Abortion and Breast Cancer: An Evidence Based Perspective

Position Paper 70 Abortion Rights Coalition of Canada June 2005

Abortion and Breast Cancer: An Evidence-Based Perspective

All women have the right to be presented with pregnancy options in a non-judgemental, unbiased manner. Bias, misinformation, and coercion are a violation of the fundamental rights of all women. The anti-choice movement commonly uses misinformation to scare women out of having abortions. Of the many false statements presented as fact, one of the most common is the purported link between breast cancer and therepeutic abortion. However after evaluating current, reliable evidence on the subject, ARCC, in agreement with the vast majority of all reputable medical associations, believes that there is no link between therepeutic abortion and the development of breast cancer.

What do Current Scientific Studies and Medical Associations Say About The Link Between Abortion and Breast Cancer?

Determining whether there is a link between abortion and breast cancer(ABC) has been the subject of extensive scientific research. The anti-choice movement is able to manipulate some data because literature prior to the 1990s was largely inconsistent- many studies have serious
methodological flaws(small sample size, insufficient controls for variability, researcher bias). More contemporary studies, which corrected the above mentioned methodological flaws, show that there is no demonstrable link between therepeutic abortions and breast cancer; there is neither an increase nor decrease in breast cancer among women who have had a therepeutic abortion(for specific references, please consult the endnotes).

Perhaps the most significant evidence refuting the ABC link comes from the National Cancer Institute (NCI) in the United States. In 2002, the NCI posted a report on its website dispelling myths about ABC. When this report was criticised by anti-choice members of Congress, the NCI held a conference, 'Early Reproductive Events and Breast Cancer' in 2003 in Bethesda, MD. This conference brought together 100 cancer experts and epidemiologists to examine the data and provide a clear statement of fact. Their conclusion was that it is well established that induced abortion[a.k.a therepeutic abortion] is not associated with an increased risk of breast cancer.

Several other organisations have also produced position statements with regards to the so-called ABC link. The Society of Obstetricians and Gynaecologists of Canada and the Society of Gynecologic Oncologists of Canada released a joint committee opinion statement in May 2005, which maintains there is no link between either spontaneous abortion(miscarriage) or therepeutic abortion and the increased risk of breast cancer. The American College of Obstetricians and Gynaecologists Committee on Gynecologic Practice released an opinion statement in August 2003, with the finding that early studies demonstrating an ABC link were inconclusive, and that more recent studies argue against a link between abortion and breast cancer. The Canadian Cancer Society, which monitors risk factors as they pertain to cancers, agree with the NCI findings that there is no association between abortion and breast cancer.

What About Advertising That States That There is a Link Between Abortion and Breast Cancer?

Data that claims to support a link between abortion and breast cancer is highly biased. First, those who advertise an ABC link are connected to organisations with the primary goal of restricting abortion, not reducing rates of breast cancer. Second, the few studies that suggest an ABC link are now considered to be out-of-date, and were not of a particularly high standard to begin with. These studies took sample sizes that were too small (i.e. small sample sizes are not representative of the whole population), and relied on patient recall rather than following people over a period of time.

Conclusion

Unfortunately, it is all too easy to pas off false information as fact. Anyone can make a website that looks professional, and anyone can write a press release. When faced with any piece of information, especially something with far-reaching consequences, it is important to be vigilant in questionng the source of such statements.
There are a few simple ways to do this:

1. Look for references. The best references come from good, peer reviewed journals. If the information is important enough, and is sound, it will get into a good journal.
2. Look at the age of the resources. Information changes over time as we learn more and more about a topic.
3. Check the affiliations of the organisations and researchers doing the studies.
4. Beware of personal opinions. They are just that- opinions not fact.

Sources

Brewster DH et al. 'Risk of Breast Cancer after miscarriage or induced abortion: a Scottish record linkage case-control study' J Epidemiol Community Health 2005; 59; 283-287

Canadian Cancer Society. 'Abortion and Breast Cancer' Accessed Online October 1, 2005 at: http://cancer.ca/ccs/internet/standard/0,2704,3172_369425_langId-en,00.html

Collaborative Group on Hormonal Factors in Breast Cancer. 'Breast Cancer and Abortion: Collaborative reanalysis of data from 53 epidemiological studies, including 83,000 women with breast cancer from 16 countries'. Lancet 2004; 363; 1007-16.

Committee on Gynecologic Practice, American College of Obstetricians and Gynaecologists. 'ACOG committee opinion. Induced abortion and breast cancer risk. Number 285, August 2003.' Int J Gynaecol Obstet. 2003 Nov;83(2);233-5.

Erlandsson G, Montgomery SM, Chattingius S, Elkborn A. 'Aboritons and breast cancer' Int J Cancer 2003; 103(5);676-9.

Lash TL, Fink AK. 'Null association between pregnancy termination and breast cancer in a registry-based study of parous women'. Int J Cancer 2004; 110; 443-448.

Mahue-Giangreco M, Ursin G, Sullivan-Halley J, Bernstein L. 'Induced Abortion, Miscarriage, and Breast Cancer Risk of Young Women' Cancer Epidemiology, Biomarkers and Prevention 2003; 12; 209-214.

National Cancer Institute. 'Summary Report: Early Reproductive Events and Breast Cancer Workshop'. Accessed online October 1, 2005 at: http://www.cancer.gov/cancerinfo/ere-workshop-report-report

Paoletti X, Clavel-Chapelon F. 'Induced and Spontaneous abortion and breast cancer risk: results from the E3N cohort study' Int J Cancer 2003: 106(2); 270-6.

Society of Obstetricians and Gynaecologists of Canada/ Society of Gynegologic Oncologists of Canada. 'Breast Cancer and Abortion', JOGC 2005; 27(5); 491.

Ye Z, et al. 'Breast cancer in relation to induced abortions in a cohort of Chinese women.' Br J Cancer 2002; 87; 977-981.