Screening is one of the golden means of medicine. Regular screening can help detect in their earliest stages cancers that might otherwise prove fatal - or so the script reads.
Unfortunately, it's not that simple. Screening sometimes produces false positives - where a cancer is wrongly detected, thus putting the person through unnecessary stress - while mammograms have spread tumours.
A new study has put into perspective cervical screening. Researchers have found that 10,000 women need to be screened for 35 years - at enormous expense and strain to the medical system - to prevent just one death from cervical cancer. By comparison, a nurse performing just 200 tests each year would have prevented a death from cervical cancer once every 38 years.
For that one prevented death, 152 women will have gone through the unnecessary stress of a false positive, while a further 79 would be referred for further investigation because a benign abnormality had been detected.
Not only is this a waste of valuable medical resource, the screening programme also increases the risks of harm caused by medical intervention, say researchers at the Avon Health Authority.
(Source: British Medical Journal, 2003; 326: 901-4).