This is not terribly surprising, considering that the NCI’s denial of any ABC link has always been misleading, to say the least, since, as they have always acknowledged, a full-term pregnancy lowers a woman’s long term risk of breast cancer. Hence, any pregnant woman who chooses abortion will have a higher long term risk of breast cancer than if she chooses not to have an abortion. Warning a woman considering abortion is therefore a medical duty of any abortion practitioner, according to any standard of medical ethics, even if one disagrees—as Colby Cosh does—with the finding that abortion increases breast cancer risk beyond that which would have obtained if the woman did not get pregnant in the first place. As Cosh puts it in his hit piece: “Abortion probably does increase breast cancer risk insofar as it eliminates one pregnancy…(but)…Whether abortion imposes a distinct burden of cancer risk is another question.” Yes, but it is a question just for academics, and of no use to a woman who is already pregnant.
In fact, although this “Summary Report” of the “workshop” had not been revised since May of 2003, it was revised to reiterate the no ABC link conclusion just this January 12, four days after the Globe & Mail’s Galloway called the NCI to find out why the main organizer of the workshop had published the contrary conclusion, i.e., that a significant, 40% risk increase with induced abortion was “consistent with the effects observed in previous studies on younger women.” Not only did Galloway’s request go “unanswered”, but outrageously, the revised statement contains the claim that “the evidence overall still does not support early termination of pregnancy as a cause of breast cancer.” But it contains nothing about recent published evidence—especially that co-authored by Dr. Brinton—to the contrary.
But perhaps more important than the findings themselves is the authorship of the Seattle study. The study was done by Dr. Janet Daling’s group at the Fred Hutchinson Cancer Research Center in Seattle, in collaboration with the NCI’s Chief of the Hormonal and Reproductive Epidemiology Branch of the Division of Cancer Epidemiology and Genetics, Dr. Louise Brinton. This is particularly relevant because Dr. Brinton was the chief organizer of the NCI’s 2003 “workshop” on “Early Reproductive Events and Breast Cancer”, a conference which reported as “well established”, that “Induced abortion is not associated with an increase in breast cancer risk.” In other words, this conference officially concluded that there is no ABC link, and it is this conclusion that is referred to as still definitive on the NCI “fact sheet” on abortion and breast cancer risk.
It is not my aim here to enumerate the flaws in Cosh’s analysis. Rather, my main aim is to set the record straight on the real significance of the new Seattle study with respect to the ABC link. Yes, it is important that a new study has reproduced a finding of significantly increased breast cancer risk among women who’ve had any abortions; a finding now demonstrated in the vast majority of the dozens of studies from around the world, going back to 1957. Just last year, two more studies—one in Turkey and one in China—have also verified the link. As the authors of the Seattle study say about their own results, they were “consistent with the effects observed in previous studies on younger women.” (This study was based on women under age 45, but the same magnitude of the abortion effect has been observed in many studies that included older women as well.)
Among “known and suspected breast cancer risk factors (which) were examined separately as potential confounders for the main effects of all the other risk factors” are included “annual income” and “body mass index” (i.e., obesity). But importantly, only those potential confounding variables which produced at least a 10% change in the odds ratio (i.e., the risk increase) for any of the risk factors “were considered as adjustment factors in the final model.” Hence, Cosh’s claim that obesity and income differences were not accounted for in the results is a material misrepresentation of the Seattle paper, and he should publish a retraction.
Not one to rely on secondary sources, however, Cosh wades into the primary source: the Seattle study itself in the prestigious cancer epidemiology journal “Cancer Epidemiology, Biomarkers and Prevention.” Unfortunately, he wades in only ankle-deep and picks apart the key data table, apparently without reading all that pesky small print that details the study’s methodology. In minimizing the statistically significant 40% increased risk that shows up in the table among women who’ve had any abortions, Cosh claims that most of the risk increase associated with abortion “may, in part, be attributable to confounding variables that weren’t controlled for. Income wasn’t controlled for, and as you can see in the table itself, it might make a difference; neither was obesity.” But the details of the statistical methodology—which Cosh either missed or chose to ignore—explain clearly why these potentially confounding variables were not used to adjust the data in the table.
The experts who do say what Cosh likes are from the US National Cancer Institute (NCI; a government agency of the US Federal executive branch), so he picks out an excerpt from the NCI website that belittles retrospective, questionnaire-based studies like the new Seattle study (like most epidemiological studies, actually) claiming: “Most of these studies, however, were flawed in a number of ways that can lead to unreliable results.”
Abortion and Breast Cancer: Colby Cosh’s Continuing Confusion
Colby Cosh, in commenting (Maclean’s Online, Jan. 12) on a recent epidemiological study from Seattle, Washington which resurrects claims of a link between abortion and breast cancer (ABC link), clearly thinks this is much ado about nothing, amounting to “what pro-lifers ask Santa for Christmas”, but he thinks that “science hasn’t been much help to them.”
The news Cosh minimizes surfaced in the Globe & Mail on January 8 in a piece by Gloria Galloway. Of Galloway’s piece, Cosh selectively quotes the part which belittles an ABC link advocate, a US breast cancer surgeon and President of the Breast Cancer Prevention Institute, in claiming “that the doctor, Angela Lanfranchi, was speaking from a defined religious point of view that had little apparent basis in science.”
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