20 September 2003
The value of full body CT (computed tomography) scans as a screening tool has been questioned following Australian research suggesting that lung cancer, colon polyps and coronary artery atheroma are the only realistic candidates for screening, and only in targeted populations.
(Note: a screening tool aims to detect disease in healthy people who have no symptoms of illness. This is in contrast to a diagnostic tool which aims to find the cause of illness in a person who is unwell. A CT scan is a specialised form of imaging that draws together multiple X-ray images to form a 2-dimensional cross-sectional image. A CT scan can be used as either a screening tool or as a diagnostic tool, depending on the context.)
All cancers other than those listed above have such relatively low incidence, even in elderly people, that they are unlikely to be identified at an early stage with an unenhanced scan, said study author Dr Michael Jones, a member of the Royal Australian and New Zealand College of Radiologists' (RANZCR) diagnostic economics committee.
In a paper presented to the RANZCR annual scientific meeting in Brisbane this week, Dr Jones explained that the study was about the cost-effectiveness of screening, and did not address the issue of clinical desirability.
To be useful, CT screening must look for cancers with a high incidence and those unlikely to be confounded by benign lesions and cysts.
Based on incidence, mortality (death rate) and detectability, the only potentially cost-effective candidates for CT screening would be lung cancer in female smokers aged 60 years and older and in male smokers aged 50 years and older; colon polyps in the 50 years and older group; and coronary artery calcium scores (to indicate the presence of calcified plaques in the walls of the coronary arteries) in the 50 years and older group, Dr Jones said.
Patients in NSW now need a referral from an independent doctor before having a full body CT scan.
Last Reviewed: 22 September 2003