19 March 2009

Good News for Your Prostate

Some very important research on prostate cancer screening and treatment was just concluded and published. NYT has a good writeup.

The fact is that if you get prostate cancer it will kill you, or not, at whatever stage it is diagnosed. Say a man has a PSA test today and it comes back positive.

    It leads to a biopsy that reveals he has prostate cancer, and he is treated for it. There is a one in 50 chance that, in 2019 or later, he will be spared death from a cancer that would otherwise have killed him. And there is a 49 in 50 chance that he will have been treated unnecessarily for a cancer that was never a threat to his life. Prostate cancer treatment can result in impotence and incontinence when surgery is used to destroy the prostate, and, at times, painful defecation or chronic diarrhea when the treatment is radiation.
So, each year more than 180,000 men receive a diagnosis of prostate cancer, but of those only 3600 will truly benefit from the traumatic treatment. And there is no way to tell who those are.

The good news, then, is that it now appears pointless to get screened and treated for prostate cancer. You may be that one in fifty men who will benefit. But the odds are not high and the downside risks are very substantial.

And in fact, these studies are also significant for women with respect to mammograms and breast cancer:

    Screening is not only an issue in prostate cancer. If the European study is correct, mammography has about the same benefit as the PSA test, said Dr. Michael B. Barry, a prostate cancer researcher at Massachusetts General Hospital who wrote an editorial accompanying the papers. But prostate cancers often are less dangerous than breast cancers, so screening and subsequent therapy can result in more harm. With mammography, about 10 women receive a diagnosis and needless treatment for breast cancer to prevent one death. With both cancers, researchers say they badly need a way to distinguish tumors that would be deadly without treatment from those that would not.

Update: There is a follow-up article in the NYT on the results of these studies that is a little more nuanced in interpreting them (for another counterpoint, see also here). Clearly further research may modify their conclusions. But it also summarizes the present results in clear and simple terms: "The [PSA] test is about 50 times more likely to ruin your life than it is to save your life."

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