The Correlation Between Abortion and Breast Cancer: Real or Hoax?

  • William Lawyer
  • 10/16/2020

Pro-choice advocates often criticize pro-life organizations (which support pregnant women and their children) as spreading what pro-choice advocates view as false or misleading information about abortion and women's health.

In particular, pro-choice advocates often point to information about abortion and breast cancer provided by some pro-life organizations as an example of such misinformation. Medical organizations and health clinics providing care and support for pregnant women that discuss even the potential of such a link are often referred to by pro-choice groups as fake clinics, and are viciously attacked as being intentionally deceitful and ill-intentioned. Indeed, the claim that some groups were providing such information has even been used to justify passing laws targeting pregnancy resource and care centers.

However, despite how often pro-life groups are attacked for providing information about a link between abortion and breast cancer, little care seems to have been given to ensure that this information is actually wrong.

The "Pro-Life" Science

In fact, a large volume of research indicates that abortion can indeed cause breast cancer. Countless studies have demonstrated that women with a history of abortion had significantly increased risks of breast cancer compared to women who complete their pregnancy or who have never been pregnant, and have provided sound reasoning for why abortion would increase one’s risk.

Among breast cancer researchers, it is a generally accepted theory that the completion of pregnancy itself helps decrease the risk of breast cancer. Exposure to the pregnancy hormones is required for breast cells to complete the differentiation, which is crucial for the lowered susceptibility of breast cells to carcinogenesis in a woman's later life. The process of differentiation, however, can be easily interrupted by abortions, not only preventing that protective effect, but potentially increasing one’s risk of breast cancer as well.(1)(2)(3)

Studies on abortion and breast cancer have time and time again demonstrated that this increased risk is present, but they don’t always agree on how significant its impact is. The estimated magnitude of the increase in this risk varies widely across the body of research that has been done on the subject, but most research does demonstrate that the increased risk is there. 

One study published in the Journal of the National Cancer Institute, for example, found that, among women who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women, while a similar examination from the American Journal of Epidemiology found only about a 20%–40% increase in the risk of breast cancer related to induced abortion. Other research from The Journal of the American Medical Association and Cancer Causes & Control examining multiple states, China, and seven other countries have found increased risk rates ranging from a little over 20% to as high as 90% or more.(4)(5)(6)(7)(8)

While it’s hard to gauge just how great the increase in risk might be, an extensive and comprehensive review and meta-analysis of dozens of studies on this subject found that the research, on the whole, suggests that abortion may cause thousands of excess cases of breast cancer every single year.(9)

The "Pro-Choice" Science

Pro-choice advocates have, in response to these studies, argued that all research showing a link between abortion and breast cancer is inaccurate and suffers from recall bias, the idea that women who have breast cancer are more likely to report abortions than healthy women. Instead, they point to studies such as those published in The New England Journal of Medicine and Cancer Causes & Control examining abortion and breast cancer among Danish and African-American women which concluded that induced abortion did not increase breast cancer risk, and posit that women who develop breast cancer might be more likely to disclose abortions, creating the link so clearly observed in other research.(10)(11)

The Problem with the "Pro-Choice" Science

While the existence of such contradictory studies is significant, other research demonstrated that they and the arguments used to discredit the body of studies showing a link between abortion and breast cancer are largely baseless.

As an example, extensive and comprehensive research in Issues in Law and Medicine exhaustively examined many of the biases and problems found in studies of breast cancer and abortion, devoting particular attention to the idea of recall and reporting bias. Ultimately, the research found little evidence that recall bias was significantly throwing off the results of most studies on abortion and breast cancer, and concluded that the dismissal of such research and retrospective data on those grounds was scientifically unjustifiable.

Moreover, the analysis found that while no study was without its flaws, most of those that didn’t find a link between abortion and breast cancer tended to be particularly poorly designed. In addition to exhaustively analyzing a number of other abortion-breast cancer-related subjects, their research also found that the developmental biology of the breast strongly supports the idea of a link between induced abortion and breast cancer.(12)

Even if recall bias is a reasonable justification for the dismissal of other studies indicating a link between abortion and breast cancer, however, it is in no way applicable to the whole body of research on the subject. Record linkage research, research that would not be subject to recall bias or reporting bias, has also found massively increased risks of breast cancer among those who received an induced abortion, nearly doubling their risk of developing breast cancer.(13)

An Honest Conclusion

It seems that neither pro-life advocates nor pro-choice advocates are spreading misinformation about abortion and breast cancer, at least not intentionally so. Both have reasons for believing what they do and are generally basing their beliefs upon at least some scholarly research. 

But both can’t be right.

While many will still claim that pro-life advocates are spreading misinformation if and when we discuss these issues, the fact is that the bulk and best of the research we have available on the subject indicates that there is indeed a link between abortion and breast cancer, and that abortion is massively contributing to breast cancer incidence around the world. 

