Cancer screening is plagued by dissonance

Cancer screening is plagued by dissonanceLast year, the USPSTF was poised to meet regarding its prostate cancer screening guidelines.

According the Kenny Lin, a physician who was with the Task Force at the time, the meeting was cancelled for political reasons. He points us to a New York Times story on the dueling narratives of prostate cancer screening.

It’s a topic that often appears here on KevinMD.com, and it seems to have endless life.

On one side are the specialty-based recommendations that support PSA screening, backed by emotional anecdotes from prostate cancer survivors.

On the other are the evidence-based recommendations, like the ones from the USPSTF. As the Times story notes, this camp “makes a less emotionally satisfying argument: on balance, scientific studies do not support the claim that screening healthy men saves lives. Screening … can lead healthy men into a cascade of further testing and treatments that end up injuring or even killing them.”

This is a familiar dissonance that plagues the cancer screening debate.

Cancer screening is generally presented only in a positive light in mainstream media. “Early detection saves lives,” is what we often hear. But the reality is more nuanced, and unfortunately, isn’t prone to pat soundbites or inspirational ad campaigns.

Consider the following metaphor that illustrates this phenomenon, starkly told by David Newman, a director of clinical research at Mount Sinai School of Medicine in Manhattan:

“Imagine you are one of 100 men in a room,” [Newman] says. “Seventeen of you will be diagnosed with prostate cancer, and three are destined to die from it. But nobody knows which ones.” Now imagine there is a man wearing a white coat on the other side of the door. In his hand are 17 pills, one of which will save the life of one of the men with prostate cancer. “You’d probably want to invite him into the room to deliver the pill, wouldn’t you?” Newman says.

Statistics for the effects of P.S.A. testing are often represented this way — only in terms of possible benefit. But Newman says that to completely convey the P.S.A. screening story, you have to extend the metaphor. After handing out the pills, the man in the white coat randomly shoots one of the 17 men dead. Then he shoots 10 more in the groin, leaving them impotent or incontinent.

Newman pauses. “Now would you open that door?” He argues that the only way to measure any screening test or treatment accurately is to examine overall mortality. That means researchers must look not just at the number of deaths from the disease but also at the number of deaths caused by treatment.

The potential risks of cancer screening needs to be presented in the same light as its benefits. That includes the possibility of harm from increasingly invasive testing, along with complications from treatment.

Only when this complete picture is presented in the media can patients make a better informed decision.

 is an internal medicine physician and on the Board of Contributors at USA Today.  He is founder and editor of KevinMD.com, also on FacebookTwitterGoogle+, and LinkedIn.

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  • http://www.facebook.com/profile.php?id=553105686 Leslie Edwards

    As a patient, I have noticed the surge in media about the flipside of screening (for various things). More of us are going to our doctors’ offices expecting informed consent. If someone tells me that there are no potential downsides to a test, I become very skeptical and start to tune out the rest of doctor’s advice.

  • http://twitter.com/DoctorPullen Edward Pullen

    This whole issue and the issues of overdiagnosis, real risks of screening, and need for non-emotional,honest, evidence based USPSTF recommendations is huge.  How much this plays a role in defensive medicine, costs related, etc. is hard to overestimate.  

  • Anonymous

    My father died of prostate cancer on August 13th, after a five-year struggle. You can imagine which side of the argument I come down on. What the media needs to emphasize is that prostate cancer can be indolent or it can be very aggressive, and some of us learn too late that it gallops through our families, leaving Gleason 9 disease in the future of every person with a Y chromosome. Today I met a woman whose husband comes from a similar family, and she will be dragging him in for a PSA test. This is not the same disease in every patient, and the same recommendation does not serve all equally. Doctors don’t treat cohorts; they treat individuals.

  • Anonymous

    Couldn’t agree more, but at lest you’re permitted to have the discussion in prostate screening. Try refusing cervical and breast cancer screening – we’re just expected to comply like sheep and many doctors in the States and Canada use coercion to force women into cancer screening. One common tactic – if you want the birth control pill you have to agree to not only pap testing, but usually over-screening or inappropriate screening, plus a pelvic exam and breast exam. None of those things have anything to do with the Pill – cancer screening is elective and ethically and legally requires our informed consent, bimanual pelvic and breast exams are of poor clinical value in asymptomatic women and carry risk. Our doctors don’t recommend them – I’d never permit them anyway.
    I made informed decisions not to have cancer screening and that meant doing my own research and finding articles written by the few doctors who respect our right to make an informed decision, and that means having access to ALL of the facts.

    The way medicine is practiced in the States, you’re much more likely to be harmed by cancer screening. At least in countries like Finland, the UK and the Netherlands there is some consideration for the majority of people who’ll never benefit from screening – some attempt is made to minimize false positives, over-treatment and over-diagnosis. The UK is fortunate to have many outspoken advocates for informed consent – Dr Raffle, Prof Baum, Hazel Thornton and others.
    There is still little respect for informed consent in women’s cancer screening…screening is still largely “done” to women. Doctors or the govt make the decisions and accept risk on behalf of women. Our doctors even get target payments for pap tests – most women are unaware of this potential conflict of interest. It seems anything goes to protect the program and its target.

