Health: Breast screening cuts cancer deaths by half

A 10-year study of breast screening in women under 50 has found it almost halved the death rate from breast cancer. However, British experts tell Jeremy Laurance, Health Editor, that although breast screening is effective in younger women it should not be provided on the NHS.

Regular breast screening for early signs of cancer in women aged 39- 49 does save lives, researchers have concluded. A study of 11,000 women who were screened every 18 months and 14,000 women who were not found a marked difference in deaths from breast cancer after 10 years.

About one in 28 women in both groups developed cancer but in the screened group 18 died compared with 40 deaths in the unscreened group. The difference, of 45 per cent, is probably attributable to earlier treatment of the screened group.

The study, conducted in Sweden and published in Cancer, will add to the controversy over breast screening in younger women which has been dismissed as ineffective. Experts have argued that the greater density of younger women's breasts makes it harder to detect the tiny calcified lumps that can signal the onset of cancer.

An editorial in the journal says this wrongly implies that there is a sudden change in women's breasts at age 50. "Many younger women have fatty breasts and many older women have denser breasts," it says. Improvements in mammographic techniques have made detection of cancer in women with denser breasts possible but no long-term trials in younger women have been carried out.

Based on the study's findings, the editorial, by Dr Stephen Feig of the Jefferson Medical College, Philadelphia, US, says the death rate might have been reduced by 75 per cent if screening of women aged 40-49 was carried out annually rather than every 18 months.

Dr Robin Wilson, clinical director of the breast service at Nottingham City Hospital, said the findings were "pretty impressive" but said the trial was too small to provide a definitive answer and there were questions about the cost and the risks to women of unnecessary investigations.

The NHS breast screening programme for women aged 50 to 64 is estimated to reduce deaths by 1 per cent at a cost of pounds 35m a year. In women under 50, in whom breast cancer is less common, it has been estimated it would reduce deaths by 0.1 per cent making it 10 times more expensive. The Royal College of Radiologists says women under 50 could benefit from screening but it should not be a freely funded service.

Dr Wilson said: "I don't think there is any doubt that screening done properly does reduce mortality in that age group [39-49]. But is it something the NHS should pay for? The argument is you could save more lives by spending the money in other ways."

A trial of screening involving 195,000 women aged 40 to 41 in 30 centres around the country began in 1991 but it will be 15 years before the results are known because of the need for long-term follow-up of those who develop cancer. Dr Wilson said it was imperative women under 50 offered screening were made aware of the risks. One in 10 women would be recalled for further tests subjecting them to anxiety and the possibility of a biopsy. Some would be falsely reassured because screening cannot detect all cancers. They must be warned to seek medical help should they notice a lump.