Science

Is It Better To Know, Or Not To Know?

Sometimes you are better off knowing less rather than knowing more. At least this is the reasoning of one panel of medical experts in the United States.

More than 30,000 men are estimated to have died of prostate cancer in the U.S. in 2010, with over 200,000 receiving a positive diagnosis. According to the NY Times, autopsy studies reveal that more than a third of men between the ages of 40 and 60 have prostate cancer.

It turns out that it is relatively easy to find out whether a man is at an elevated risk of cancer of the prostate (which is of course a totally different matter from testing whether he has cancer). A simple blood test allows one to measure the level of prostate-specific antigens (PSA). Higher than normal PSA levels — that is to say, crucially, higher relative to a person's own baseline normal — makes it more likely, although by no means certain, that one has prostate cancer.

So shouldn't you have the test?

The panel says no, and their logic is impeccable.

Suppose you have the PSA test and your levels are elevated. You have learned that you are at a higher risk of prostate cancer, a disease that might kill you. What do you do now? Here's where it gets tricky.

Remember, many prostate cancers are very slow growing; you might have the disease, but it might never affect your health. And cancer is not the only cause of elevated PSA; so you might have a false positive. Of course it might also turn out that you discover that you've got treatable cancer and the treatments may save your life. Or it may be that you won't be able to treat the disease; maybe it's too far along and is going to kill you whatever you do.

The problem is that the further diagnostic tests to confirm a cancer diagnosis, unlike the initial PSA blood test, are both invasive and dangerous, as are the treatments themselves.

So you might think that the moral of the story ought to be: use great care in deciding, on the basis of a PSA test, to pursue further tests and treatments, for the latter may be worse than the disease.

But that's not the recommendation of the panel.

They say: don't get the PSA test in the first place. Why? Presumably because they feel that most men, and their doctors, knowing that they are at elevated risk, will feel compelled to take additional steps. And indeed, this is precisely why so many prostate cancer groups recommend that men get the PSA test ever year — so that they can act if their levels rise.

I said the the panel's logic is impeccable. It is. But what's striking is that it relies on the premise that men with high PSA, even in consultation with their doctors, won't be able to make smart choices about what to do next.

Are they right about this?

Maybe. Perhaps they know that — for most men — it's impossible to stop the medical-industrial machine once you've jumped on board. Or that anxiety will force men to act irrationally.

But is this really something a panel of doctors can decide?


You can keep up with more of what Alva Noë is thinking on Facebook and Twitter.

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