BREAST CANCER SCREENING COULD BE HARMING FAR MORE WOMEN THAN

[Daanyeer]

Breast cancer test questioned as study finds only one life saved per 258 women screened


By Rachel Quigley
4th August 2010

Breast cancer screening could be harming far more women than it helps, according to a review.

The programme, which offers tests to almost two million women a year, is being called into question by leading epidemiologist Professor Klim McPherson.
The Oxford University specialist said the benefits are finely balanced against its harms of over diagnosis, which is followed by unnecessary treatment and suffering.
Reviewing the evidence for and against screening, Professor McPherson concluded that 258 women in the UK would have to be screened to avoid one death.
Breast screening has divided the medical establishment for more than 20 years and the new review has now raised questions about all screening programmes including those for bowel, prostate and cervical cancer.

The review claims that the benefits of screen cancer - early detection and rapid treatment - have never been properly weighed against the drawbacks - the central one being that in some cases the cancer detected does not need treating as sometimes it can heal itself or is very slow growing.

In these cases the individual spends their life in the shadow of cancer without living longer. They may be treated, suffering pain and anxiety, but to no avail.

The breast screening programme offers a mammogram to all women aged between 50 and 70 but this is to be extended from 47 to 73 in 2012.

Advocates of the programme say it saves 1,400 deaths a year and claim it saves two women's lives for every one who receives unnecessary treatment.

But the critics dispute these figures, claiming that for every woman saved, as many as 10 undergo unnecessary treatment, which can even go as far as a mastectomy in extreme cases.



Professor McPherson, was asked to review the evidence by the British Medical Journal after a dispute last March.

The BMJ published a paper on breast screening in Denmark which showed that deaths from breast cancer had fallen faster in areas without screening than in those where it was used.

It said this decline was 'more likely explained by changes in risk factors and improved treatment rather than by screening mammography'.

The paper provoked a flurry of responses accusing the researchers of 'undermining the trust of women' and the BMJ of 'taking sides'.

Professor McPherson concluded that breast screening reduces the death rate by 14 per cent in the under 60s and by 32 per cent in the under 70s.

But even this is of small benefit, he said, because at age 60 the risk of death from breast cancer over the next 15 years is just 1.2 per cent - 258 woman in the UK would have to be screened to avoid one death.
He said: 'Individual benefit from mammography is thus very small, but this is not widely understood.

'In part this is due to obfuscation from organisers of mammography services assuming that a positive emphasis is needed to ensure reasonable compliance.'

He has called for a 'full examination of all the data' and more honesty from the NHS about the scientific uncertainties. He also suggests that the National Institute for Clinical Excellence (NICE) should review the evidence.

'There is no doubt that screening for breast cancer has limited benefit and some possibility of harm for an individual woman and is of marginal cost-effectiveness for the community,' he said.

'The NHS screening programme needs to be really clear about the uncertainties when communicating with women.

'More importantly we all need to understand better how a national programme of such importance could exist for so long with so many unanswered questions.'

Editor of the BMJ Fi Godlee, who asked Professor McPherson to review the evidence, said: 'I don't think the public understands that screening carries both risks and benefits.

'Often doctors don't either – they are caught up by the notion that prevention is better than cure.

'If you are intervening with a healthy population in the hope you can make their lives better and longer then the burden of proof is much higher and the strength of the evidence you need greater.'

'The screening lobby thinks the BMJ has got a bee in its bonnet about screening. That is not the case – we follow the evidence.

'The Danish team do good work which is very thorough and of good quality. It is fair to say that we have not had the same quality of submissions from the other side.

'We would be delighted if someone came forward with a robust defence of the screening programme – I don't think they have done that.'

Sarah Sellars, director of the NHS Breast Screening Programme, said: 'The vast majority of evidence from properly conducted research clearly shows that regular mammography reduces deaths from breast cancer.

'The World Health Organisation's International Agency for Research on Cancer (IARC) concluded that there is a 35 per cent reduction in mortality from breast cancer among regularly screened women aged 50-69 years old.

'There is a risk of overdiagnosis, and possible subsequent overtreatment, associated with any screening programme.

'But recent independent studies show the risk of overdiagnosis is very much lower than some other estimates have claimed, and that the benefits far outweigh the risks.'


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