In A Day at the Races, the Marx Brothers’ 1937 classic, a generously
unholstered matron, played by Margaret Dumont, threatens to leave the
Standish Sanatorium because it cannot find anything wrong with her. “I’m
going to someone who understands me, I’m going to Dr Hackenbush! . . . Why,
I didn’t know there was a thing the matter with me until I met him!” she
says. Hackenbush, played by Groucho, takes her money and feeds her pills
intended for horses.
Some doctors suspect that today’s craze for screening is not so very
different. Feeling healthy? Come and have a CT scan and we’ll soon find
you’re not. It’s hard to escape the relentless plugging of health scans from
pop-up ads on the internet to women’s magazines and even Men’s Health. We
haven’t gone as far as the US, where CT scans are advertised on gantries
over freeways, but the message is the same: a day spent being screened could
save your life.
Rejecting this seductive patter may seem contrary, even Luddite. But screening
can be dangerous. Companies offering scans imply that being screened will
detect hidden medical problems so early that they can be nipped in the bud.
The process is compared to giving the car a service or an MOT. Anybody
failing to listen is selling themselves and their loved ones short. The
presumption is that by acting now we can buy our way out of future
ill-health and that it’s worth spending a lot of money to do it. When an
American physician asked a group of 55-year-olds if they regarded cancer
screening as an obligation, most said they did. Asked to choose between a
whole-body scan and $1,000 in cash, 73 per cent went for the scan.
Exact UK figures are scarce, partly because the scanning companies are
relatively new. But Prescan, who opened in London just eight months ago, say
they have carried out an average of 25 full body scans a week at an average
cost of £1,200 — a total of £960,000.
But screening has a downside. At worst, it may increase your risk of disease.
Equally, it could set you off on a conveyer-belt of ever more intrusive and
unpleasant tests that will leave you poorer but no healthier.
This month, the Committee on the Medical Aspects of Radiation in the
Environment will discuss a draft report on the radiation doses from
unregulated screening. The Department of Health asked it to investigate
after warnings from bodies including the British Medical Association that
scans could do more harm than good.
CT scans represent only about 6 per cent of the X-rays done in Britain, but
are responsible for 40 per cent of the radiation exposure. A typical dose
from a CT scanner is around 10 millisieverts per scan, 500 times as much as
in a typical chest X-ray.
That may be a price worth paying if the scan is being used to monitor
treatment of a serious disease, but to expose healthy people to such high
doses is hard to justify. The estimate is that a dose this high increases
the lifetime risk of cancer by about one in 2,000. Are the benefits of CT
scanning of healthy people greater than this? The scanning clinics’ response
is that in 2 to 3 per cent of those scanned, some life-threatening
abnormality is found. Sometimes they can be treated successfully. For these
individuals, the benefit certainly exceeds the risks.
But for the generality, we simply don’t know. For every dangerous aneurysm
discovered and dealt with, there are a plethora of what radiologists call
“incidentalomas” — odd abnormalities that probably don’t matter but often
need further investigations to make sure. In one US study of 1,200 body
scans, nearly a third of patients were advised to have further tests, most
of them unnecessary because there wasn’t anything wrong.
CT scans produce amazingly detailed images, and no two individuals are
identical. As one American radiologist put it: “With this level of
information, I have yet to see a normal patient.” Scanning clinics, well
aware of these criticisms, have focused on magnetic resonance imaging (MRI)
rather than CT scans. Prescan, for example, based in London, says: “CT scans
have a very high incidence of false positives. In other words, when the scan
does find something (which can be as high as 90 per cent of the time) it has
to be investigated with further costly and often invasive procedures.
“The finding is usually a benign tumour, cyst or scar tissue but the person
has incurred the cost and the discomfort of further tests — plus the stress
of waiting for results.” Peter Mace, the assistant medical director of BUPA,
said that the private health insurance company does not offer whole-body
scanning using either CT or MRI because the benefits have not been clearly
demonstrated and the radiation dose — in the case of CT — is significant.
“What we do do are closely focused scans on the heart, looking for evidence of
calcium,” he said.
The rationale for this is that as hardening of the arteries develops, the
amount of calcium detectable by CT scanning rises, and there are studies
that correlate calcium scores with the risk of heart attacks. The issue is
whether knowing this calcium score adds to the predictive value of the other
risk factors for heart disease, such as cholesterol levels, blood pressure
and smoking status. Last year the American Heart Association concluded that
it did, but only in people at medium risk. In those of low or high risk, it
adds no extra predictive value.
“I think that there is a reasonable amount of evidence, and it is growing,
that coronary calcium is important,” Dr Mace says. “What we haven’t got is
evidence that knowing the coronary calcium score will make people live
longer. But inferentially, using common sense, I believe that is true.”
