Is difficult—but many misconceptions need to be undone

“By offering screening to 250 000 we have helped a few, harmed thousands, disappointed many, used £1.5m each year, and kept a few lawyers in work.”1 This conclusion, by one of the authors of a report on cervical screening in Bristol, illustrates that screening, like most medical interventions, has harms as well as benefits. All the more reason therefore to ensure that patients undergoing screening are fully aware of both the benefits and the harms. Yet there are many barriers to seeking truly informed consent, and we know surprisingly little about effective ways of doing so.

The detrimental side effects of screening include anxiety, false alarms, false reassurance, unnecessary biopsies, overdiagnosis, and overtreatment. Some people have a disease detected on screening, receive treatment, yet still develop recurrent disease: we have made no real difference to their destiny, just prolonged the period they are aware of their disease. False positive results can cause major distress as well as prompting further investigations, often invasive, before the patient can be cleared. A recent study of mammography in the United Kingdom found that anxiety in women requiring further investigation because they were false positive on initial screening was still significantly higher 11 months after their recall appointment than in women who received negative results …