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The Prostate-Specific Antigen (PSA) Test is used by doctors in many regions of the world to test for prostate cancer and other prostate disorders.

Some people recommend its use for screening - i.e. detecting cancers in the broad (asymptomatic) population. One proponent is prostate-cancer-sufferer and former-mayor-of-New-York Rudy Guiliani, who claimed:

"I had prostate cancer seven years . My chance of survival in the US is 82%; my chance of survival if I was here in England [where screening is not done] is below 50%."

Those figures have been questioned (There is a good summary near the end of this edition of Chance News, an excellent source for corrections of misued statistics.) which leads me to pose a specific question for skeptical analysis:

Does routine screening for prostate cancer save lives, cost-effectively?

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    Matt, I did a bigger-than-typical rewrite of your question that I thought I should bring to your attention. A lot of the information in the question was useful, but belongs in an answer. Putting it in the question made it harder to understand the claim and gave a perception of bias. I hope you find the edit doesn't misconstrue the original question. – Oddthinking Oct 14 '11 at 8:06
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    @Oddthinking Thanks for the rewrite. I'm still trying to get the balance right here as I learn what the community wants to see in questions and answers. In fact, your rewrite is a model of how to improve answers in an encouraging and positive way especially compared to some other feedback I've seen here. Thanks. – matt_black Oct 14 '11 at 8:28
  • I think the numbers come from how advanced the cancer is when it is first detected. If there is not screening then the cancer is more likely to be advanced when it is first detected. I do not think he is saying that if he has had prostate cancer for 7 years he is 32% more likely to survive if treated in the US. Just that being in the US he is 32% more likely to have it detected in time to treat it and save his life. – Chad Oct 14 '11 at 15:34
  • @Chad You are sort of right. Giuliani quoted stats based on 5-year survival rates which are meaningless. He thought they meant something useful about mortality when any expert would have told him they don't. Early detection increases the 5-year survival even if treatment is useless and you die on exactly the same day. – matt_black Oct 14 '11 at 16:22
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Short summary (source: recent review in the BMJ)

Major evidence based guidelines recommend against the prostate specific antigen (PSA) blood test for prostate cancer screening because:

  • The test is unlikely to prevent you from dying of prostate cancer over 10-15 years or help you live longer
  • Elevated PSA values are common and lead to additional tests that have harms
  • PSA testing finds many cancers that will not cause health problems
  • Once we find cancer it is hard not to treat it
  • Treatments have harms that occur early, can be serious, and may persist, but have very little, if any, benefit
  • By choosing not to have the PSA test you can live a similar length of life, have little to no difference in your risk of dying from prostate cancer, and avoid the harms associated with tests, procedures, and treatments

Mass screening for prostate cancer doesn't save lives and probably causes more harm than good.

This conclusion defies popular intuition about the benefits of screening in general and the typical practice in the USA. Before examining the evidence it is worth a quick summary of why the popular intuition is wrong here and in many other areas of medical screening. Gerd Gigerenzer and his team reviewed what is known in depth in their paper: Helping Doctors and Patients Make Sense of Health Statistics. The paper should be compulsory reading for anyone discussing medical statistics.

One key conclusion (my emphasis):

We show that information pamphlets, Web sites, leaflets distributed to doctors by the pharmaceutical industry, and even medical journals often report evidence in nontransparent forms that suggest big benefits of featured interventions and small harms. Without understanding the numbers involved, the public is susceptible to political and commercial manipulation of their anxieties and hopes, which undermines the goals of informed consent and shared decision making.

This goes some way to explaining the difference between evidence and perception about screening.

More relevant to this answer, the article quotes Sir Muir Gray (Chief Knowledge Officer of the NHS):

All screening programmes do harm; some do good as well, and, of these, some do more good than harm at reasonable cost.

So what does the clinical evidence say about the balance of good and had and the number of lives saved by screening?

Expert recommendations have recently been turning strongly against screening. A news story in a recent BMJ reports that the US expert group has found against screening (my emphasis):

The prostate specific antigen (PSA) test should not be used to screen men for prostate cancer because it is unlikely to save lives and can cause harm, says an independent panel of experts.

The US Preventive Services Task Force, an independent body of 16 experts that evaluates evidence to grade devices and rank preventive services, announced its recommendation against prostate cancer screening of all US men on 7 October. In a statement it said that there was “moderate certainty that PSA-based screening for prostate cancer has no net benefit.”

