The emergence of whole-body computed tomography (WBCT) as a tool for assessing a person's overall health seems, on the face of it, to offer many benefits. In many countries, there has been a concerted effort, often led by government agencies, to encourage people to take more responsibility for their own health, and WBCT may seem like a good place for them to start.
The problem, however, is that such scans can cause more problems than they solve. Rather than reducing the burden on healthcare services, WBCT can place increased pressure on medical professionals and cause unnecessary distress to patients.
In the US and in Europe, many private companies have emerged that offer WBCT services, and often these are aggressively marketed and play on people's health fears.
CT, also called computerised axial tomography (CAT), scanning, is presented as a proactive or preventative measure for apparently healthy individuals who have no symptoms of disease. However, many radiologists are uneasy with this situation.
Dr Jonathan Breslau, president elect of the California chapter of the American College of Radiology, says: "We find that doctors often report that, with WBCT, they find a lot of pseudo-disease, which ultimately leads to many unnecessary procedures being carried out. Instances of pseudo-disease are far more prevalent than unexpected cancers.
"WBCT findings are often uncertain, and you have to consider who pays for the biopsies and imaging tests that may be performed unnecessarily as a result of these scans. The use of WBCT in healthcare has got out of control. It is finding too many things that don"t need to be discovered."
The problem of paying for follow-up procedures is particularly acute in the UK, where the cost is borne by the National Health Service (NHS). Currently, the UK is a few years behind the US, so the NHS and healthcare professionals are watching the rapid rise in the popularity of WBCTs with interest and some concern
The companies offering WBCT for a fee are keen to point out its apparent advantages, but official comment from healthcare professionals states that their claims are not supported by any hard data. The US Food and Drug Administration (FDA) clearly states that there is no sound rationale for carrying out these scans.
Currently, there is no FDA approval for self-referred WBCT screening. In fact, the agency states that any company marketing WBCT services as "approved", "cleared" or "certified" by the FDA is guilty of misrepresentation.
The FDA has never approved, cleared or certified any CT system specifically for the screening or individuals without symptoms, as no manufacturer has demonstrated a CT scanner that can effectively screen for any disease or condition.
Furthermore, the FDA notes that WBCT scan results can provide false reassurance or lead to unnecessary follow-up procedures, in many cases involving invasive procedures and the additional surgical risks they carry.
The agency's official stance on WBCT is that it is unlikely that CT screening will benefit an individual lacking signs or symptoms of disease by detecting a serious disease early enough to treat it and alter the outcome significantly.
Research studies are underway to test the potential benefits of CT, they focus mainly on groups with a high-risk profile for specific diseases. They are not testing the validity of the claims made in support of self-referred WBCT scans, but focus on limited portions of the body.
The FDA's conclusions on WBCT are supported by recent research in the UK, where the government engaged the Committee on Medical Aspects of Radiation in the Environment (COMARE) to examine the available data and inform official policy.
Dr Gill Markham vice-president of The Royal College of Radiologists, says: "The COMARE report states that there is no justification for WBCT, although there is a case for screening for specific problems, such as cardiac or colonic conditions, if there is a family history of such disease.
In December 2007, the Committee on Medical Aspects of Radiation in the Environment (COMARE) set out to examine the scanning of asymptomatic individuals using computed CT X-ray screening and identify the implications for public health.
COMARE was established in the UK in 1985 with a view to assessing and advising government agencies on the health implications of man-made radiation.
The report focused not only on the detrimental effects of radiation from WBCT scans, but also on the psychological and physical effects of WBCTs on patients, as well as the economic impact on the UK's National Health Service.
Chief among COMARE's recommendations is that commercial CT services should be further regulated. It also urges greater provision of detailed information to clients regarding radiation doses and the possibility of false negative and false positive results.
Furthermore, it notes that if commercial CT services are to have a place in healthcare, the providers of the scans should ensure that they have well-developed and confidential mechanisms for integrating examination results into an established care pathway, and that their data should be in a format compatible with NHS IT programmes.
The COMARE report states firmly that it is not possible to optimise exposure parameters for whole-body CT scans, and strongly recommends that such services be discontinued for asymptomatic individuals.
