“Watchful Waiting” vs. “Precautionary Principle”

Watchful Waiting = Do nothing, even though it may be a good idea to do something, because it’s difficult to justify doing something when institutional third-party payers who evaluate everything in terms of population average costs and benefits rather than your cost and your benefit are making the decisions.

Precautionary Principle = Take extreme measures, even though it may be a good idea to do nothing, because it’s difficult to justify doing nothing when activists who evaluate everything in terms of hypothetical worst cases rather than probability weighted costs and benefits are making the decisions.

The question that always matters most is “Who decides?”. Answer it and you can usually predict what the answers to the other questions will be.

9 thoughts on ““Watchful Waiting” vs. “Precautionary Principle””

  1. The sad thing is that this is a perfect chance to actually educate people about the real tradeoffs involved in screening, and in stead we will just get a lot of shouting and posturing (the mamogram dustup being a similar case).

    PSA screening is relatively cheap as a test, but worthless as a diagnosis tool. Because it is incapable of distinguishing between a benign and malignant tumor, a postive PSA result requires follow-up testing and treatment to determine if the cancer present actually requires treatment. It is the follow-up that is expensive, prone to complications (impotence) and is of questionable value to the patient (even discounting the costs). Any test which has a singificant number of false postives (which the PSA does, as many cancers detected are no real risk to the patient) is going to be of questionably utility if the follow-up testing/treatment is prone to complications.

    The hope with PSA screening was that it would be a tool that could cheaply determine if cancer was present and then allow for early treatment that would be more effective. Unfortunately, experience has shown this is not the case. A positive PSA result does not reliably indicate a dangerous cancer, and the treatment options even if it is are not improved by the earlier detection. So you get little improvement in the dangerous cases and lots of unpleasant side effects in the false positives. (personal note : my father died of prostate cancer, 4 years after his inital treatment for it, and 3 years after his diagnosis with Alzheimer’s – after which he said that if he’d known about the Alzheimer’s he’d have skipped the cancer treatments)

    The real problem with prostate cancer is that most men who have it will die from some other cause first anyway. For them, any treatment is a waste of money and a negative outcome from a quality of life perspective. A high PSA result for a 60 year old man basically says “you have prostate cancer. It will probably kill you sometime between now and your 90th birthday, assuming nothing else does. We have no way to tell when. Treatment will be painful, has a real risk of impotence. The most likely outcome in the case where it is likely to kill you in the next 10 years is only extending your life a couple of years vs leaving it untreated”. Personally, I’d rather we spent the time and resources on coming up with a better test and better treatment options.

  2. Phwest,

    Thanks. Your argument makes a lot of sense WRT treatment. But surely 1) a biopsy is a good idea in many cases where a patient’s PSA increases from one measurement to the next, and 2) it should be the patient rather than third parties who gets to authorize the biopsy and to decide what if anything to do next.

  3. The PSA test, unless it is very high, is usually one of a series and the trend is what makes the determination. Some judgement is required and here is where we have lost a lot of the benefit of the primary care physician. For example, impotence may be a major or minor consideration depending on the pre-treatment situation.

  4. Tatyana: My Doctor said pretty much what Dr. Kennedy said. PSA is a blood test, much less painful than digital palpation, so I just do what the Doctor says.

  5. Richard: good.
    Phwest: OK, PSA as a preliminary indicator might be a bad choice. Is there other test that is a good one?
    Or is it the same situation as with routine mammogram: it is not 100% reliable, it is only done once a year, leaving certain percentage of fast-growing cancers undetected until is too late, it is not by itself a definite indicator, etc.?

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