Doctors Fear Screening Tests Could Be Harmful

Unproven and unreliable screening tests could be harming patients instead of detecting early signs of disease. Doctors are warning patients not to use unregulated or ad hoc screening tests, including those bought on the internet, as they can give inconsistent results.

In some cases patients could be misdiagnosed with a disease, including cancer, causing unnecessary trauma and worrying.

Emerging techniques, such as whole body CT scans and exercise electrocardiograms, have been criticised by the British Medical Association’s Population Screening and Genetic Testing report.

And doctors have also cast doubt on the efficacy of prostate cancer screening tests and mammograms for women under the age of 50.

Dr Tony Calland, chairman of the BMA’s Welsh Council, said, ‘All doctors are wary of over-investigating the patient because many investigations carry some element of risk and there are very few perfect screening tests which give clear results in a simple form.

‘Therefore, any investigation should always be undertaken with the agreement of, or at the suggestion of a suitably medically qualified doctor.’

The report, by the BMA’s board of science, said whole body CT scanning can cause many false alarms leading to potentially dangerous invasive tests, and involves significant doses of radiation.

It added that there was no evidence that CT screening is useful for people without symptoms, but despite this some commercial companies are offering it and promoting it.

Two-thirds of men who have a high result after undergoing a Prostate Specific Antigen (PSA) test for prostate cancer, do not have the disease.

And some men with prostate cancer do not have high PSA levels.

The report said that there was no evidence to show whether treating localised prostate cancer does more good than harm.

Patients who undergo such tests in the mistaken belief they are benefiting their health could be put at risk, the report said.

The BMA claims that such tests are unlikely to be based on sound evidence and are not part of a proper screening system leading to appropriate follow-up and effective intervention.

There is also concern that people are not given balanced information and information and support for patients after a positive result is unlikely to be in place.

People who are given a false positive result may have to endure invasive and potentially dangerous follow-up investigations before they learn they do not have a disease or medical problem.

And those people who are wrongly told that they are well could delay the diagnosis and subsequent treatment of an undetected, potentially deadly disease.

Dr Vivienne Nathanson, the BMA’s head of science and ethics, said, ‘There is no doubt that some specific screening tests have the potential to save lives but this does not mean that there are no associated risks.

‘We must make sure that screening is of a high quality and that patients are given all the appropriate advice before they decide to participate.

‘People must be able to make an informed decision. After they receive positive results it is essential that people have appropriate support.

‘This is often lacking when screening is haphazard, and not part of a proper screening programme.’

She added, ‘We want the public to be extremely wary of unregulated screening.

‘People should be especially cautious about testing kits that can bought through the internet and mail order.’

Dr Chris Hiley, of the Prostate Cancer Charity, said, ‘The public must realise that there are both risks and benefits to screening but also that some apparently obvious benefits are not what they seem.

‘In the case of the PSA test – increasingly commonly used informally to indicate the possible presence of prostate cancer – doctors are still searching for the evidence that it saves men’s lives.’: What is screening?:Formal screening programmes are those with clear national policy and are based on sound evidence with explicit quality standards and quality assurance mechanisms in place. National screening programmes include: NHS breast screening programme – Breast Test Wales invites all women aged 50-67 for screening every three years but from next year the age limit will be extended to 70. Older women can self-refer themselves for screening. The programme has resulted in a 25% to 38% reduction in breast cancer mortality in women who underwent screening.

NHS cervical screening programme – in Wales all eligible women from 20 to 64 are invited for a test every three years.

Antenatal screening – blood tests are carried out to detect HIV, syphilis, Hepatitis B, sickle cell anaemia, other infections linked to pregnancy and to identify blood groups.

Newborn hearing screening programme aims to identify children born with a severe permanent hearing impairment at an early stage – early diagnosis is associated with improvements in language development and the general well-being of the child and family.