Abortion and Breast Cancer Oxford Group Adds New Wrinkle to Disinformation.

NRL News readers are likely as familiar with the many and varied forms of public denial of the abortion-breast cancer link (ABC link) as they are with the link itself. As night follows day, knee-jerk reactions follow whenever evidence for the ABC link is published, whether it appears in the medical or the popular press.

But disproving the old adage you can't teach an old denial new tricks, a group of Oxford University epidemiologists has just published an ABC study that is a novel new addition to the disinformation genre. The forum is this April's issue of the British Medical Association's Journal of Epidemiology and Community Health.

The new Oxford study, by M.J. Goldacre et al., appears to be a backlash by the professional British medical establishment against the credibility attained by the ABC link last year.

Last spring, the Royal College of Obstetricians and Gynaecologists (RCOG) publicly acknowledged, although it still considered all the evidence inconclusive, that the comprehensive review and meta-analysis of the ABC link that I wrote in collaboration with colleagues from the Penn State College of Medicine "could not be disregarded." (See May 2000 NRL News.) When the British popular press learned of the RCOG statement late in the summer, the issue surfaced briefly - - very briefly - - in the London tabloids. (See September 2000 NRL News.)

On the surface, the Oxford study appears to be the ideal type of study which includes two key components only rarely found together: a case-control record-linkage study.

Most epidemiological studies include a group of breast cancer patients ("cases") who are compared to a group of women of similar age and other important characteristics, but who do not have breast cancer ("controls"). But the "record linkage" part means that a study does not depend upon information provided by the study's participants gleaned from interviews or questionnaires. Rather, information has already been recorded as part of the subjects' medical records.

Consequently, there is not even the possibility of so-called "response bias." This hypothetical scenario imagines that women with breast cancer are more honest about a past abortion than are women who do not have breast cancer, thus skewing the results. The possibility of such bias has often been invoked by the nay-sayers to explain away the repeated finding of an ABC link in case-control studies which do not rely on record linkage.