancer in the right patients. But on the other hand it can be harmful too if used in health screening without understanding the risks of the patient group and the general health of the patient.”

The 20 percent mortality reduction with PSA screening was reported in the European Randomized Study of Screening for Prostate Cancer, which included 162,387 men aged 55 to 69 from seven countries. They were assigned to PSA screening every 4 years on average, or to no screening. [N Engl J Med 2009 Mar 26;360(13):1320-8]

After a median of 9 years’ follow-up, the adjusted rate ratio for prostate cancer death in the screening group was 0.80, as compared to the control group (95 percent CI, 0.65 – 0.98; P=0.04). The absolute risk difference was 0.71 deaths per 1,000 men – meaning that to prevent one death from prostate cancer, 1,410 men would need to be screened and an additional 48 cases would need to be treated.

The second study – the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial – included 76,693 men aged 55 to 74, recruited at 10 US centers. Men were randomized to annual screening – with PSA for 6 years and digital rectal exam for 4 years – or to the control group. [N Engl J Med 2009 Mar 26;360(13):1310-9]

After 7 years’ follow-up, there were 50 prostate cancer deaths in the screening group and 44 in the control group (rate ratio 1.13; 95 percent CI, 0.75 – 1.70). Ten-year data showed similar patterns but follow-up was only complete for 67 percent of patients at the time of publication.

Despite the lack of national recommendations, PSA tests are commonly offered in Singapore as part of executive health screens, according to Kesavan. This situation need not change in light of the studies, he said, but he emphasized the importance of explaining the potential consequences before testing.

“It would place the patient in a quandary if it was not explained properly and then he had an abnormal test. Then to put that worry to rest it would require him to undergo a biopsy.”