While doctors consider stepping up breast cancer screening, new data has revealed a regularly screened woman who develops cancer is no better off than a victim who had never had a mammogram.

And a new major study has confirmed that breast screening is of very little benefit to women aged between 40 and 49.

The British Medical Journal reports that the findings of large controlled studies show that women diagnosed with cancer between screenings have the same prognosis the likely progress of the disease as those who were never screened (BMJ, January 14, 1995).

These cancers that develop between screenings, called interval cancers, were thought to be far more virulent, but a report in the American Journal of Surgery (1994;169: 538-42) described 24 women with interval cancer whose 10-year survival rate was 85 per cent.

And mammography is of little benefit for women screened between the ages of 40 and 49, a new American study has confirmed.

In an analysis of 13 major studies carried out between 1966 and 1993, researchers from the University of California found that screening had no affect on cancer deaths of women in that age group after a seven to nine year follow-up.

But women aged between 50 and 74 did benefit from screening, irrespective of how many times they were given mammograms. The evidence argues against more frequent screening, they concluded, as it would merely increase costs but not detection (JAMA, January 11, 1995). A study carried out at the Withington Hospital in Manchester, England concluded, however, that anything more than a three-year interval between screenings was too long for women aged between 50 and 64 (BMJ, January 28, 1995).

Prostate cancer screening tests should not become standard practice, a leading expert from the Netherlands has concluded. Fritz Schroder from Erasmus University in Rotterdam said the balance of risk to benefit has not been established. Most prostate cancers are undetected, cause no symptoms and do not contribute to death. The US Food and Drug Administration approved a blood test last year for detecting the cancer.

!ABMJ, January 21, 1995.