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About Sense and Nonsense of the PSA Test

About Sense and Nonsense of the PSA Test

Photo: Blood ampullae in a lab

"Today, nobody would like to live without electric light", says Hartwig Huland, professor at the clinic for urology at the University Medical Centre in Hamburg-Eppendorf, Germany. "Nobody would like to live without PSA either. In medicine, it has brought us a large step forwards." The reason: If the doctor discovers prostate cancer early, the chances of healing are improved considerably. According to Huland the PSA test helps in revealing the presence of a tumour years in advance compared to a rectal examination.

"Using a PSA test for the early diagnosis of prostate cancer can do more damage than good", says the science journalist Dr. Klaus Koch. The reason: the idea of early diagnosis is to discover tumours that would lead to death when not treated. However, prostate carcinoma grow slowly and many men die with it, but not because of it. Moreover, Koch says: "The test's disadvantage is the high occurrence of false positive results. According to a German newspaper for practitioner's from 2006 the rate is around 75 per cent." This makes the test useless and also dangerous: The psychological effects for falsely diagnosed men are huge.

Use of the test not clearly verified

However, the PSA test is the only recognised for the early diagnosis of prostate cancer in medicine even though its use has not been scientifically proven. That is why compulsory health insurance fund in Germany does not pay for it. In addition, this is also the reason why the sense and nonsense to use the prostate specific antigen (PSA) as a marker for prostate cancer is controversially discussed.

In spite of all uncertainties surrounding this test many urologists recommend it to their patients. The German Society for Urology (DGU) considers the test appropriate in its guideline for early diagnosis of prostate cancer". They argue: better a stressful possibly unnecessary diagnosis than the news that the cancer was discovered too late. Indeed, that is where the critics start. "Some patients make their will when being informed about elevated PSA levels", Koch explains. He is one of the authors of the book "Myths of cancer prevention". However, besides the psychological strain caused by wrong diagnoses they also criticise overhasty treatments such as surgeries with the possible outcomes of incontinence or impotence.

A test with weak points

Most experts take these arguments seriously and advise a reasonable handling of test results. "If the levels of PSA in the blood are raised this does not necessarily mean cancer", Huland explains. Inflammations, a benign enlargement of the prostate gland or even a long lasting bicycle tour can increase its levels - another weak point of the test. On top of that there are uncertainties about the limit values: "Today, we know that four nanograms PSA per millilitre of blood is not the lower limit for prostate cancer," says Professor Kurt Miller, manager of the urological clinic of the Charité Berlin. "Some men also have cancer with PSA values less than four." Therefore, it should be more sensible to determine an individual PSA level as a base and to observe at regular intervals how fast PSA levels increase from there.

Due to the fact that prostate carcinoma grows fairly slowly doctors recommend the PSA test only when a patient has a life expectancy of at least another ten years. "In general we use the test only in men younger than 75", Professor Manfred Wirth explains, vice president of the DGU and director of the clinic of urology at the Academic Medical Centre Dresden. After the age of 75 the likelihood to die of another diesease is greater that to die from prostate cancer.

Thorough professional consultation is of most importance

Doctors warn of hastyful action. "A positive test result must not lead to hectic measures. The PSA test should rather be seen as a risk evaluation", says Miller of the Charité. The critic Koch agrees since according to him 30 to 50 percent of the men over 50 have small tumour nodules in the prostate – but only three percent die of it. The patient must be informed about facts likes this competently and in detail. Most important: The information needs to be given before the test in order tp prevent the patient to be completely thrown off course by a wrong diagnosis. However, nobody knows about the quality of consultation in doctor's offices.

Two studies should clarify the discussion about sense or nonsense regarding the PSA test. The "European Randomized Screening for Prostate Cancer" study (ERSPC) with 205,000 patients as well as the "Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial" (PLCO) in the USA with 148,000 patients examine whether the PSA test is suitable as a screening test and whether it can decrease the rate of men dying of prostate cancer. The only drawback: Critics and advocates must wait for the results another three years.

Simone Heimann
MEDICA.de

 
 

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