Prostate specific antigen (PSA) is a common blood test used by doctors to assess whether an individual has prostate cancer. It also predicts the risk of developing prostate cancer sometime in the future. It’s a good blood test but not a perfect one and the risk of cancer does increase with increasing levels of PSA in the blood tested.
Doctors have improved the accuracy of the test by also looking at the rate the PSA rises every year, by modifying the interpretation of the results in accordance with the age of the patient, and measuring additional modifications of PSA.
The test is usually performed in conjunction with a digital rectal examination, and if the doctor feels the risk of cancer is sufficiently high, a recommendation may be made to visit a specialist urologist and to consider a prostate biopsy, which is the only way cancer can be formally diagnosed.
Some men won’t benefit from a blood test to screen for prostate cancer – those with less than ten years left to live, for instance, or men under 40 years old (because prostate cancer is extraordinarily rare for them). But for a man in his 40s, a single blood test can help predict the risk of both getting and dying of prostate cancer. And it can help doctors decide how closely he should be monitored.
Trials have shown a reduced likelihood of death from prostate cancer because of PSA testing for men between 50 and 70 years old with a greater than ten-year life expectancy. This is why PSA testing must continue to be available and offered to men in the appropriate age group.
But before I talk about the evidence for PSA screening, let me correct an offensive allegation published in the press last week – that surgeons recommend surgery for commercial gain.
All doctors are patient advocates and would never recommend a course of action unless they firmly believed that it was in their patients' best interests. This is exactly why 42% of men diagnosed in Victoria with low-risk prostate cancer are managed with surveillance. They are monitored and treated only if the disease worsens. This course of action demonstrates that urologists are not in a hurry to operate on those who won’t benefit. It’s also the formal position of our professional society.
Indeed, urologists are only likely to suggest treatment for men with higher-risk prostate cancer where the survival benefit of surgery over observation has been demonstrated.
Evidence for PSA’s effectiveness
Let’s start by looking at Cancer Council Victoria figures. The five-year survival of a man diagnosed with prostate cancer in the late 1980s, when PSA testing was first introduced, was 57%. It’s now 91%, which is a massive improvement. While treatment has also got better during that time, some of the improvement has clearly been the result of PSA-based testing and early detection.
What’s more, a European study of PSA screening (ERSPC) has shown a 31% reduction in the risk of dying from prostate cancer over nine years in men who were tested. In the Swedish arm of this study, which followed-up participants for 14 years, the reduction in the prostate cancer death rate was 44%.
The American PLCO trial didn’t show a difference in survival between screened and control groups. But it had numerous flaws, including the fact that over half the men who were not supposed to be tested actually were. So it’s hardly surprising that a difference between the tested and control groups was not detected.
Urologists often recommend conservative management of prostate cancer. Two studies – the Scandinavian prostate cancer group (SPCG-4) randomized trial and the prostate intervention versus observation trial (PIVOT) – have clearly shown that, over ten years, men with low-risk prostate cancer may not benefit from surgery, but younger men with larger or higher-grade cancers definitely benefit.
In those with an abnormal blood test, a subsequent biopsy will provide valuable information that can help doctors decide if their patient falls into the risk group that benefits from treatment. Without the blood test, the degree of risk will not be known, and men will run the risk of a higher chance of dying from prostate cancer.
Surgery can cause side-effects, such as urinary leakage or erectile dysfunction, in a small number of men, and that has a negative effect on quality of life. But it’s important to note that many men diagnosed with prostate cancer already have pre-existing age-related erectile dysfunction – and many are not bothered by this potential side-effect.
Nonetheless, it’s important that doctors have a frank and open discussion about such side-effects with patients and their partners so that people can make informed decisions about the benefits and harms of their treatment.
And consider this:
Does the public want a faceless committee telling them they can’t have PSA-based testing? A committee that tells them it’s better not to know and to bury their heads in the sand? Men have the right to make decisions about their own lives.
As a male in his fifties, I want the right to be tested, to have a cancer detected early and to make my own decision about whether I feel the risks posed by treatment outweigh the risks of the disease. I don’t want a faceless committee deciding on my behalf that they don’t think the risks of treatment are worth taking, when it has the potential to save my life. I can make that decision for myself with the help of my doctor and medical specialists.
Read the case against PSA testing