HEALTH New concerns over breast screening BBC News

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http://news.bbc.co.uk/1/hi/health/1607113.stm

 

Thursday, 18 October, 2001, 22:53 GMT 23:53 UK

New concerns over breast screening

 

 

Spotting cancers: But do mammograms save lives?

 

A fresh row has broken out over controversial claims that screening for breast

cancer may not actually be saving lives.

The research was first published last year, but has been re-examined following a

series of protests from cancer organisations over the findings.

 

Now one of the world's leading medical journals, The Lancet, agrees that there

is not enough evidence from large-scale trials to support breast screening.

 

However, cancer charities and the UK cancer screening programme disagree

strongly with their verdict.

 

 

 

At present, there is no reliable evidence from large randomised trials to

support screening mammography programmes

 

Richard Horton, Editor, The Lancet

All UK women aged between 50 and 64 are currently offered screening once every

three years.

 

It is hoped that tumours may be spotted earlier, making treatment more likely to

provide a cure.

 

Currently, it is reckoned that as many as 300 lives are saved a year by breast

screening - and more recent estimates suggest this annual figure is climbing

rapidly.

 

However, two Danish researchers from the Nordic Cochrane Centre in Copenhagen

have re-examined the seven large-scale studies looking into the effectiveness of

breast screening.

 

They say that the studies which support breast screening are either flawed or

weak, with the only two high quality studies showing no benefit at all.

 

In addition, they suggest that screening may result in women receiving more

aggressive treatments for cancer, increasing the number of mastectomies by

approximately 20%.

 

They write, in The Lancet: " We hope that women, clinicians and policy-makers

will consider these findings carefully when they decide whether or not to

attend, or support screening programmes. "

 

Flood of criticism

 

The Danish pair, Peter Gøtzsche and Ole Olsen, first voiced these criticisms

last year, and provoked a flood of protest as a result.

 

In the light of this, they say, they have thoroughly reviewed their work - and

reached the same conclusion.

 

" We found the results confirmed and strengthened our original conclusion, " they

wrote.

 

However, cancer organisations in the UK have repeated their attacks on the

conclusions.

 

Many are worried that any adverse publicity about breast screening will dissuade

women from coming forward.

 

Stephen Duffy, an expert in breast screening from the Imperial Cancer Research

Fund, said that the five studies which supported the use of mammograms should

not have been excluded.

 

He said: " Studies in the UK and Sweden by ICRF and others have shown breast

cancer screening substantially reduces women's risk of dying of breast cancer.

 

" Research published only in May demonstrated that women who attend regular

breast screenings may reduce their risk of dying by more than 50%. "

 

Disagreements

 

A spokesman for the UK Breast Screening Programme agreed: " The way Gøtzsche and

Olsen classified studies was based on criteria that would not be agreed by many

experts in the field.

 

" Indeed many researchers would classify all seven studies as of similar quality,

and when the results from all seven studies are combined, there is clear

evidence of the benefit from mammography. "

 

If existing studies are too weak to support the use of breast screening, then

the chances of organising large-scale replacements are slim, as these would have

to involve a sizeable " control " sample who would not be screened for the

purposes of comparison.

 

As most clinicians already feel that breast screening offers a significant

benefit, it would probably be felt ethically unsound to leave so many women

without it.

 

However, the fact that The Lancet now backs the Danish team is a significant

move in supporting those who question the benefits of breast screening.

 

Editor Richard Horton wrote: " Women should expect doctors to secure the best

evidence about the value of screening mammography.

 

" At present, there is no reliable evidence from large randomised trials to

support screening mammography programmes. "

 

Professor Michael Baum, from the Portland Hospital in London, says that it is

now right that women should be presented with all the evidence about screening

before they give their consent.

 

He said: " Even with the most optimistic estimates on saving lives, you would

still have to screen 1,000 women for 10 years to save one life.

 

" If you have one significant adverse event which costs a life in this group over

this period, all that benefit is cancelled out.

 

" The Lancet is a highly influential journal and if they are backing this review,

it's highly significant. "