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Private clinics should stop offering whole body computed tomography scans to people who are without symptoms, because of a lack of evidence that the benefits outweigh the risks, the UK’s radiation watchdog has said.
In its report the Committee on Medical Aspects of Radiation in the Environment also says that computed tomography should not be used to check for lung cancer, because there is no evidence of benefit. In addition, anyone who presents with any symptoms that may indicate a serious condition should be referred back to their GP rather than be offered a scan.
The committee is concerned about the increasing amount of radiation that people are being exposed to. It estimates that in the United Kingdom 15% of an individual’s exposure comes from medical sources; and although the average dose of radiation exposure was falling in the 1990s, it is likely to increase in the future as technology becomes more sophisticated.
The report says that although the risk of radiation exposure from computed tomography is low, people need to be aware that it exists. A typical scan is associated with a risk of 1 in 2000 of getting fatal cancer in a lifetime, whereas the natural risk of getting cancer is 1 in 4. It says that if 100000 people had a scan every five years between the ages of 40 and 70, an additional 240 deaths from cancer would result.
Alex Elliott, chairman of the committee, said that it was not known how many people in the UK have had private medical scans. But new data just published in the United States indicated that between 1% and 2% of cancers there are due to medical exposure to radiation. “[This is] not an inconsequential problem,” said Professor Elliott.
Besides exposure to radiation, people can become unnecessarily alarmed and anxious if a scan reveals something that turns out to be harmless, says the committee. They may also be subjected to a number of further tests, many of which themselves carry risks and the cost of which is picked up by the NHS.
The report calls for a stop to the use of computed tomography to assess spinal conditions, osteoporosis, and body fat, as more appropriate tests are available with a lower risk of radiological exposure.
However, some computed tomography scans are justified, it says. People at high risk of heart disease may benefit from a scan to assess coronary artery calcification, although this should not be done more than once every three years. Computed tomography of the colon also has the potential to detect small lesions, although this should not be done in asymptomatic people aged under 50 years, the report recommends.
The committee calls for a review of how private clinics are regulated, because private computed tomography services are exempt from some of the regulations that apply to the NHS, as they don’t involve treatment.
Lifescan, the UK’s biggest private provider of organ specific screening services, has welcomed most of the report’s recommendations. But it says the assertion that private scanning costs the NHS because of investigations of false negative results is “highly speculative.”
John Giles, consultant radiologist at the Conquest Hospital, St Leonards, East Sussex, and clinical director at Lifescan, said, “We confidently estimate that we have saved the lives of over 2000 people who were identified with a potential life threatening disease and able to receive early and more effective treatment.”
The Impact of Personally Initiated X-ray Computed Tomography Scanning for the Health Assessment of Asymptomatic Individuals is available at www.comare.org.uk.