If we truly want to provide factual information to women, it is only right that we, at the very least, acknowledge that such a connection may exist. Rather than misleading women and downplaying the potential risks of abortion, they should be given accurate information about what they are choosing to do. This is why so many pro-life groups continue to provide this information, despite the vicious attacks doing so subjects them to.

Here at Pro-Life Utah, we do everything we can to bring both facts and love to the issue of abortion. Please consider making a donation so we can keep bringing you articles like these. Or, to learn more about other ways we are shedding light on the subject, read about our new Ultrasound Van.

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1. Clinical and epidemiologic factors associated with breast cancer and its subtypes among Northeast Chinese women

(Cancer Medicine, Volume 8, Issue 17, October 2019)

-Dong?Man Ye, Qiang Li, Tao Yu, Hao?Tian Wang, Ya?Hong Luo, Wen?Qing Li

2. Susceptibility of the mammary gland to carcinogenesis. II. Pregnancy interruption as a risk factor in tumor incidence - (PDF)

(American Journal of Pathology, Volume 100, Issue 2, August 1980)

-José Russo, Irma Russo

3. The short-term and long-term effect of a pregnancy on breast cancer risk: a prospective study of 802,457 parous Norwegian women

(British Journal of Cancer, Volume 72, Issue 2, July 1995)

-Gunnar Kvåle, Ivar Heuch, Grethe Albrektsen

4. Risk of Breast Cancer Among Young Women: Relationship to Induced Abortion | JNCI: Journal of the National Cancer Institute | Oxford Academic

(Journal of the National Cancer Institute, Volume 86, Issue 21, November 1994)

- Janet R. Daling, Kathleen E. Malone, Lynda F. Voigt, Emily White, Noel S. Weiss

5. Risk of Breast Cancer among White Women following Induced Abortion | American Journal of Epidemiology | Oxford Academic - (PDF)

(American Journal of Epidemiology, Volume 144, Issue 4, 15 August 1996)

-Janet R. Daling, Louise A. Brinton, Lynda F. Voigt, Noel S. Weiss, Ralph J. Crates, Kathleen E. Malone, Janet B. Schoenberg, Marilie Gammon

6. Pregnancy Termination in Relation to Risk of Breast Cancer

(The Journal of the American Medical Association, Volume 275, Issue 4, 24 January 1996)

-Polly A. Newcomb, Barry E. Storer, Matthew P. Longnecker, Robert Mittendorf, E. Robert Greenberg, Walter C. Willett

7. A meta-analysis of the association between induced abortion and breast cancer risk among Chinese females - (PDF)

(Cancer Causes & Control, Volume 25, Issue 2, February 2014)

-Yubei Huang, Xiaoliang Zhang, Weiqin Li, Fengju Song, Hongji Dai, Jing Wang, Ying Gao, Xueou Liu, Chuan Chen, Ye Yan, Yaogang Wang, Kexin Chen

8. Abortion and breast cancer risk in seven countries

(Cancer Causes & Control, Volume 6, Issue 1, January 1995)

-Karin B. Michels, Chung-cheng Hsieh, Dimitrios Trichopoulos, Walter C. Willett

9. Induced abortion as an independent risk factor for breast cancer: a comprehensive review and meta-analysis - NCBI - (PDF)
(Journal of Epidemiology and Community Health, October, 1996)

- Joel Brind, Vernon M Chinchilli, Walter B Severs, Joan Summy-Long

10. Induced Abortion and the Risk of Breast Cancer | NEJM

(The New England Journal of Medicine, January 1997)

-Mads Melbye, Jan Wohlfahrt, Jørgen H. Olsen, Morten Frisch, Tine Westergaard, Karin Helweg-Larsen, Per Kragh Andersen

11. A prospective study of induced abortion and breast cancer in African-American women

(Cancer Causes & Control, Volume 15, Issue 2, March 2004)

-Julie R. Palmer, Lauren A. Wise, Lucile L. Adams-Campbell, Lynn Rosenberg

12. Breast Cancer and Induced Abortion: A Comprehensive Review of Breast Development and Pathophysiology, the Epidemiologic Literature, and Proposal for Creation of Databanks to Elucidate All Breast Cancer Risk Factor- PubMed - NCBI - (PDF

(National Center for Biotechnology Information, Issues Law Med, Spring, 2014)

- Angela E. Lanfranchi, Patrick Fagan

13. Early Abortion and Breast Cancer Risk among Women under Age 40

(International Journal of Epidemiology, Volume 18, Issue 2, June 1989)

-Holly L. Howe, Ruby T. Senie, Helen Bzduch, Peter Herzfeld

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