Verification of the cause of death in the trial of early detection of breast cancer. UK Trial of Early Detection of Breast Cancer Group. Trial Co-ordinating Centre.

The limitations of case review as a means of identifying errors in death certificates among breast cancer patients in a non-randomised trial of screening are illustrated by the findings of this large study. Records of 928 out of 990 deaths were available for review but were very variable in quality. Definite errors were found in 1%, errors were suspected in a further 5% and uncertainty about the cause of death, despite review, was recorded for 27%. The overall bias in reporting breast cancer deaths was less than 1%. It was concluded that the certified underlying cause of death without review provides an adequate endpoint for evaluating breast cancer screening programmes in the UK.