Hi-tech screening services, which promise to detect early signs of heart disease, cancer and other conditions while they can still be cured, are being introduced in Britain despite warnings from doctors that they may do more harm than good.
A new allegation that breast screening, one of the longest established procedures, is being over-promoted to women who are not being alerted to the harm that can result is published today in the British Medical Journal.
Regular mammography to check for breast cancer is an established technology, backed by scientific expertise, which is popular with patients. But debate continues to rage over whether it saves lives or prompts unnecessary treatment. Hazel Thornton, a former breast cancer patient and visiting fellow at the University of Leicester, and Michael Baum, emeritus professor of surgery at University College, London, and a long-time critic of screening, have teamed up with a colleague to demand information for women that sets out the risks and benefits.
They cite evidence showing 1,200 women would have to be screened for 14 years to save one life from breast cancer while during that time scores would suffer anxiety, surgery and mastectomies for suspicious lumps that turned out to be benign.
The war over the risks and benefits of screening is likely to grow. Clinics offering whole body scans, diagnostic tests and checks for specific conditions such as skin cancer are springing up in London and in other cities promising to provide clients with the "ultimate health check".
At least four clinics have opened in the capital in the past three months offering tests lasting from 15 minutes to two hours and costing up to £1,000. Companies say the tests can reveal small tumours, aortic aneurysms (defects in the wall of the main blood vessel), bone erosion, artery deposits and osteoporosis (bone thinning).
Whole body screening is big business in America. Smart walk-in facilities such as the Ameriscan Body Imaging Centre are based in shopping malls and on high streets and are heavily advertised. They promise an ultra-fast image of vital internal organs for a price of about £650.
The selling point of the scans is summarised in one company's slogan: "You don't know what's inside until you look." Traditionally, doctors have performed health checks using the thermometer, the stethoscope and their skill as diagnosticians. Now the promise is that new technology will replace the application of a sensitive touch and a listening ear.
But British experts are sceptical. Richard Smith, editor of the British Medical Journal, said a whole body scan had become a fashionable gift in the US for people reaching milestone birthdays of 50, 60 or even 40. "You might be giving your loved one the supreme gift of extra years of life. Unfortunately, you may be more likely to give him or her a lorry load of anxiety and a series of invasive, painful and unnecessary investigations," he wrote.
The problem is that most scans throw up "abnormalities" but to distinguish those that are benign from those that indicate serious disease is often difficult. Dr Harvey Eisenberg, who runs a scanning service in Newport, California, said he referred 80 per cent of the clients he screened for further hospital checks.
"Emerging pathologies are almost always present. In 25,000 patients I have seen maybe 10 that were completely normal," he said.
Screening may wrongly indicate the presence of disease in some patients - the "false positive" findings - causing them to have painful and unnecessary investigations. An American patient who had a nodule detected on his lung in screening described how he had a lung biopsy to check for cancer, which revealed that the nodule was a healed scar that was non-threatening. The investigation led to him spending four days in hospital, enduring a painful procedure followed by several weeks' recuperation and left him with a bill of $47,000 (£30,000).
Stephen Swenson, professor of radiology at the Mayo Clinic, Rochester, Minnesota, said in the BMJ that screening for lung cancer at his clinic as part of a study had detected 56 cases of the disease over four years. "One could ask why screening should not be advocated. Several uncertainties, however, make it premature to advocate screening on a large scale," he said.
Although they found more early-stage lung cancers, what was unclear was whether this would delay progression of the disease, even with treatment, or whether the mortality associated with treating lesions which might turn out to be benign outweighed the gain from screening. Professor Swenson writes: "Some of the best doctors in the world have sincere differences of opinion about such screening .... If patients simply want to get scanned ... doctors should tell patients in explicit terms that such screening has no proved benefit and that serious risks could outweigh benefits (if there are any). Patients should understand that the stakes are high."
In their paper on breast screening in today's BMJ, Ms Thornton and Professor Baum say misconceptions on screening abound. Many people wrongly believe screening reduces the incidence of breast cancer, that all types of breast cancer progress and that early detection is always a benefit.
In fact, they say, screening contributes to a rise in the incidence of breast cancer and one in five cancers detected is ductal carcinoma in situ (DCIS), a type of breast cancer that may not progress. In 40 per cent of cases, DCIS results in a mastectomy, which may be unnecessary for the woman and expensive for the NHS.
They claim there has been "negligible improvement" in NHS screening leaflets because of the tension that exists with the screening service's need to boost uptake.
They conclude: "It is unacceptable that women taking tests continue to suffer damage and regret because they found out the harms of screening from experience. Unless women are able to make true informed choices, funding for the service will continue to be questioned."
A spokeswoman for the NHS Breast Screening Service said leaflets given to women were revised in 2001 to provide balanced information on benefits and limitations. "All women receive a copy of the leaflet with their invitation to screening which sets out what screening can and cannot do," she said.
Even the longest established form of screening in the UK - for cervical cancer - is not immune to criticism. In a separate survey in the BMJ, Angela Raffle, consultant in public health medicine in Avon, and colleagues, calculated that 1,000 women would have to be screened for 35 years to prevent one death. They point out that more than 80 per cent of abnormal findings at cervical screening do not progress to invasive cancer. "The same may well apply in other organs and the prophylactic [preventive] removal of colons, ovaries, breasts and gullets may be killing people without benefit," they say.
The rationale for screening - that we can nip diseases in the bud - is now being adopted by companies to make fat profits. But abnormalities are more common and difficult to interpret than people think. Early detection can improve survival - but it may also mean merely that patients spend more of their life with the knowledge that they have a fatal disease. Sometimes it is better not to know.
Examining a scraping of cells from the cervix under a microscope can reveal early changes, which may progress to cancer.
Mammography (an X-ray of the breast) can detect lumps in the breast that may be cancerous while they are too small to be felt.
Blood tests measure cholesterol levels and ECG can measure the heart rhythm. The ultimate test is angiography, in which X-rays of the coronary arteries are taken after being injected with a radio-opaque dye.
Testing faeces for the presence of occult (hidden) blood can detect signs of cancer. An internal examination using a flexible telescope can check for polyps, small growths from the intestinal wall, which may develop into cancer.
An ultrasound probe inserted in the vagina or pressed over the abdomen, combined with blood tests, may provide early warning of cancer. Trials are being run to establish its reliability.
Blood tests, with rectal examination, may indicate cancer.
A scan can detect nodules that may be early tumours.
A bone density scan can provide early warning of the bone-thinning disease osteoporosis, caused by loss of calcium.Reuse content