Fall in death rates fails to prove success of strategy

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The debate on breast screening for women between the ages of 50 and 64 every three years is distorted by three factors: the absence, to date, of a definitive evaluation of its benefits; conflicting international data for its impact on death rates; and the sudden fall in breast cancer death rates in England and Wales between 1985-1993 which cannot be attributed to screening.

Instead, the fall in death rates - 11 per cent for women aged 50-69 - is probably due to the growing use of the drug tamoxifen, whose benefits were confirmed only in 1990. This is at the root of objections to the massive investment by the NHS screening programme.

It will be 1997, at the very earliest, before statisticians can properly evaluate the NHS screening programme and show a decline or otherwise in deaths from breast cancer. Millions of pounds will have been committed to the programme while scientists scrabble around for funding for clinical trials of the long list of promising new drugs and hormones which may have greater benefits.

In addition, there are now doubts about how many lives screening will save. When, in 1987, the Government announced it was to set up the world's first breast screening programme the emerging clinical evidence for the benefits was impressive. A Swedish trial indicated screening could cut deaths by 30 per cent.

But earlier this year a Canadian review of six major clinical trials of screening concluded the figure was nearer 5 per cent. They concluded the "benefits were too small and the harm and cost too great" to justify a national programme.

Five years after screening took off nationally, Julietta Patnick, national co-ordinator of the NHS breast screening programme, said that "for most women the benefit [of screening] is reassurance [that they haven't got cancer]."

This does not allow for the huge burden of worry suffered by women who need further investigation but who subsequently are given the all clear.

Screening last year detected more than 6,000 cancers. However, only a proportion of these tumours will be curable; some will progress regardless of early detection and treatment, while others will be non-invasive, slow- growing, and unlikely to cause a problems in the woman's life-time.

On the other hand, the introduction of the screening programme has revolutionised the handling of breast disease in the UK. It reduced the lottery effect of NHS cancer care, and, in the long-run, it may be this overall improvement in care rather than screening itself which saves lives.