New research has demonstated that breast cancer mortality rates in the UK have fallen steeply in the last two decades and more than in any other major European country.

The results, published by the BMJ, challenge frequently-made claims that survival after breast cancer is worse in the UK than elsewhere in western Europe. However, the apparently poor UK survival rates are misleading because of shortcomings in the way cancers are registered here, whereas the population-based mortality rates are reasonably reliable, argues an accompanying editorial.

Since the late 1980s, breast cancer mortality rates have been falling in many European countries due to the combined effects of early diagnosis, including screening, plus effective treatments. A team of researchers led by Philippe Autier from the International Prevention Research Institute in Lyon, France, examined changes in breast cancer mortality rates in women living in 30 European countries from 1980 to 2006.

Using World Health Organisation data, mortality rates were calculated for all women and by age group (ie less than 50, 50-69 and 70 years and over). From 1989 to 2006, breast cancer mortality decreased by 20% or more in 15 European countries and in the UK, mortality rates fell 30. In France, Finland and Sweden, countries that have also invested heavily in breast screening and new cancer drugs, mortality rates decreased by 10%-16%, the researchers say.

However, the findings also revealed that in central European countries, breast cancer mortality rates did not decline and even increased during the last two decades.

Women under 50 showed the biggest reductions in mortality rates, although screening at that age is uncommon, and this may reflect better targeting of effective treatments, the authors argued. They also suggest that the sustained decline observed in many countries seems to indicate that breast cancer mortality will continue to decrease beyond 2006.

In the aforementioned editorial, Valerie Beral and Richard Peto at the University of Oxford, point out that cancer registration in the UK is known to be incomplete and that defects in these data make cancer survival rates appear significantly worse than they really are. By contrast, the registration of death is complete and deaths from breast cancer are well recorded, except at old age.

They conclude that failure to make proper allowances for the shortcomings of cancer registration data “may well have led to misleading claims about the supposed inferiority of UK cancer treatment services in general”.