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Oct
7

Prostate cancer screening – Is science winning?

The announcements this week that the United States Preventive Services Task Force has decided healthy men shouldn’t get the P.S.A. blood test is long overdue, but nonetheless very welcome news.
The test, which ostensibly screens for prostate cancer, is notoriously inaccurate, delivering a high rate of false positives and false negatives. And, men who get these tests have no greater chance of surviving the test than men who don’t.
Seventy percent of positive PSA tests are false positives; the patient does not have prostate cancer. Worse, these false positive tests often result in more tests and treatments that then result in impotence and incontinence and in some cases, premature death. According to the chair of the Task Force, “This test cannot tell the difference between cancers that will and will not affect a man during his natural lifetime. We need to find one that does.”
Over a twenty year period, about a million men got prostate surgery, radiation, or a combination as a result of a PSA test. Of those, about 5000 died soon after surgery, and from 10,000 to 70,000 suffered serious complications, and 200,000 to 300,000 were incontinent, impotent, or both. The dimension of the problem was starkly illustrated when the test’s developer called its widespread use “a public health disaster.”
There are passionate and dedicated folks who will argue vehemently that PSA tests are necessary and save lives. Unfortunately, many have become part of a campaign financed almost entirely by the pharmaceutical industry. I engaged in a dialogue for some time with one of them, and despite my best efforts, his conclusion is that the test saved his life and therefore others should get it as well.
It’s one thing to talk population health and an entirely different thing when one is talking about the health of one’s family or self. Unfortunately, well-meaning people often confuse the two – and this is what has led them to advocate for a test that is:
– costly (PSA tests range in cost from $70 – $200, plus the office visits, or about $3 billion a year just for the tests in the US);
– results in surgery that kills about five thousand men over a twenty year period and
– causes impotence and/or incontinence in 20% to 30% of patients
Some will argue that more recent developments in surgery have delivered better results – I’d say it’s too early to tell, which is why the Task Force used a database that would allow them to see effects over the long term.
What’s the net?
PSA testing is a great example of business masquerading as good medicine,
funded by businesses who profit from the test, who arguably, are partially responsible for the deaths and suffering of thousands of men.
It’s also a great lesson on why we need more science education in our schools, so so many of us would actually understand what a disaster the PSA test has become.


8 thoughts on “Prostate cancer screening – Is science winning?”

  1. This is a good message that needs to get out to the general male public and physicians.

  2. I have very mixed feelings about the PSA screening announcement and concerned about the tone of your message. An initial PSA was elevated in my husband at age 45 and 6mo. later further elevated. His symptom was frequency. A biopsy followed and confirmed his cancer. His surgery occurred at Johns Hopkins under world famous Dr. Patrick Walsh. Today, he has survived 14 years cancer free while a friend with the same cell type and very specific biopsy results who did the watchful waiting (advised he would die of something else first) is dead from the prostate cancer. I hope my message can save any man from an early unnecessary death. A PSA, like many other diagnostic tests, is one piece of the whole. So before you throw the PSA in the trash, please consider how you present your posting to men who will grab at any excuse not to investigate symptoms. Also, many physicians don’t realize that if they examine the prostate via rectal exam, it will falsely elevate the PSA drawn afterwards, and as Dr. Walsh teaches, if you feel the enlarged tumor via rectal exam, it is already spread outside the capsule of the prostate. Research is key to approaching best practices. I’m sure that carriers are only too glad to eliminate costs as well. If one has questions, they should consult their board certified urologist.

  3. The dilemma I had 10 years ago was a (slightly) elevated PSA, biopsy positive for cancer. Did I have slow or fast growing cancer? The urologists, including a friend who is board certified, all said surgery was the best and only choice because of the positive finding of cancer.
    10 years later I’m still left thinking, “Was it? Was it worth the inevitable and life altering side effects?

  4. Lynn – thanks for the comment.
    There’s no question some individuals have had successful treatment. However, the data clearly indicates that overall the negative consequences outweigh the potential benefits – both on an individual and population basis.
    Re your husband’s situation, you did not mention if he had the slow- or fast-growing type of prostate cancer. If it was the more common slow-growing type, the treatment likely had little impact on his survival. If it was not, there’s ample evidence the testing and procedure likely prolonged his life dramatically.
    I do not mean to discount your story, but rather to point out that the strength of the data is compelling. While your result was good, there are far more instances where the outcomes have been quite negative.

