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Prostate Screening: where are we now?

Not many topics in GP get more arguments going than prostate cancer screening – there are well-ignored guidelines, superstitions and lies, damn lies and statistics galore.  (I got a giggle out of this comic from @bungeechump 😉  – click the pic to enlarge)

MODERN MEDICINE. on Twitpic

There have been a few big studies out in the last 5 years – somehow these don’t get the airplay that other similar studies (eg, WHI into HRT) get.  So I thought I would look at the current state of play – what does the latest evidence say?  In true Broome Docs style I have opted for the easy way out and decided to ask an expert.

Dr Josh Quaas

: I am a faculty member in the residency program of the Department of Emergency Medicine, St.Luke’s-Roosevelt Hospital, New York, NY. I work clinically as an Emergency Medicine physician and am active in pre-med, medical student, and resident education. I have a variety of interests that span from EBM to trauma. I work with the NNT Group where I review and edit concise narratives of high level evidence. A significant caveat to my write-up here is that my perspective is that of an EBM partisan and emergency physician, a physician whose practice does not include prostate screening.
 wrote a literature review on prostate cancer screening for the NNT late in 2010.  He is a man who is truly up to date – having devoured the literature and produced his review “PSA screening for Prostate Cancer” at NNT.  In summary – he found that there was no benefit and potential harm from unnecessary prostate biopsy.  So I thought I would ask him 5 quick questions to further explore this often debated topic through the mind of a guy who really knows his stuff!  He we go:

5 quick Questions from Broome Docs to the man in the know….

There are 2 large randomized trials (both are still collecting longer term follow-up data): 1. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. 76,693 men aged 50-74 were randomized screening (PSA + DRE) versus usual care. This study has been criticized for having methodological flaws (contaminated control group, excessive screening prior to randomization, low biopsy rates). It found no mortality benefit to PSA screening. 2. The European Randomized Study of Screening for Prostate Cancer (ERSPC). 162,243 Subjects were randomized to screening (varied among different countries but was mostly PSA + DRE) versus no screening. The primary outcome was mortality due to prostate cancer. This study found a weak benefit favoring screening, The ERSPC authors report that 1410 men would need to be screened to prevent one additional death from prostate cancer during a 9-year period, which is also associated with 48 men needing to be treated for prostate cancer. When these 2 studies are combined with another 4 trials and the data is meta-analyzed, the summation shows NO net mortality benefit to screening. Hence the recent US Preventative Service Task Force rating the PSA test a “Grade D”: recommending against its use as there is moderate to high certainty that the test has no net benefit or that the harms outweigh the benefit. Djulbegovic, M., Beyth, R., Neuberger, M.M. et al. Screening for prostate cancer: Systematic review and meta-analysis of randomized controlled trials. BMJ 2010;341:c4543 doi:10.1136/bmj.c4543 Ilic D, O’Connor, D, Green S, et. Al. Screening for Prostate Cancer. Cochrane Library. 2010. DOI: 10.1002/14651858.CD004720.pub2

The studies above often included the DRE, however this variable was not specifically evaluated in the trials. The US Preventative Services Task Force concluded in 2008 that there is no evidence of benefit (or harm) to the DRE in prostate screening. It is interesting to note that there increasing evidence showing a lack of benefit for the DRE in other realms, including the evaluation of undifferentiated abdominal pain and in trauma (when unconcerned for spinal or direct rectal injury). The DRE, once a mainstay in the complete trauma and complete abdominal evaluations, is now practiced selectively, which is probably how it should be used for evaluation of the prostate.

A major problem with harms with any intervention is that they are poorly reported in the literature in general. Unfortunately this is also the case with PSA testing, as harms testing were poorly reported in all of the studies. Up to 75% of elevated PSA tests are false positive, which leads to anxiety and unnecessary tests. Since the test appears not to save lives, how many men ultimately have unnecessary prostatectomy (removing an indolent cancer that was not going to be fatal) and then have to deal with impotence and urinary difficulties? The long-term sequelae are serious: erectile dysfunction rates as high as 70%, partial urinary incontinence as high as 40%, and total urinary incontinence as high as 2% (reported rates vary considerably).

Almost all the trials looked at men 50 and over. I would say there is no evidence that I reviewed that would merit comment for men in their 40’s, though I am not aware of good data that supports testing that group.   [Ed note: as the incidence drops in younger men, we must be aware that the “bang-for-the-buck” value of a screening program also decreases. ]

Absolutely not. My current opinion is that there probably is no benefit to testing the asymptomatic man. Some PSA partisans feel that more follow-up will ultimately reveal benefit, especially in the strongest trial, the ERSPC study that did have a small mortality benefit. The current data indicate the PSA test clearly should not be ordered reflexively or blindly in all men; I think it reasonable to be done by some men (i.e. high risk or test-desiring patients) and their physicians who understand the limitations of the tests and still want to pursue this path, and all that it might entail.

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