Most people tend to see screening as an entirely benign procedure. But it is
not. Muir Gray, for many years programme director of the UK National
Screening Committee, puts it strongly. “All screening progammes do harm,” he
said. “Some do good as well, and some do more harm than good.” For NHS
screening programmes, strict rules apply. The disease being screened for
must have an early stage, for which an effective treatment exists. There
must be an effective test, shown to work in properly conducted trials, that
does not throw up too many false results, either positive or negative. And
the benefits in lives saved must exceed the risks.
Even when these criteria are met it is hard to be sure that a screening
programme is justified, as the arguments over the effectiveness of breast
mammography make clear. The claim is that breast cancer screening saves 300
lives a year in Britain, but critics contest it. Their reasons include a
dearth of convincing blind trials, and that scans may pick up early tumours
that never develop, causing unnecessary treatment.
Cervical screening is less contentious, and the NHS is now slowly implementing
a bowel cancer screening programme. There is good evidence that the use of
ultrasound to screen for aortic aneurysms — swellings of the blood vessels
in the abdomen that can burst without warning — would be costeffective.
Private screening clinics do not need to satisfy such demanding criteria. They
rely on the worried well — or, as one wag put it, the worried wealthy — to
pay large sums of money for tests that have not been shown to be
cost-effective or really to save lives.
There is anecdotal evidence of patients for whom such a test does pick up
something that matters — an aneurysm or a tumour. If it can be treated
successfully, that is a positive outcome. If not, it may mean that someone
has longer to live in the knowledge of an incurable disease.
The medical literature is short of any convincing evidence that MRI scans,
used on healthy people, save lives — one reason why BUPA does not offer
them, Dr Mace says. But companies such as Prescan, Preventicum and
ScanandScreen do. A whole-body MRI scan at Prescan costs £1,090, or £1,390
if you add a CT scan of the heart.
Prescan failed to respond to my requests for evidence that such scans do more
than lighten a patient’s wallet. What we do know is that such scans do
typically pick up medically significant findings in 1 to 2 per cent of
healthy people tested.
In a proportion of these positive findings, something can be done. For
example, the discovery of an aneurysm in the brain might justify life-saving
surgery to repair it.
But even then the situation is more complicated than it seems, as a team from
the University of Edinburgh makes clear in the latest issue of the Journal
of Medical Screening. For healthy people with no family history, the
lifetime risk of a bleed from an aneurysm in the brain is 0.6 per cent. But
aneurysms are found in about 2 per cent of people scanned.
That means that for every three found, less than one would ever have been a
problem. But once an aneurysm is found, treatment is likely. If 1,000 adults
were screened, 20 of them would be found with an aneurysm, only six of which
would ever have bled. If all of these 20 were treated surgically, two would
be dead, disabled or brain-damaged by one year after the operation, and in
eight cases out of the 20 the operation would have been only partly
successful, leaving a risk of a future bleed.
That makes the discovery of an aneurysm a far less positive thing than the
scanning companies pretend. It would, in fact, face the patient with an
agonising choice and a fair chance of being killed or disabled to treat a
condition that might never have caused him or her any harm.
The Edinburgh team, led by Dr Rustam Al-Shahi Salman, are in little doubt. The
balance of risks and benefits mean that brain MRI scans “cannot be
recommended outside the context of a research study”. They go on:
“Undoubtedly, further research is needed to establish whether whole-body
screening is effective, although it would require a very large randomised
trial.
“Regulatory bodies in the UK should follow the example of others such as
Health Canada and the Royal Australian and New Zealand College of
Radiologists by stating their view on whether whole-body screening is
appropriate.” MRI scans do have appropriate uses in screening. They are, for
example, better at detecting breast cancer in young women than conventional
mammography, and the National Institute for Health and Clinical Excellence
recommends their use in women between 20 and 49 known to be at high risk of
the disease because they carry a predisposing gene.
At the very least, the companies that offer whole-body scans should make it
clear that the procedure is unproven and that there is no robust evidence to
show health benefits from undergoing it.
“Why not treat a loved one or a valued employee to the ultimate spring gift?”
asks Preventicum on its website. Frankly, it’s a gift I would have no
hesitation in turning down. I’d just as soon have a horse pill.
The average cost
Total body MRI scan: £1,090 Includes MRI scan of brain and skull,
arteries to the brain, abdomen and pelvis (prostate for men and uterus and
ovaries for women)
Total body MRI scan and cardio: £1,390 As above, plus spirometry
(measures function of the lungs) and exercise ECG (measures function of the
heart and risk of heart attack)
Total body MRI scan and CT scan: £1,390 As above, plus CT heart
scan (calcium scoring of coronary arteries, above the age of 45), and CT
lung scan (if over 40 and a heavy smoker)
Complete check-up: £3,400 Consultation with a doctor. More than
40 blood tests and urine analysis. Hearing, ECG, tonometry and spirometry.
Ultrasound examinations of carotid arteries, abdominal aorta, spleen,
kidneys, adrenals, liver, pancreas, gallbladder, bladder, common bile duct,
prostate, ovaries and uterus. Colonoscopy. Total body MRI
Individual scans of separate parts of the body (as detailed on cover):
£5,000