  5. I don’t see how you can reasonably conclude, based on the available evidence, that “the data clearly indicates that overall the negative consequences [of treatment and screening] outweigh the potential benefits, both on an individual and population basis”. Similarly, I don’t see how the Task Force can reasonably conclude that there is “moderate certainty” that the harms of screening outweigh the benefits.
    In my opinion, the best done study of prostate cancer screening is the European study. The initially published results were that screening reduced prostate cancer deaths by 20%, with a “number needed to treat” of 48 to prevent one prostate cancer death.
    However, this is after a mean follow-up time of 9 years after the experiment was begun. More recent analyses of the European data have looked at follow-up at 12 years after the experiment was begun, which is about as far as one can go and still have sufficient sample size. These more recent studies show a reduction of prostate cancer deaths in the screening group of over 50%, and a NNT of 18 to 1 after 12 years.
    Therefore, going from this European data, it would be reasonable to conclude that prostate cancer diagnoses revealed by screening reduce your chances of dying after 12 years by 5%. (This 12 year interval is since screening was begun; the interval after treatment was begun would be less.) This reduced risk must be weighed against a 30% increased risk of serious side-effects of treatment.
    While I think SOME men may conclude that the harms or negative consequences of treatment outweigh the potential benefits, I think OTHER men may reasonably conclude that the reduced risk of death outweighs the increased risk of serious side-effects.
    I think that the Task Force should upgrade its recommendation on PSA screening from a D to a C. A D says “don’t do screening, it clearly has harms greater than benefits.” A C says don’t do screening routinely, but rather a decision to do screening should be made on an individual basis. A C grade is much more consistent with the conflicting evidence on PSA screening.
    By the way, I am not a urologist. I am an economist who has recently had to face many of these decisions on an individual basis. I have tried to use my background in econometrics to become as familiar as possible with the relevant statistics on this issue.

  6. Tim – thanks for the comment.
    There’s no question the cost and potential negative consequences – driven by false positives and false negatives, far outweigh the potential benefits of a tiny percentage of fast-growing cancers discovered earlier than without PSA testing.
    The five percent decreased risk of death from prostate cancer (your number, which I would argue is optimistic) has to be balanced against the costs and problems amply described in the literature. Quite frankly, given a) the relative low risk of death from prostate cancer to begin with, and b) the pain, cost, psychological trauma, and potential adverse side effects of further screening and treatment, I feel very comfortable with my original statement.
    I’d also note that the European study on which your numbers were based is the most ‘favorable’ re PSA testing while several other studies (e/g/ VA, NEJM American study) show positive results were significantly lower and the negative consequences more dire. In fact, the NEJM American study showed that over a period of 7 to 10 years, screening did not reduce the death rate in men 55 and over.
    Joe

  7. Joe, a couple points:
    1. The European study might be the most “optimistic” study on the benefits of prostate cancer screening. But it is also arguably the best study, in that it has the largest sample size with the biggest differential between the sampling arm and control arm in percentage of men who actually underwent PSA screening. The American study had many men in the control arm who underwent PSA testing, so it is not a clean test of the effects of PSA screening.
    2. Perhaps it’s true for YOU that there’s no question that the cost and negative consequences of PSA testing outweigh the potential benefits. But many men may have different values than you do. They may view a 5% reduction in mortality as of great benefit, and may be willing to risk the side-effects.
    3. Given this difference in values, don’t you think it is reasonable for the Task Force to modify its recommendation from a D (no one should screen, harms outweigh benefits) to C (screening should not be done routinely, but should be individualized).

  8. Tim – thanks for the response.
    To address point 3,
    “For the USPSTF to recommend a service, the benefits of the service must outweigh the harms. The USPSTF focuses on maintenance of health and quality of life as the major benefits of clinical preventive services, and not simply the identification of disease.” (from their website)
    To move from a D to a C would, in their (and my) estimation violate the classification of a D – as harms do truly outweigh benefits. This isn’t a question of my values v others’ values, it’s a question of science – and the Task Force’s careful, methodical, painstaking approach to their decision and careful weighing of the evidence is solid science at its best.
    I’d note that for some, harms could never outweigh the benefits and therefore may get many tests at high cost and some level of pain and discomfort. Those individuals can always get whatever test they want, as that’s their decision. But for policy purposes, there’s no question PSA tests do far more harm than provide benefit.

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Joe Paduda is the principal of Health Strategy Associates

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