The UK currently has national screening programs for bowel, breast and cervical cancer. Increasing public awareness of prostate cancer has been associated with a growth in individual demands for screening. Lara Khoury reviews the evidence for national screening programs for prostate cancer.

The advent of the Internet has brought the public the ability to find out vast quantities of information about any disease or condition they wish to research. With this knowledge comes power, and the opportunity for patients to request tests they might never have known about in the pre-Internet era. This has pros and cons, as patients feel more in control, but may also start to make requests the healthcare provider feels are unwarranted. It is highly likely that patients’ increasing knowledge has led to an increase in requests for individual screening for prostate cancer [1]. This re-opens the hotly debated topic regarding introduction of a national screening programme for prostate cancer in countries which are yet to do so, bringing them into line with countries like America, who have been running a screening programme for many years. Prostate cancer incidence continues to increase, with more than 500,000 new diagnoses a year, resulting in over a quarter of a million deaths worldwide [2]. This makes it the third biggest cancer killer in men after lung cancer, but does this merit the introduction of a screening programme? The answer lies in the availability of appropriate and accurate screening tools.

Currently, the mainstays of prostate cancer screening programmes are the prostate specific antigen blood test (PSA) and digital rectal examination (DRE), although the accuracy of each has been brought into question. Elevated PSA levels can be suggestive of prostate cancer but also indicative of other prostate problems. In fact, 66% of men with raised PSA are cancer free [3]. Palpable masses are easily missed with DRE and, of those palpable, many are benign. Further, the DRE has a false positive rate of 40-50% [3, 4]. The inaccuracy of both tests suggests men may be sent for unnecessary additional testing (such as a biopsy), causing distress on the part of the patient as well as extra burden in countries with a National Health Service, such as the UK. Moreover, the acceptability of the tests to patients is questionable, due to their inaccuracy and invasive nature. The tests do not distinguish between fast and slow growing cancer; the majority of men having the latter, which will likely never become clinically important, suggesting population screening may be redundant [5].

Doubts regarding the efficacy of treatment have also been raised. Even if acceptable screening tools could be employed, treatment options are thought to be unacceptable [6]. Due to the slow growing nature of many prostate cancers, doctors usually employ ‘watchful waiting’ rather than another treatment [7]. This suggests a suitable alternative for early stage cancer does not exist, rendering a screening programme less useful and causing extra worry for patients. In addition, treatments that are employed carry significant risk of side effects, with more than 80% of men thought to suffer erectile dysfunction following radiotherapy or radical prostatectomy [8]. One paper went as far as to say “evidence is limited for the benefits of treatment…whereas the evidence for harm is clear” [9].

Despite all this, imagine for a minute that both screening tools and treatment were good enough to warrant a screening programme, would one actually make a difference? Mortality rates in the UK compared to America has shown that despite increased incidence in the US (due to high detection rates through their screening programme), mortality rates between the two countries remain similar [10]. This suggests that without better treatment, a screening programme would make little difference in the fight against prostate cancer.

In fact, many countries around the world have argued against national screening programmes for prostate cancer on different grounds. Figures from the US state of New Mexico show that even though screening increased incidence rates in early prostate cancer, screening decreased mortality rates by less than 2 in 100,000 sufferers [11]. A study of over 2000 Spanish men found that due to the inaccuracies in PSA testing and DRE, in order to find one cancer, 6.8 biopsies had to be performed, making a national screening programme costly and unproductive [12]. A Swedish analysis showed that even though radical prostatectomy decreased disease-specific mortality, there was no significant difference between surgery and watchful waiting on overall survival [13]. Finally, a study in Canada found that screening actually decreased quality adjusted life expectancy (QALE), proving the point that screening tools and treatment options are often not acceptable to the population as a whole [14].

Overall, evidence suggests national prostate cancer screening programmes are not currently justified due to ineffective screening tools and little impact on mortality [3, 9, 10]. It would appear education may be the best public health intervention, reducing inequalities in healthcare access due to lack of knowledge about available tests, and also working towards decreasing the embarrassment some men feel, allowing men to request testing when necessary, rather than subjecting older men to unnecessary testing .

As new information regarding screening tools and treatments comes to light, their possible role in screening needs to be evaluated, and thus the information given to the public adjusted accordingly, ensuring the highest quality service is provided to men who wish to be screened on an individual basis. With the advent of better tests/treatment and the possibility of genetic testing in the future, screening programmes may be in the public interest. However, in the present day, it seems there is little to justify them.

Lara Khoury
Fourth-year medical student
Newcastle Upon Tyne Medical School
l.d.khoury@newcastle.ac.uk

[1] Richards R. Letter about the implications for pathology of the GP resource pack on PSA testing. Available from: http://www.dh.gov.uk/PublicationsAndStatistics/LettersAndCirculars/DearColleagueLetters/DearColleagueLettersArticle/fs/en?CONTENT_ID=4006408&chk=WEnYaO (Accessed 6 May 2007).

[2] James M.L. Prostate Cancer (early). Available from: http://clinicalevidence.bmj.com/ceweb/conditions/msh/1805/1805_background.jsp (Accessed 13 September 2007)

[3] Selley S, Donovan J, Faulkner A, Coast J, Gillatt D. Diagnosis, management and screening of early localised prostate cancer. Health Technology Assessment 1997; 1 (2).

[4] Reissigl A., Pointner J. and Horninger W. et al., PSA-based screening for prostate cancer in asymptomatic younger males: pilot study in blood donors, Prostate 1997; 30: 20-25.

[5] Johansson J.E. Expectant management of early stage prostate cancer: Swedish experience. Journal of Urology 1994; 152 (2) Part 2: 1753-1756.

[6] G Davey Smith, S Ebrahim and S Frankel, How policy informs the evidence, BMJ 2001; 322:184-185.

[7] Whitmore W.F. Jnr. Localised prostate cancer: management and detection issues. Lancet 1994; 343: 1236-67

[8] Siegel T, Moul J, Spevak M, Alford G, Costabile R. The development of erectile dysfunction in men treated for prostate cancer. J Urol 2001; 165: 430-435

[9] Frankel S., Davey Smith G., Donovan J., Neal D. Screening for prostate cancer. The Lancet 2003; 361: 112-1128.

[10] Shibata A., Ma J., Whittemore A.S. Prostate Cancer Incidence and Mortality in the United States and the United Kingdom. Journal of the National Cancer Institute 1998; 90(16): 1230-1231.

[11] Gilliand F., Becker T.M., Smith A., Key C.R., Samet J.M. Trends in Prostate Cancer Incidence and Mortality in New Mexico Are Consistent with an Increase in Effective Screening. Cancer Epidemiology, Biomarkers & Prevention 1994; 3: 105-111.

[12] Martin E., Lujan M., Sanchez E., Herrero A., Paez A., Berenguer A. Final results of a screening campaign for Prostate cancer. Eur Urol 1999; 35(1): 26-31.

[13] Holmberg L., Bill-Axelson A., Helgesen F., Salo J.O. et al. A Randomized Trial Comparing Radical Prostatectomy with Watchful Waiting in Early Prostate Cancer. The New England Journal of Medicine 2002; 347: 781-789.

[14] Krahn M.D., Mahoney J.E., Eckman M.H., Trachenberg J., Pauker S.G., Detsky A.S. Screening for prostate cancer. A decision analytic view. JAMA 1994; 272(10): 773-780.

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