In Part I of this three-part series of articles on the link between abortion and breast cancer (the ABC link), I described the two primary ways in which abortion increases a woman’s future risk of breast cancer:
1. via loss of the protective effect of an otherwise full-term pregnancy, and
2. via the increase in cancer-vulnerable tissue produced by the pregnancy hormones, making women who choose abortion more likely to get breast cancer than if they had not gotten pregnant in the first place.
There is no debate about the former. Scientists have long understood that the risk of breast cancer is reduced when a woman completes a full-term pregnancy. This “protective effect of childbearing” is lost with an abortion.
The latter trend, known among epidemiologists as the “independent risk” of abortion, has been the center of the controversy raging in the public square. Hence, it has been the main area in which scientific evidence has been systematically covered up for some 40 years now. This cover-up is the subject of our inquiry in the present essay.
Evidence of this independent risk of abortion first showed up among American women in a prominent study from Malcolm Pike and colleagues at USC, published in 1981 in the British Journal of Cancer. They found an elevated risk of 140%, a result Pike himself would attempt to minimize years later.
The first study clearly aimed at covering up this result appeared in the same journal the following year. The 1982 study was conducted by the group led by Sir Richard Doll. Doll’s then impeccable reputation as Oxford’s top epidemiologist was enough to repress the red flags raised by Pike’s prominent study.
In their study, the Doll group claimed—right in the study’s abstract—that their “results are entirely reassuring, being, in fact, more compatible with protective effects (of abortion vis-à-vis breast cancer) than the reverse.” They also claimed a much larger and older study population than Pike’s—1,176 women aged 16-50, compared to only 163 women under age 33—implying a much more statistically reliable study.
Like all epidemiological studies, statistical tables full of numbers dominated the pages. But note, the actual number of women who had had an induced abortion was nowhere to be found; the lone descriptor was “only a handful.”
Hence, far from being “entirely reassuring” about the safety of abortion, the Doll study was in reality, entirely irrelevant. Almost all their data were derived from spontaneous abortion (miscarriage), a natural phenomenon which does not elevate breast cancer risk.
To this day, the conflation of spontaneous and induced abortion is used by health authorities worldwide to dilute the connection with induced abortion to render it insignificant. It is one of the major ways by which the ABC link is dismissed.
Not surprisingly, the successors of the very same group at Oxford constitute one of those prominent authorities. They have published at least five ABC-link cover-up studies. The most prominent principally authored by Valerie Beral, appeared in the prestigious journal The Lancet in 2004. (I wrote about this study at length in the May 2004 edition of National Right to Life News.)
Some background is needed to understand the central role of the 2004 Beral “reanalysis.” In 1996 my colleagues at Penn State Medical College and I published a “comprehensive review and meta-analysis” of the independent ABC. At that time, there were 23 extant published studies from around the world. Putting them all together revealed a statistically significant, 30% overall increased risk of breast cancer among women who had had any abortions.
By 2004, the number of published studies with ABC link data had risen to 41, but Beral’s Lancet “reanalysis” assembled data from 53 studies, many of them not previously published. One would think, logically, that Beral’s study comprised the 41 extant published studies and another 12 as yet unpublished ones.
In fact that would be way off the mark. Beral’s “reanalysis” was actually of 52 studies. Only 24 of them had been previously published while 28 studies (more than half) not previously published. Knowledge of the criteria for exclusion (of the previously published) and inclusion (of the previously unpublished) is crucial.
On what basis were 17 published studies excluded from the Beral “reanalysis”? Eleven were excluded for the following four dubious reasons:
“Principal investigators…could not be traced”
“original data could not be retrieved by the principal investigators”
“researchers declined to take part in the collaboration”
“principal investigators judged their own information on induced abortion to be unreliable” (even though it had been vetted by peer review and published in a prominent medical journal—and never retracted).
In addition another four previously published studies were simply never mentioned at all. Only two were excluded for legitimate scientific reasons.
The fact that the majority of the previously unpublished studies had not stood the test of peer review is troubling enough. But a closer look at the results of studies Beral et al. excluded is even more revealing.
Of the 41 previously published studies, 29 show increased risk of breast cancer among women who have chosen abortion. (Epidemiologists call this a “positive association.”)
Sixteen were “statistically significant,” which means there is at least a 95% certainty that the results cannot be explained by chance. But Beral excludes 10 of these for reasons that simply are not supportable.
If we average all of the 15 studies that Beral inappropriately excluded, they show an average breast cancer risk increase of 80% among women who had chosen abortion. By selectively eliminating studies that show an ABC link, Beral is able to find there is no significant effect of abortion on the risk of breast cancer.
Having thrown out studies that contradict her thesis, she then included studies that are plagued with serious deficiencies.
Beral divided them into two types: (1) those which used retrospective methods of data collection (i.e., interviews of breast cancer patients versus women who had not had breast cancer), and (2) those which used prospective methods (i.e., medical records taken long before breast cancer diagnosis).
Beral told the Washington Post at the time that retrospective data-based studies are thought to be less reliable. Women with breast cancer, she said, “are more likely than healthy women to reveal they had an abortion, leading to the conclusion that there are more abortions among this group.” This “reporting bias” or “response bias” is a key to Beral’s argument.
But something you’d never know is that this hypothesis has been disproved over and over again in studies as far flung as Japan, the United States, and Greece!
There is only one study that claims direct evidence for such a reporting/response bias— a Swedish study, conducted by a group headed by Olav Meirik of the World Health Organization (WHO). They did so based on an assumption that breast cancer patients had “overreported” abortions (i.e., imagined abortions that had never taken place!). However, in 1998 the authors publicly retracted that assumption!
Notwithstanding this retraction Beral and others who deny the ABC link continue to cling to the original 1991 study as evidence of reporting bias! Meanwhile, other studies in the U.S. clearly showed no such bias in ABC link research.
In Part Three I will review the unseemly parade of about one fraudulent ABC link paper per year between 1997 and 2008. They issued from such prestigious institutions as Oxford (again and again!), Harvard and the Karolinska Institute in Sweden, where the Nobel Prizes come from.
All were based on prospective data, so they could be touted as superior in design and execution. But you won’t believe some of the garbage that passed as science, in a clear effort to convince the world that the ABC link is a fiction.
Chelsea Garcia is a political writer with a special interest in international relations and social issues. Events surrounding the war in Ukraine and the war in Israel are a major focus for political journalists. But as a former local reporter, she is also interested in national politics.
Chelsea Garcia studied media, communication and political science in Texas, USA, and learned the journalistic trade during an internship at a daily newspaper. In addition to her political writing, she is pursuing a master's degree in multimedia and writing at Texas.
