In 1988, the NHS began routine three yearly tests on women aged 50 to 64. But the expert committee which recommended routine testing said it was unclear at what age women were likely to benefit most from screening.

Researchers say the current breast screening programme in North West England reduces deaths from cancer by 12.8%, preventing 4,079 deaths over a period of 27 years.

Cancer experts estimate around one in 12 women in the UK will develop cancer at some point in their lives.

Using a computer simulation programme and 1987 data on women in the region, the researchers have shown that extending testing to women aged between 65 and 69 could cut deaths from cancer by 16.4% - at a cost of �2,990 per year of life saved.

Is it better to save more old people or save fewer younger people for longer?

The research, published in this week's British Medical Journal, also shows that reducing the gap between testing from three to two years reduces deaths by 15.3%, costing �3,545 per year of life saved.

The total cost of the current screening programme is �30.9m. Increasing the number of tests would cost �40.6m and extending the age range for tests would cost �39.6m.

Most of the money would be eaten up by follow-up tests on women with suspicious symptoms, but some cash would be saved by catching cancers earlier.

Cost effective

The researchers say that extending the age range prevents more deaths, but reducing the gap between screenings allows people to live longer.

They believe the difference between the two options is "so small that either could be chosen".

And they say it is up to the NHS to choose whether it believes either course of action would be cost effective.

"It depends on the value the NHS is willing to place on improvements in the effectiveness of programmes," say the researchers, who are led by Dr Rob Boer of Erasmus University, Rotterdam.

Self-referral

In the same edition of the British Medical Journal, an East Sussex pilot study shows that the majority of women over 65 do not go for tests, even though screening saves lives and the women are entitled to refer themselves.

The study says many appear to be unaware they can refer themselves or assume they would be invited to attend if they were at risk.

In the pilot study, women over 65 are being invited to attend mobile screening units along with younger women.

Only 7% of women over 65 had self-referred previously and the majority of women aged 68 and 69 had not been screened for over five years - even though they were more likely to develop breast cancer than younger women.

Competition

The final results of the pilot will not be ready until the year 2000, but the researchers, led by Dr Linda Garvican of the South East Institute for Public Health, say preliminary results show "the potential for a high uptake rate and a high cancer detection rate in older women routinely invited for breast screening".