Abortion and Breast Cancer:
Recall Bias


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A number of studies have found a link between abortion and breast cancer. To date 22 studies have been published in medical journals, of which 17 find a link.

It is true that in half these studies, the results were not conclusive. The number of women included who had abortions and who contracted breast cancer was not large enough to be sure that the results found were not simply coincidence. But twelve of the studies did give statistically significant results, and of these, eleven found that there was a connection and one found that there was not.

For the most part, pro-abortion activists have simply ignored or downplayed these results. Some have said that the one study finding no connection has "proven" that the eleven which found a connection must be mistaken. Case closed.

A more substantive rebuttal is that these studies suffer from "recall bias". According to this theory, the studies are flawed because they rely on women's self-reporting about whether they have had abortions. Women may not want to admit that they have had abortions, or they may have forgotten until a health problem brings the abortion back to mind.

There are several objections one could make to this theory.

  1. It seems very unlikely that a woman would forget that she has had an abortion. Pro-abortionists routinely say that a woman would never have an abortion without deep soul-searching, consulting with her pastor or priest, etc etc.

    Therefore, we must conclude that the vast majority of these women are, in fact, simply lying. This too is a troubling claim. We must believe that middle-aged black women, in particular, are incredible liars, as a study published in the Journal of the National Medical Association (December 1993) found that black women of age 50 and older who had one or more induced abortions had an increased cancer risk of 370%. To claim that this result is entirely due to consistent lying on the part of black women sounds rather racist to me.

  2. Studies done with animals have found similar results to human studies. In a study published in the American Journal of Pathology (August 1980, pp 497-511), researchers performed abortions on rats and then compared their breast cancer rates to a control group. They found that the aborted rats had fourteen times the breast cancer rate as rats who had carried their pregnancies to term. It seems fair to suppose that this study could not have suffered from "recall bias", as the researchers did not interview the rats.

  3. At least one (human) study, published in the International Journal of Epidemiology (1989, Dr. Holly Howe, et al, pp 300-304), did not rely on interviews. Instead they used New York databases of induced abortion and breast cancer. They found the overall risk of breast cancer from induced abortion was an increase of 90%.


A side note: One could ask whether pro-choice people are really as "pro-choice" and "pro-woman" as they claim, or whether they are, in fact, truly "pro-abortion". If they really cared about choice, wouldn't they want women to have as much information as possible, so they could make a truly informed choice? If they really cared about women, wouldn't they warn them about possible adverse health effects, even if they honestly believed the danger to be uncertain? Products have been pulled from the shelves on much less evidence than the present case about the abortion / breast-cancer link.


Most of the information for this article came from
Cancer Awareness Canada | 810 W. Broadway (651) | Vancouver, BC, Canada V5Z 4C9


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Posted 9 Sep 2000.

Copyright1996 by Ohio Right to Life.
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