One of the reasons given for the so-called advances in the war against cancer is that doctors are now screening for cancer, and so are able to detect and treat it earlier. This belief has become so entrenched in the medical mind that no amount of contrary evidence appears able to shift it – not even the fact that for every single type of cancer, screening doesn’t work.
Take the story of the conversion of Professor Michael Baum, a leading British breast-cancer expert and one of the major forces behind the establishment of NHS breast screening in 1987. At first, he was pleased with his creation but, over the years, he has become increasingly concerned. A hard look at the evidence over the last 15 years has convinced him that the supposed benefits of screening are largely a myth. ‘It’s a common misconception that early detection is of benefit and implies reduced mortality,’ he says (BMJ, 2003; 327: 101-3). Indeed, Baum now believes that screening may actually cost lives by leading to unnecessary biopsies or surgery (Int J Epidemiol, 2004; 33: 66-7).
It’s the same with prostate cancer. Here, the prostate-specific antigen (PSA) test has been touted as an infallible marker of the disease. But experience has shown it to be worse than no test at all. Not only is there ‘a lack of credible evidence’ that PSA screening saves lives, but some experts say that screening has harmed and even killed people as a result of the unnecessary treatment it leads to. A Yale University report spells it out in cold clinical terms: ‘. . . population-based screening (with subsequent diagnosis and treatment in many men) can be associated with considerable morbidity and mortality in the context of a disease that is often not fatal’ (J Sci Am, 2000; 6 Suppl 2: S188-92).