Breast cancer screening 'may not cut deaths'

Breast cancer screening programmes may have no effect on death rates, researchers said today.

Danish experts cast doubt on the benefits of mammography after research showed few differences between women who were screened and those who were not screened when it comes to deaths from breast cancer.

It follows research last July by the same team which concluded that one in three breast cancers detected by screening may actually be harmless.

That study, based on data from the UK, Canada, Australia, Sweden and Norway, suggested some women undergo unnecessary treatment for cancers that are unlikely to kill them or spread.

Some cancers grow so slowly that the patient dies of other causes first, or the cancer remains dormant or regresses.

The researchers, from the Nordic Cochrane Centre in Denmark, said cancer screening programmes could lead to “overdiagnosis”.

In their latest 10-year study, published online in the British Medical Journal (BMJ), experts from the Centre found death rates from breast cancer fell 1% per year in screened areas among Danish women aged 55 to 74 and by 2% in non-screened areas.

In women too young to benefit from screening (aged 35 to 54), breast cancer death rates fell by 5% per year in the screened areas and by 6% per year in the non-screened areas.

For older age groups (75 to 84), there was little change over time both in screened and non-screened areas.

The authors wrote: “The reductions in breast cancer mortality we observed in screening regions were similar or less than those in non-screened areas and in younger age groups, and are more likely explained by changes in risk factors and improved treatment than by screening mammography.”

The researchers said their findings were similar to results from other countries, including the UK.