The Clinical Guidelines Committee of the American College of Physicians Indicates that for Many Men, the Potential Harms of Undergoing PSA Screening Outweigh its Unreliable Forecasting Value

09 April 2013

Citation — to the Committee’s guidance statement

Amir Qaseem, Michael J. Barry, Thomas D. Denberg, Douglas K. Owens, and Paul Shekelle, Screening for Prostate Cancer: A Guidance Statement From the Clinical Guidelines Committee of the American College of Physicians, Annals of Internal Medicine (early online publication, 09 April 2013)

Why read the Guidance Statement?

The article correctly balances the weight of previous research on the advisability of prostate-specific antigen (PSA) screening in varying cancer risk groups.

First, why would a good prostate cancer screening test be useful?

From the Guidance Statement:

Among cancer-related deaths in men, prostate cancer is the second-leading cause (4), representing 11.2% of such deaths (5). An estimated 2.3 million Americans have prostate cancer (5). In 2012, approximately 241 000 men are expected to be diagnosed with prostate cancer and 28 000 are expected to die of it (6).

© 2013 Amir Qaseem, Michael J. Barry, Thomas D. Denberg, Douglas K. Owens, and Paul Shekelle, Screening for Prostate Cancer: A Guidance Statement From the Clinical Guidelines Committee of the American College of Physicians, Annals of Internal Medicine (early online publication, 09 April 2013) (at Abstract, Guidance Statement 2)

What complicates the prostate cancer screening test idea? — The majority of men, even those with prostate cancer, die of something else

From the Statement:

Although 1 in 6 men (16.7%) will receive a diagnosis of prostate cancer in their lifetime (1), only 2.9% will eventually die of the disease (2).

The proportion of men who are diagnosed with prostate cancer but never have associated clinical symptoms is difficult to estimate, but it may range from 23% to 66% (3).

An ideal screening test would combine specificity with a reasonably sound prognostication

A screening test that cannot give “me” an idea of whether the illness (that it says I have) is going to:

(i) manifest clinically

and

(ii) do so in noticeably “bad” ways, given my current medical context —

is not a very good screening device.

For example, how would you react to a screening test that says you’re going to die someday, at a possibly advanced age, but cannot statistically foretell the cause, or even the scope of the suffering (if any) that you will undergo?

Scientific uncertainty is compounded by our failure to actually test our interventions

If you are not knowledgeable in the prostate cancer screening field, consider this — the two main screening tests aren’t that great:

The 2 tests generally used for screening and discussed in this guidance statement include the prostate-specific antigen (PSA) test and digital rectal examination (DRE).

The PSA test is more sensitive than DRE, and no screening trials have evaluated the utility of DRE alone.

Clinical trials of PSA-based screening have focused on absolute PSA threshold levels to guide biopsy decisions.

Although various strategies can be used to try to improve the diagnostic performance of the PSA test, such as PSA velocity (change in PSA over time), PSA density (PSA per unit volume of the prostate gland), or free PSA, these strategies have not been evaluated in clinical trials of screening and are not discussed in this guidance statement.

Summarizing what we have, so far

An unreliable screening test for a disease that may not cause problems at all, much less kill the majority of people who actually have it.

Compound these uncertainties — with the professional self-interest that has hampered coming to grasp with data, which casts doubt on the medical and financial validity of routine PSA screening

PSA testing has been controversial for some time — at least among scientifically minded professionals, medical analysts, and occasionally harmed patients.

However, the victory of scientifically quantitative common sense — all advising against PSA screening in low and average risk men — has been impeded by self-interested components of the medical establishment. These groups have obvious financial interests in continuing PSA testing and in providing the frequently “advised” follow-up biopsy and surgical procedures.

These self-interested cohorts have been extreme enough in the arguable harms that they do to have motivated the book:

Mark Scholz and Ralph H. Blum, Invasion of the Prostate Snatchers: No More Unnecessary Biopsies, Radical Treatment or Loss of Sexual Potency (Other Press, 2010)

Which the publisher (Other Press) summarized by saying that:

Every year almost a quarter of a million confused and frightened American men are tossed into a prostate cancer cauldron stirred by salespeople representing a multibillion-dollar industry.

In this flourishing business, the radical prostatectomy is still the most widely recommended treatment option.

Yet a recent and definitive study in the New England Journal of Medicine concluded that out of the fifty thousand prostate operations performed annually, more than forty thousand are unjustified.

But this is no surprise given that 99 percent of all doctors treating this disease are surgeons or radiation therapists. The appalling fact is that men are still being rushed into a major operation that rarely prolongs life and more than half the time leaves them impotent.

© 2010 Other Press, Invasion of the Prostate Snatchers: No More Unnecessary Biopsies, Radical Treatment or Loss of Sexual Potency, OtherPress.com (24 August 2010) (at first paragraph) (paragraph split)

PSA testing doubts took a long time to make it out into the light of day

What was medically and scientifically obvious to me, during a clinical urology rotation almost two decades ago, is only now making out into the public stage.

This is because the medical establishment, as a whole, has been reluctant to oppose financially motivated provider bias, except by issuing relatively mild presentations of data that should have dampened the rush to PSA test and “surgerize.”

I have previously written about this process:

here — PSA screening may not be routinely advisable except in high risk patients (15 September 2010)

here – PSA velocity of change not a good indicator absent risk factors (26 February 2011)

here — rate of serious biopsy-related prostate infections has risen (30 September 2011)

here — benefit of prostate cancer screening in low to average risk men is still uncertain (07 January 2012)

Today’s Annals of Internal Medicine article puts what should (but predictably will not) be a persuasive kabosh on indiscriminately wide PSA testing.

What the new guidelines say

What follows provides clarity in a medical screening arena that has long lacked it:

Guidance Statement 1:

ACP [American College of Physicians] recommends that clinicians inform men between the age of 50 and 69 years about the limited potential benefits and substantial harms of screening for prostate cancer.

ACP recommends that clinicians base the decision to screen for prostate cancer using the prostate-specific antigen test on the risk for prostate cancer, a discussion of the benefits and harms of screening, the patient's general health and life expectancy, and patient preferences.

ACP recommends that clinicians should not screen for prostate cancer using the prostate-specific antigen test in patients who do not express a clear preference for screening.

Guidance Statement 2:

ACP recommends that clinicians should not screen for prostate cancer using the prostate-specific antigen test in average-risk men under the age of 50 years, men over the age of 69 years, or men with a life expectancy of less than 10 to 15 years.

The moral? — Just because somebody thinks that you should be screened for some medical condition, don’t take their word for either (a) the screening necessity or (b) the reliability of the screening test that they are proposing

PSA testing is a good example of what happens, when:

(a) a well-intended screening device does not work (anywhere near as well) as advertised

and

(b) it sets the ball of too widely implemented and frequently harmful medical interventions rolling.

Being both medically and scientifically aware, I am distrustful of most of what the medical and pharmaceutical establishments trot out as their “new” best idea.

In virtually all cases, the scientific evidence supporting the “innovation” simply is not there, but significant elements in both establishments have, or quickly evolve, financial interests in making the often expensive and sometimes harmful quasi-quackery stick.

If we paid more attention to scientific proof in medicine (insofar as we can get it) and less to greed and wish-based illusions, we would be better off.

PeteFree.com

The Clinical Guidelines Committee of the American College of Physicians Indicates that for Many Men, the Potential Harms of Undergoing PSA Screening Outweigh its Unreliable Forecasting Value