Prostate cancer screening

This page presents information on prostate cancer screening including PSA testing, the Prostate Cancer Risk Management Programme, and informed consent.

Prostate cancer affects many men and the disease is incurable when diagnosed at a late stage. An accurate method of detecting early, treatable disease is therefore highly desirable.

Three tests for prostate cancer are available, Digital Rectal Examination (DRE), Prostate Specific Antigen (PSA) measurement and transrectal ultrasound (TRUS) biopsy but all have drawbacks. 1, 2

Of the three, the PSA test is the most acceptable but there are problems. PSA is an enzyme produced by the prostate which can be measured in the blood. It is clear that a number of factors, other than the presence/absence of cancer, can affect the levels of PSA, such as the age of the man, obesity and the presence of benign prostatic hypertrophy. 3

Research into making the PSA test more accurate is ongoing and includes looking at PSA density (takes into account the size/volume of the prostate gland), velocity (how fast it rises over time), doubling time and the ratio between two different components of PSA, ‘free’ and ‘complexed’. 4, 5 Free PSA is associated with benign prostatic conditions and complexed PSA with cancer so their ratios may help to interpret total PSA levels, alongside DRE findings, previous biopsy results, ethnicity, prostate size and co-morbidities. 4

The main reasons why PSA testing is not at present suitable for population screening of asymptomatic men are summarised below.

1. Lack of sensitivity. Around 15% of men with a normal (measured as =4ng/ml) PSA level will have prostate cancer. 6 In other words, the test will provide them with false reassurance. 4
2. Lack of specificity. Conditions other than prostate cancer, such as BPE, prostatitis and lower urinary infections, can give rise to elevated levels of PSA. About two-thirds of men with an elevated PSA level (measured as > 4ng/ml) will not have prostate cancer but will suffer the anxiety, discomfort and risk of follow-up investigations. 2, 4
3. The natural history of prostate cancer is poorly understood. At present it is not possible to reliably predict which tumours will be aggressive and which will require little or no treatment. A proportion of patients with early, localised disease detected through PSA testing and then biopsy, will receive unnecessary treatment, with considerable side-effects.
4. There is a lack of consensus on the best treatment for early stage prostate cancer.
5. There is no evidence that screening reduces mortality. Screening trials are underway in the US, UK and in Europe but it will be some years before the results are known. 7-11

6. As a result of these problems, population screening is not recommended and instead the Department of Health launched the Prostate Cancer Risk Management Programme (PCRMP) in 2002. 5 One of its main aims is to provide clear and balanced information about the benefits and limitations of PSA testing. 4, 5

   Asymptomatic men can then make an informed decision about whether they wish to have a PSA test or not, after discussion with their primary care physician. Referral guidelines recommend that PSA levels take age into account with cut-off values of = 3.0ng/ml for men aged 50-59, = 4.0ng/ml for men aged 60-69 and >5.0ng/ml for men aged 70+. 12 Inter-laboratory variability has also been identified and the PCRMP recommends that only laboratories participating in the UK National External Quality Assessment Service (UK NEQAS) are used.