Advise on pros and cons of PSA testing

More than half of Canadian men over the age of 50 have undergone a PSA test for early detection of prostate cancer.

Yet the prostate specific antigen test remains controversial, with scientists divided on its benefits and many patients unsure about what test results really mean.

To clear up the confusion, a leading cancer expert is recommending that the descriptors "normal" and "elevated" for PSA tests be abandoned.

Instead, Ian Thompson, chairman of the department of urology at the University of Texas Health Sciences Center at San Antonio, said physicians should take the time to advise patients on the merits and drawbacks of the blood test.

Then, if the patient decides to have a PSA test, the results should be judged only in conjunction with other risk factors, he said.

"If screening is requested by an asymptomatic man, the clinician should inform him of his risk of prostate cancer, incorporating findings for all known risk factors for the disease - family history, age, ethnicity, digital rectal examination findings, PSA level and the results of any previous prostate biopsies," Dr. Thompson said.

Writing in today's edition of the Canadian Medical Association Journal, he said that information is best summarized and evaluated using the prostate cancer risk calculator, a simple tool that is available online at:

Then, if the patient decides to have a PSA test, the results should be judged only in conjunction with other risk factors, he said.

"If screening is requested by an asymptomatic man, the clinician should inform him of his risk of prostate cancer, incorporating findings for all known risk factors for the disease - family history, age, ethnicity, digital rectal examination findings, PSA level and the results of any previous prostate biopsies," Dr. Thompson said.

Writing in today's edition of the Canadian Medical Association Journal, he said that information is best summarized and evaluated using the prostate cancer risk calculator, a simple tool that is available online at http://www.compass.fhcrc.org/edrnnci/bin/calculator/main.asp.

PSA is a protein produced by cells of the prostate gland, a walnut-sized organ located below the bladder and in front of the rectum. PSA is normally present in the blood at low levels, defined as zero to four nanograms per millilitre. Levels of four to 10 ng/ml are considered problematic.

Increased levels of PSA may suggest the presence of prostate cancer. However, PSA levels may be also elevated because of prostate infection, irritation, benign swelling of the prostate or recent ejaculation. Prostate cancer can also be present in the complete absence of an elevated PSA level. Further, PSA levels rise with age and can fluctuate.

Because of the high level of false positives and false negatives, PSA testing is not recommended for population-wide screening.

Dr. Thompson said that the most problematic aspect of testing is "evidence of high rates of over-detection." About 18 per cent of men are diagnosed with prostate cancer, but fewer than 3 per cent of men die of prostate cancer.

Still, tracking changes in PSA levels in individuals can be useful. And there is no doubt that the PSA test is used routinely.

A recent nationwide survey found that half of Canadian men over 50 had been tested for PSA levels, 72 per cent of them in the previous year.

However, "awareness, utilization and knowledge of the pros and cons of PSA screening vary considerably by region," Dr. Thompson noted.

Even the experts disagree. The Canadian Task Force of Preventive Health Care says that there is insufficient evidence to promote PSA testing. The Canadian Urological Association and the Prostate Cancer Alliance, for their part, say the test should only be performed after a detailed discussion between physician and patient.

Most, but not all, the provinces and territories cover the cost of the PSA test. Ontario, Quebec, British Columbia and Alberta do not pay for PSA as a screening test, but will pay after a diagnosis of prostate cancer in order to monitor the progress of the treatment.

This year, an estimated 22,300 men will be diagnosed with prostate cancer and 4,300 will die of the disease, the Canadian Cancer Society says.

Since the use of early detection tests for prostate cancer became fairly common in the 1990s, the prostate cancer death rate has dropped, but it is unclear whether this is a direct result of screening.

Source: TheGlobeandMail.com