PSA screening reduces prostate cancer mortality

To the Editor: I refer to the editorial by D G Burns entitled ‘Prostate cancer – is screening the solution?’¹ Although a number of relevant points are raised in his editorial, it is blatantly inaccurate to report that the European Randomised Study of Screening for Prostate Cancer (ERSPC) showed ‘little or no effect on mortality from the disease over a prolonged follow-up period’. At a median follow-up of 9 years there was a 20% relative reduction in rate of death from prostate cancer among men between the ages of 55 and 69 years.² In a subsequent publication, which corrected for non-attendance in men randomised to the screening arm and contamination (having a prostate-specific antigen test) in men randomised to the control arm, the risk reduction was even greater. In the men actually screened, the risk of dying of prostate cancer was reduced by up to 31%.³ Over-diagnosis and the large numbers needed to screen and treat to prevent one death are a concern. We should not be asking whether screening improves survival as there is good evidence to support that it does. We should rather ask whether we can afford it and whether we are prepared to accept the morbidity associated with treating a large number of patients who may not benefit from treatment.

Lisa Kaestner

Department of Urology

Groote Schuur Hospital

Observatory

Cape Town

lisalisa@live.co.za

1. Burns DG. Prostate cancer – is screening the solution? S Afr Med J 2011;101(9):634.

2. Schröder FH, Hugosson J, Roobol MJ, et al. Screening and prostate-cancer mortality in a randomised European study. N Engl J Med 2009;360(13):1320-1328.

3. Roobol MJ, Kerkhof M, Schröder FH, et al. Prostate cancer mortality reduction by prostate-specific antigen-based screening adjusted for nonattendance and contamination in the European Randomised Study of Screening for Prostate Cancer (ERSPC). Eur Urol 2009;56(4):584-589.

Dr Burns replies: Lisa Kaestner is correct in pointing out that in the ERSPC there was a 20% relative reduction in mortality from prostate cancer, but the other landmark USA-based Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial failed to show a similar mortality benefit over a 7 - 10-year period.1 , 2 These were both complex trials, and it is possible that the failure to confirm the findings of the ERSPC study may have been influenced by the lower number of men entered into the PLCO study (76 693 v. 182 000), and failure to correct for ‘contaminators’ in the control group in the USA study. However, it also confirms that screening of very large numbers of subjects was required to demonstrate any statistical mortality benefit, with substantial overtreatment and a very small proportion of men ultimately benefiting from such interventions. Based on these studies, it indeed seems appropriate to question whether this margin of clinical benefit is worth the financial and morbidity costs of population-based screening. In fact, recently the US Preventive Services Task Force is reported to have posted a preliminary draft recommendation against PSA-based screening for prostatic cancer in all age groups, based on the publication of the above two trials.3

1. Schroder FH, Hugosson J, Roobol MJ, et al. Screening and prostate-cancer mortality in a randomized European study. N Engl J Med 2009;360:1320-1328.

2. Andriole GL, Crawford ED, Grubb RL 3rd, et al., Mortality results from a randomized prostate-cancer screening trial. N Engl J Med 2009;360:1310-1319.

3. Brett Allen S. Journal Watch General Medicine. 27 October 2011.