Cancer Research UK : Prostate Cancer screening and prevention

Prostate Cancer screening and prevention

Prostate cancer affects many men and most cases are diagnosed clinically when the disease is widespread and incurable. An accurate method of detecting the disease at an earlier stage when there is a better chance of cure is highly desirable.

Since the advent of PSA testing in the 1990s, informal screening of asymptomatic men has taken place but there are a number of ways in which population screening for prostate cancer fails to meet accepted screening criteria.

All three screening tests available (DRE, transrectal ultrasound [TRUS] and the measurement of PSA levels) have drawbacks.

Of the three, the PSA test is the most acceptable and reliable but even so there are problems. For example:

Lack of specificity. Only about a quarter to a third of asymptomatic men with abnormally high PSA levels will have prostate cancer. Up to two thirds of men with elevated PSA levels will not have prostate cancer but will suffer the anxiety, discomfort and risk of follow-up investigations.1
Lack of sensitivity. Up to 20% of all men with prostate cancers have normal PSA levels.
The PSA test has not been standardised. Inter-laboratory variability has been identified, and it is becoming clear that the levels of PSA need to be adjusted for a number of factors including age, the ratio of PSA serum concentration to gland volume and the free:total PSA ratio.2 The UK Prostate Cancer Risk Management Programme (see Future section below) aims to introduce a standardised test with systematic and standardised follow-up for men with raised PSA levels. A strict preparation protocol also needs to be followed if standard results are to be obtained.

The natural history of the disease is poorly understood. As a result, it is not always possible to predict reliably which tumours will be aggressive and which require little or no treatment. A proportion of patients therefore will receive unnecessary treatment, some with considerable side-effects.

Recently, studies carried out assessing tumour aggressiveness in relation to PSA doubling time have found that this is a strong indicator of risk. Monitoring changes in Gleason grade by carrying out repeat biopsies at regular intervals can also be used to predict the likelihood of tumour progression.

These developments may make prostate cancer screening using the PSA test a more effective procedure than it has been to date.3 Change in PSA levels can also be a good indicator for success of treatment, and for survival.4

Despite this, there remains a lack of consensus on the best treatment for early stage prostate cancer picked up through PSA testing or other screening tests, and an absence of evidence that such screening reduces mortality.

Screening trials are underway in a number of countries including the USA5 and Europe6-7 but it will be some years before results are known.

In the meantime it is essential that full and clear information on screening and its possible consequences is provided so that men can make informed decisions about their health care.8-10 Indiscriminate use of PSA testing should be avoided and protocols on PSA use should be put in place. The use of PSA testing in men at high risk also needs to be assessed.

A recent study has assessed the feasibility and psychosocial factors of PSA testing in first-degree relatives of prostate cancer patients. The positive predictive value of a referral to biopsy on the basis of the PSA reading was 24%, although the study was not large enough to be able to assess the effectiveness of PSA testing in this group.11-12

The future of prostate cancer screening and prevention

The Department of Health (DH) runs a Prostate Cancer Programme for the NHS. This covers research, treatment and a risk management programme specifically aimed at improving early detection and diagnosis.

In March 2001, two centres of excellence for prostate cancer research were announced in London and Newcastle. These are part-funded by the DH and partly by cancer research charities and industry.

Progress has been made within the NHS, with a 40% increase in the number of consultant urologists between 1997 and 2004, and more than 98% of patients now see a consultant within two weeks of an urgent GP referral.13

In late 2005, the Department of Health announced that it, and a confederation of prostate cancer charities, would be providing an extra £100,000 towards prostate cancer awareness.14

The Prostate Cancer Risk Management Programme includes guidelines for GPs and standardised information for patients. PSA testing is available for those men who, having considered the implications, wish to be tested.

Population screening will also be introduced if and when screening and treatment techniques are sufficiently developed.

All aspects of the disease are under scrutiny, from prevention to treatment. Prevention studies include research into how diet and exercise may affect risk, and in the USA chemoprevention for men at high risk is being evaluated.

Population screening to detect early potentially curable disease is being investigated in American and European trials. Research is underway to identify prognostic markers that can differentiate accurately indolent from aggressive tumours so that intensive treatment is targeted just to those who need it.

However, it will be several years before biological markers can be fully assessed for clinical use.

References

Klotz, L., PSAdynisa and other OSA-related syndromes; a new epidemic-a case history and taxonomy. Urology, 1997. (50): p. 831-2.PubMed
Dearnaley, D.P., et al., Diagnosis and managment of early prostate cancer. Report of a British Association of Urological Surgeons Working Party. BJU International, 1999. 83: p. 18-33.PubMed
Klotz, L., Active surveillance with selective delayed intervention: using natural history to guide treatment in good risk prostate cancer. J Urol, 2004. 172(5 Pt 2): p. S48-50; discussion S50-1.PubMed
D'Amico, A.V., et al., Preoperative PSA velocity and the risk of death from prostate cancer after radical prostatectomy. N Engl J Med, 2004. 351(2): p. 125-35.PubMed
Gohagan, J.K., et al., Prostate cancer screening in the prostate, lung, colorectal and ovarian cancer screening trial of the National Cancer Institute. J Urol, 1994. 152(5 Pt 2): p. 1905-9.PubMed
Auvinen, A., et al., Screening for prostate cancer using serum prostate-specific antigen: A randomised, population-based pilot study in Finland. Br J Cancer, 1996. (74): p. 568-72.PubMed
Rietbergen, J.B., et al., The changing pattern of prostate cancer at the time of diagnosis: characteristics of screen detected prostate cancer in a population based screening study. J Urol, 1999. 161(4): p. 1192-8.PubMed
Chamberlain, J., et al., The diagnosis, management, treatment and cost of prostate cancer in England & Wales. Health Technol Assess 1997, 1997. 1(3): p.PubMed
Selley, S., et al., Diagnosis, management and screening of early localised prostate cancer. Health Technol Assess, 1997. 1(2): p.PubMed
NHS Centre for Reviews and Dissemination, Screening for prostate cancer. Effectiveness matters. 2 ed., ed. Vol. 2. 1997.Link
Melia, J., et al., The feasibility and results of a population-based approach to evaluating prostate-specific antigen screening for prostate cancer in men with a raised familial risk. Br J Cancer, 2006. 94(4): p. 499-506.PubMed
Sweetman, J., et al., Feasibility of familial PSA screening: psychosocial issues and screening adherence. Br J Cancer, 2006. 94(4): p. 507-12.PubMed
DH. New report sets out progress on prostate cancer. Reference number 2004/0400. 2004 Accessed Link
DH. Funding boost for prostate cancer awareness. Reference number 2005/0374. 2005 Accessed 2006 Link

Previous section - Symptoms and treatment

Prostate Cancer screening and prevention

The future of prostate cancer screening and prevention

References

Select the cancer you are interested in