    I noticed my husband when he turned 50 was provided with an A4 sheet of paper listing the risks and benefits of prostate screening (and it was a lot more than a sales pitch for the test) and the doctor stressed it should be my husband’s decision.
    I couldn’t help but contrast that with the attitude most women receive when screening is mentioned…you MUST, SHOULD or WILL have this test and most receive no information or no real and unbiased information.
    I gave up waiting for honest and complete information and did my own research – it’s the only way to make an informed decision – IMO, screening is largely controlled by profits, politics and vested interests and has little to do with our health. Breast Screen Aust. are chasing a screening target of 70% of women aged 50-69 and recently announced on the News that women should have confidence in screening after research from Sweden showed lower mortality for screened women in the long term. She omitted to mention a later study that showed the fall in the death rate was about better treatments, and not screening. This selective presentation of research is not only unethical, it shows a reckless disregard for our health and rights – they’re protecting the program and target, not us.
    Of course, not one Aussie doctor has stepped forward to warn women of this critical omission. We have no real advocates for informed consent for women in this country, there are those who’ll speak out in medical journals, but nowhere women might actually see or hear it. Our programs basically operate outside the Law (informed consent) and ethical standards (honesty, professional standards, conflict of interest) and no one seems to care.

    • Anonymous

      I agree with much that you say.

      HOWEVER, you have to realize that docs in the US get sued and lose big time for failure to diagnosis when a patient makes an informed decision not to screen and subsequently develops cancer. 

      • Hexanchus t

        Which needs to be fixed.

        With the right to make decisions comes the responsibility for the consequences of those decisions. A patient’s documented informed decision to decline screening should be a prima facie defense against malpractice for failure to diagnose. This assumes, of course, that the patient was given full, unbiased information in a format easily understood by a lay person, including that if they decline screening and subsequently develop a related cancer, the diagnosis could come later and the prognosis adversely affected – even have them sign a statement to that effect (liability waiver).

        It’s not a complex fix. Ultimately we really need to change from a “standard of care” model to “evidence based”,  but getting the current bunch of idiots we have in congress to get their collective head out of their a$$ and actually do something is whole other story….

        Elizabeth makes some excellent points, both about the relative value of the tests/exams and lack of informed consent. I believe that the major driving forces are financial. Certainly the threat of a tort claim, as you suggested, is a concern. The other major factor, IMHO, is that pap testing and the subsequent followup procedures and treatment they generate (the majority of which is unnecessary) is a multibillion dollar a year industry. Start cutting back on that and somebody is going to take the financial hit, and those that are affected are going to squawk – witness the outcry in 2009 when USPSTF changed the mammogram recommendations, and the one we’re about to see over the just released recommendations on PSA testing.

        When in doubt, follow the money…….

  • elizabeth52

    I just read a draft recommendation by the United States Preventive Services Task Force, due for official release next week, NOT to recommend PSA testing for healthy men (symptom-free) – they believe overall it does not save lives and often leads to painful, unnecessary treatments and biopsies that can leave men with impotence or incontinence.
    http://www.nytimes.com/2011/10/07/health/07prostate.html

  • http://investinginkids.net/ Tim Bartik

    The trouble with David Newman’s story is that in fact, the existing studies do NOT have sufficient sample size to either prove or disprove the effects on overall mortality that one might expect from PSA screening.

    Just go and LOOK at the standard errors in the European study. And then simply calculate what the effects on overall mortality would be if PSA screening’s estimated effects on prostate cancer mortality were 100% reflected in overall mortality. You will see that the overall mortality confidence intervals are too wide to tell much of anything about whether PSA screening reduces overall mortality.

    This is a basic statistical point that seems to be missed by many of those engaged in this debate. Because prostate cancer mortality is a much rarer event than overall mortality in this sample of older men, the “signal” of any effect on prostate cancer mortality is lost when we instead focus on overall mortality. Or in other words, the standard error of an estimated sample proportion is far higher for an event with an overall probability of 20% (overall mortality in this group over 10 years) than for an event with an overall probability of perhaps 0.8% (prostate cancer specific mortality in this group over 10 years). All the existing screening studies are “under-powered” to detect effects on overall mortality, and they should not be used to do so.

    One response is that if PSA screening’s effects on overall mortality are only 0.1% or so after 9 years, then it can’t be worthwhile. But as most of the benefits and costs of PSA screening are due to the benefits and costs of treatment, the relevant number is not the “number needed to screen” to reduce one prostate cancer death, but the “number needed to treat” to reduce one prostate cancer death. What we should be debating is what is the NNT, as judged by estimated effects on prostate cancer specific mortality, which is what we can measure effects on with sufficient precision.

     David Newman’s story is more relevant if we exclude the guy who is shot dead. The essential tradeoff is between the reduced deaths due to treatment versus the serious side effects of treatment. What we need to consider is the NNT and also the proportion of those treated with serious side-effects. Then men can reach their own decisions on how to manage this tradeoff.