The study also examined the scanning of three specific anatomical regions and concluded that there is no evidence that CT scanning for lung conditions is of any benefit, although cardiac scans can help improve cardiovascular risk assessment, and colonography can detect small lesions. However, the report states that, even where there is a benefit, scans should only be carried out for a few asymptomatic individuals.
Perhaps the main concern for healthcare professionals is the fact that those subjecting themselves to whole body scans are likely to be receiving unnecessary doses of radiation. The additional radiation to which patients are exposed slightly increases their risk of cancer. In normal diagnostic or therapeutic CT scans, this small risk is vastly outweighed by the benefit in terms of meeting their medical needs, but there seems to be no such justification for self-referred WBCT scans.
"We are very concerned about the radiation dose involved, particularly as the findings are often sub-optimal – there are different technicalities and specific settings required to look for problems in the lungs or the kidneys, for example," says Markham. "People forget about the dangers of radiation, which persist even though doses are lower now than in the past."
For patients, the most distressing aspect of the WBCT scan trend is that false positives regularly show up. Their lack of specificity means that the scan may suggest the presence of 'something', but not indicate what it might be. Once seen, however, further exploration is required, causing emotional distress that is usually unnecessary.
"The scanner finds too many things," says Breslau. "For instance, there are often lots of small nodules on the lungs, and non-specific masses on the adrenal glands, liver and kidney. When you find one, you have to do multiple studies over many years to ensure that they don't grow. This kind of detection of non-disease is a big drawback for WBCT."
Markham says: "We get a lot of letters about the emotional distress caused by WBCT, which often causes people to worry for no reason. There are a few positives, but they are very unusual. This is one of the reasons the COMARE report recommends regulation of the sector."
Some healthcare professionals go as far as to say that unnecessary the surgical procedures that can result from false-positive WBCT scans are tantamount to causing injury to patients, which goes against the fundamental ethical foundation of the medical profession. It can also be argued that there is a downside to getting the all-clear from a whole-body scan. Such results may discourage some people from taking better care of their health in the future.
CONSENSUS ON CAUTION
The doubts over WBCT shared among healthcare professionals in the UK and the US show that there is little to support the claims of the companies offering WBCT scans. Of course, there are stories of disease being found through WBCT, but medical practitioners do not feel these are common enough to justify the cost of WBCT to public health systems or the dangers posed by unnecessary exposure to radiation.
It seems that the official consensus in the UK and in the US is helping get the message across to the general public. At one time, it was estimated that three in every four Americans were signing up for whole body scans, but Breslau is happy to note that the trend for self-referral is reversing.
"In the US, it was a fad, and it is waning in popularity," says Breslau. "This can only be a good thing, as organised radiology does not want to see it grow. Each time a person has a WBCT, they are measurably increasing their risk of cancer, and there is no obvious benefit." He believes that all of the companies in the US that specialised solely in WBCT have gone out of business.
"If a patient came to me asking for a whole-body scan, I would try to talk him out of it," adds Breslau. "He would not be able to get it at any of our imaging centres, but he would be able to go to any number of places where they will do it if you write out the cheque."
Markham takes a similar line. "I would never have a whole body scan and no-one I know in the medical profession would," she says.
She adds that we must look out for companies offering WBCT in new guises. She notes that some companies, probably to dissociate themselves from the COMARE report and the negative publicity about WBCT, now offer "multi-organ" scans. These, she says, are whole body scans masquerading as something else, and they still lack the specificity she feels is so important.
Both she and Breslau believe it is important to stress that specifically targeted screening programmes can be enormously beneficial.
For example, the success of mammography screening programmes in detecting breast cancer in its early stages has been remarkable.
"There is an emphasis in health education and publicity material on early diagnosis and the fact that prevention is better than cure," says Markham. "The success of breast and bowel cancer screening programmes in detecting disease supports that message. However, to benefit from early detection through screening, you must be able to see the disease on CT, which only sees cancer, and it must be amenable to treatment. The issue of screening is not as simple as you might think."
"You need medical supervision, and any screening you have should be targeted," she adds. "There is little value, if any, in whole body screening. We need to educate people to ask their doctors about specific screening procedures if they are suggested by the patient's family history."
Interest in WBCT now seems to be steadily waning. As it does, the broader lesson of the WBCT issue is that patients and healthcare providers must look beyond the surface when they assess new imaging technology applications, and make sure that they are fully aware of the dangers they pose.