Further to my two recent posts about prostate cancer screening, in this piece in the LA Times H. Gilbert Welch, professor of medicine at the Dartmouth Institute of Health Policy and Clinical Practice, brings into clear focus the contrasting results of the two studies that have lately had press coverage. Welch writes that prostate cancer screening is a challenging issue because, while it may save some lives, 'it will harm many others along the way'. He continues:
Two weeks ago, we learned more. The results of two large, randomized trials of prostate cancer screening were published. The studies represented an enormous research effort: almost 20 years of work, involving more than a quarter of a million men and many millions of dollars.
Yet there is still some uncertainty whether screening saves any lives. The European study said yes; the U.S. study said no. That in itself tells you something: If there is a benefit, it is undoubtedly small. In contrast, researchers in the 1960s were able to convincingly demonstrate the benefit of treating very high blood pressure by studying about 150 men over a two-year period. Why were they able to do this with so few men so quickly? Because the benefit was huge.
I believe there probably is a benefit to prostate cancer screening. But it is accompanied by a substantial human cost. Let's assume the European study is right. Its data give us some idea of the magnitude of the trade-off: For every man who avoids a prostate cancer death, about 50 are treated needlessly (some of my colleagues might say the number is closer to 30, others might say it's closer to 100).
Being 50 times more likely to be diagnosed and treated needlessly than being the one man who avoids a prostate cancer death doesn't strike me as a good gamble.
Welch's conclusion is to the point:
There is no imperative to be screened, or not screened, for prostate cancer. The only imperative is that men be informed about the consequences of either choice.