Part of this conclusion derives from new long term studies recently published (this one from the BMJ in 2011 which concluded:

After 20 years of follow-up the rate of death from prostate cancer did not differ significantly between men in the screening group and those in the control group.

There have also been recent meta-anlyses of many of the earlier studies. Here is the conclusion from a BMJ review in 2010:

Six randomised controlled trials with a total of 387 286 participants that met inclusion criteria were analysed. Screening was associated with an increased probability of receiving a diagnosis of prostate cancer (relative risk 1.46, 95% confidence interval 1.21 to 1.77; P<0.001) and stage I prostate cancer (1.95, 1.22 to 3.13; P=0.005). There was no significant effect of screening on death from prostate cancer (0.88, 0.71 to 1.09; P=0.25) or overall mortality (0.99, 0.97 to 1.01; P=0.44). All trials had one or more substantial methodological limitations. None provided data on the effects of screening on participants’ quality of life. Little information was provided about potential harms associated with screening.

Conclusions The existing evidence from randomised controlled trials does not support the routine use of screening for prostate cancer with prostate specific antigen with or without digital rectal examination.

A Cochrane review in 2009 comes to similar conclusions.

Note one of the problems in many studies (see italicised text in the above quote) is that potential side effects of over treatment are likely to be missed. This is significant as they are serious (see the Wikipedia article) and understating them is likely to understate the harm of screening.

Perhaps the best summary is given by the man who invented the test in a New York Times article in 2010:

I never dreamed that my discovery four decades ago would lead to such a profit-driven public health disaster. The medical community must confront reality and stop the inappropriate use of P.S.A. screening. Doing so would save billions of dollars and rescue millions of men from unnecessary, debilitating treatments.

So it seems safe to conclude that Prostate cancer Screening doesn't save lives and may cause significant harm.


Update

A recent review in the BMJ in early 2013 adds to the consensus evidence above. The abstract concludes:

Prostate cancer screening with the PSA blood test results in at most a small reduction in prostate cancer mortality and leads to considerable diagnostic and treatment related harms Physicians should recommend against PSA screening for prostate cancer Most men with prostate cancer detected by PSA testing have tumours that will not cause health problems (overdiagnosed), but almost all undergo early treatment (overtreated).

It also suggests a useful guide for physicians who want to be honest with their patients about the issues:

Prostate cancer screening messages for men Major evidence based guidelines recommend against the prostate specific antigen (PSA) blood test for prostate cancer screening because:

  • The test is unlikely to prevent you from dying of prostate cancer over 10-15 years or help you live longer
  • Elevated PSA values are common and lead to additional tests that have harms
  • PSA testing finds many cancers that will not cause health problems
  • Once we find cancer it is hard not to treat it
  • Treatments have harms that occur early, can be serious, and may persist, but have very little, if any, benefit
  • By choosing not to have the PSA test you can live a similar length of life, have little to no difference in your risk of dying from prostate cancer, and avoid the harms associated with tests, procedures, and treatments

This seems to summarise the situation well.

  • The closing blockquote would almost be worth putting at the top as a tl;dr; – Benjol Aug 21 '14 at 4:47
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    I have a problem with one bit here: "By choosing not to have the PSA test you can live a similar length of life, have little to no difference in your risk of dying from prostate cancer". The second part is false--by having the test you lower your risk of dying due to prostate cancer. It's just needless treatment causes as much of an increase as the benefit. – Loren Pechtel Mar 11 '18 at 2:13
  • The point of @LorenPechtel is important IMO. While this answer indeed answers the question about the general benefit of routine screening, the numbers given by Giulani can still be accurate (given that he had prostate cancer). – Muschkopp Mar 12 '18 at 9:53
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    @LorenPechtel Even that isn't obvious. Many of the reviews failed to find a significant change even in cancer-specific mortality (almost none fond a measurable change in all cause mortality). – matt_black Mar 12 '18 at 9:56
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    @Muschkopp Giuliani's numbers can be both correct and completely misleading. 5-year survival in prostate cancer is completely unrelated to mortality from prostate cancer. So his numbers are technically right but incredibly misleading giving the opposite impression to the truth. The point being that screening improves 5-year survival even if the day every patient dies is unchanged at all by screening. – matt_black Mar 12 '18 at 10:00

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