Prostate cancer screening

To the Editor: Prostate-specific antigen (PSA) screening is not recommended by the Royal Australian College of General Practitioners,1 nor is it approved as a screening test in the United Kingdom.2 A recent review article in the BMJ recommends reducing the rate of PSA testing as a way of reducing the incidence of prostate cancer.2 As a GP, I find it hard to accept this advice.

PSA testing is very helpful in detecting prostate cancer, but is not by itself diagnostic. The higher the PSA level, the more likely the diagnosis of prostate cancer, and the poorer the histological grading.3 Well differentiated disease (Gleeson score 6 or lower), carries a much better prognosis than poorly differentiated disease (Gleeson score 7 or higher).4

The largest published study on prostate cancer screening, the European Randomized Study for Prostate Cancer,5 found a 20% reduction in prostate cancer mortality at 9 years, and a 29% reduction at 11 years. One participating centre (Göteborg, Sweden)6 found a reduction in prostate cancer mortality of almost 50% in the screened group. However, the reduced death rate does come at a cost — 37 men need to be treated to prevent one death.

But are we to ignore the findings about mortality reduction?

The second largest published study is the United States Prostate, Lung, Colorectal and Ovarian cancer screening trial.7 After 10 years of follow-up, it found no benefit with screening. However, there are serious concerns about this trial, as almost half the men in the control group had already had a PSA test. Even allowing for that, there were more men with Gleeson scores of 8 to 10 in the control group.

To reduce the incidence of the unwanted side effects of both surgery and radiotherapy, and to show a greater benefit from treating prostate cancer, more consideration should be given to only treating those cancers which are poorly differentiated (Gleeson 7 or higher). Well differentiated disease is ideal for surveillance.

I believe there should be more PSA testing, not less. This will lead to more frequent diagnosis of less advanced prostate cancer. Without PSA screening, the number of men presenting with metastatic prostate cancer would be three times greater than is currently observed.8

I cannot see how current screening guidelines will help reduce the death rate from prostate cancer.