Abortion - Breast Cancer link?

Pro-life studies; agencies'
statements; conclusions

Pro-life meta-analysis of existing studies:

In 1996-OCT, Dr. Brind and three other US scientists announced the result of a statistical analysis of previous studies. ₁ They selected 23 studies which involved over 60,000 women. They combined all of their results using a process known as "meta-analysis." They found "overwhelming" evidence that women who terminate a pregnancy by an abortion have a 1/3 higher chance of contracting breast cancer later in life. This particular statistical method is fraught with hazards, because the results can easily be influenced by the method used when selecting which specific studies are included.

Three of the four scientists in the 1996-OCT study are known to have been vocal opponents of abortion. They might have been biased, consciously or unconsciously, in their selection processes. Most or all of the studies selected were case control studies, and thus were not reliable.

Conclusions reached by health advocacy agencies:

Major groups concerned with health have all concluded that a link between breast cancer and abortion has not been established, including:

"It has been hypothesized that surgical and spontaneous abortions increase breast cancer risk. However, the largest and most reliable research studies show that there is no association between either kind of abortion and risk of breast cancer. Based on overwhelming scientific evidence, NBCC does not support any public policy efforts that imply such a link exists." ₂

"Several studies have provided very strong data that induced abortions have no overall effect on the risk of breast cancer. Also, there is no evidence of a direct relationship between breast cancer and spontaneous abortion (miscarriage) in most of the studies that have been published. Scientists invited to participate in a conference on abortion and breast cancer by the National Cancer Institute (February 2003) concluded that there was no relationship. A recent report of 83,000 women with breast cancer found no link to a previous abortion, either spontaneous (stillbirth) or induced." ₃

"Most of the information on whether induced abortion modifies the risk of breast cancer among women comes from epidemiological studies, which are either case-control studies, or historical cohort studies. For information on abortion, all published case-control studies have relied on interviews of cases and controls with the inherent problem of recall bias. This bias occurs because women with breast cancer (cases) tend to truthfully report induced abortion while controls, who often are healthy women, have no "incentive" to provide information about personal and sensitive matters such as induced abortion. Such bias can produce elevated relative risk estimates in case-control studies. As a result, the outcome of such studies has been inconsistent, with some having indicated a small increase in risk, while others have not."

"Historical cohort studies, on the other hand, are more methodologically sound. Two major studies have been carried out using this methodology, and neither found an increased risk of breast cancer associated with first trimester abortion."

"Therefore, results from epidemiological studies are reassuring in that they show no consistent effect of first trimester induced abortion upon a woman’s risk of breast cancer later in life." ₄

The National Cancer Institute has stated that "taken together, the inconsistencies and scarcity of research do not permit scientific conclusions."  According to a National Cancer Institute epidemiologist, "a woman need not worry about the risk of breast cancer when facing the difficult decision of whether to terminate a pregnancy." 5

Other groups have concluded that a link has not been established, including The American Cancer Society. The American College of Obstetricians and Gynecologists. The U. S. Department of Health and Human Services Office of Public Health and Science.  The National Breast Cancer Coalition. 5

Conclusions:

	At least one of the studies which may show an ABC link have found that late abortions may increase the risk more than early first trimester abortions. This finding is one more reason why a woman who has decided to terminate her pregnancy do it as early as possible.
	Although some studies appear to show a correlation between abortion and breast cancer, there many not be a cause-and-effect relationship between the two. Another factor, like the woman's age at first completed pregnancy, might be the actual cause.
	The Danish study of 1997 and the UK meta-study of 2004 seem to conclusively prove that no ABC link exists, other than the one described above.

References:

The following information sources were used to prepare and update the above essay. The hyperlinks are not necessarily still active today.

1. Dr. Joel Brind, "Induced abortion as an independent risk factor for breast cancer: A comprehensive Review and Meta-Analysis," Journal of Epidemiology and Community Health, 1996-OCT.
2. "Position Statement on Abortion and Breast Cancer Risk," National Breast Cancer Coalition (NBCC), 2004-NOV, at: http://www.natlbcc.org/
3. "What Are the Risk Factors for Breast Cancer?,"American Cancer Society, , at
   http://www.cancer.org/
4. "Induced Abortion Does Not Increase Breast Cancer Risk," Fact Sheet #240, World Health Organization, 2000-JUN, at http://www.who.int/
5. "Naral Factsheets: Abortion, Breast Cancer and the Misuse of Science," at: http://www.naral.org/ No longer online.

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Copyright 1998 to 2007 by Ontario Consultants on Religious Tolerance
Latest update: 2007-MAY-24
Author: B.A. Robinson

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