[Is prevention better than healing?]

Preventive and screening interventions have been met with great enthusiasm. This is due to a widespread misunderstanding of what prevention can do and what it cannot do. Initiatives for prevention or early diagnosis of disease are almost always considered beneficial. Meanwhile, however, there are many impressive examples of detrimental failures of such initiatives documented by large high-quality randomised controlled trials (RCTs). These include treatment with vitamin pills to prevent cancer or cardiovascular disease or treatment of healthy women with sexual hormones which has finally turned out to be one of the biggest scandals in medicine. Systematic self-examination of the breast to detect breast cancer early does more harm than good. Most dogmas of the modern so-called healthy diet are not supported by several recently published high-quality RCTs. On the other hand, many of the promoted prevention initiatives lack evidence from high-quality RCTs such as health checks, rectal examination, screening for renal disease or diabetes, screening for colorectal cancer by coloscopy, for prostate cancer or skin cancer. Even if effective, most screening programmes will benefit only a few but harm many more, though. Harm is due to overdiagnosis and overtreatment as well as to side effects related to the investigation itself. This includes psychological and other distress related to work-up of false test results. All prevention programmes have to undergo sound scientific evaluation before they can be recommended or implemented. Ethical guidelines ask for complete, objective, unbiased, evidence-based and understandable information for potential participants of prevention programmes. Rarely is such information provided or even available. Non-participation is an explicit option for most preventive programmes and must not be penalised.