New report demonstrates changes in breast cancer mortality hard to quantify and evaluate

August 13, 2010

A retrospective analysis of breast cancer mortality rates in 30 European countries demonstrated a wide variation in rates and trends, reflecting the difficulty in obtaining accurate, meaningful statistics.  The average trend across the 30 countries showed a 19% decline in mortality from 1989 to 2006, but this included a wide range of individual trends by country, including a 17% increase in mortality in Romania, and a 45% decrease in mortality in Iceland.  The analysis was based on cause of death reports in each country, which may be of limited reliability, according to the authors.  It is difficult to tease out from the limited data, the relative impact of various interventions, such as mammography screening, endocrine treatment, and chemotherapy regimens.

However, epidemiologists Valerie Beral and Richard Peto point out in an accompanying editorial, that this report gives a more accurate picture of breast cancer in the UK than previous reports showing lower breast cancer survival.  The current report showed a more rapid decline in breast cancer mortality in the UK than shown in most other European countries.  They point out that population based mortality trends are reasonably reliable because a death certificate is legally required before someone can be buried or cremated, while cancer registration is not required by law in the UK and is known to be somewhat incomplete.  "Partly because of this incompleteness, survival calculations based on registry data make UK cancer survival rates seem significantly worse than they really are," they say.

Interestingly, there was a more modest decline in mortality in France than the study authors expected (a 1.4% decline per year), despite "having one of the highest number of mammography units per million women, having the highest spending on cancer drugs per person in Europe, being at the forefront in use of new costly treatments, and devoting much effort to enhancing adherence to guidelines."