In recent years medicine has sought to extend its influence beyond the sick by diagnosing, in the vastly greater numbers of the healthy, diseases that they do not know they have – and then treating them. This takes several forms: one much favoured by the pharmaceutical industry is to claim that the average blood pressure or cholesterol level is ‘too high’, with the result that millions of people now take drugs for life to lower them. Then there is screening in anticipation of detecting cancer of the breast or cervix early enough for it to be treatable. This enterprise is not entirely futile but is costly, logistically complex and not without the hazards of generating much anxiety and adverse side effects.

Invasion of the Prostate Snatchers tells the story of how this enterprise can go badly wrong. It is a story in which all the sins of medicine – its facade of knowledge, refusal to acknowledge error, moral blindness and cupidity – have resulted in a medical catastrophe of