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May 11, 2008

Myth: Abortion Causes Breast Cancer

Abortion Myth #1:

Abortion Causes Breast Cancer

Depending on what state you live in, if you find yourself in need of an abortion you may very well be sat down to discuss the potential health risks associated, which is all fine and well... except when those 'health risks' aren't actual risks at all. In some states, these 'informed consent' policies include informing the patient that abortion may cause breast cancer.

The only problem? It doesn't. Abortion does not cause breast cancer. Numerous studies have proven that there is no causal relationship between abortion and breast cancer.

Whether or not there is an association or link between abortion and risk of breast cancer is still being debated - although so far the experts are leaning towards 'no'. Even if there is an as yet undetermined link, that still does not support the claims that abortion causes breast cancer.

There may be some small legitimacy to the Abortion-Breast Cancer Link (or "ABC Link") hypothesis but the facts are often twisted by anti-choice groups to support unproven theories. If you do a Google search for "Abortion and Breast Cancer" you will find a slew of websites insisting that there is a non-refuted connection between terminating a pregnancy and developing breast cancer, however this theory is far from universally accepted. Many of the studies that do alleged show evidence of a link are outdated, heavily flawed or are simply being misinterpreted.


We will be linking to a lot of sources here - while many are unbiased, scientific or news sources please be advised that some of them have a pro-choice slant, while others have a pro-life bias. Please consider where you're getting your information from, before you accept it as 'fact' and please be advised that we do not necessarily advocate or condone the information you may find once you leave our page.

Medical Theories

One theory that people use to support the ABC Link is the evidence that delaying the birth of a first child can increase the risk of developing breast cancer. Experts on both sides of the debate agree on this:

Delaying Birth of First Child
Women who have not had children, or who had their first child after age 30, have a slightly higher risk of breast cancer. Being pregnant more than once and at an early age reduces breast cancer risk. [American Cancer Society]
Having a child before age 30 years may provide some protection, and having no children may increase the risk for developing breast cancer. [eMedicineHealth.com]
Women who do not have any children have an increased risk of breast cancer. And the younger you are when you have your first child, the lower your risk of breast cancer. [Cancer Research UK]

If your first full-term pregnancy occurs after age 30, or you never become pregnant, you have a greater chance of developing breast cancer. Although it's not entirely clear why, an early first pregnancy may protect breast tissue from developing genetic mutations that result from estrogen exposure. [Mayo Clinic]

The older a woman is when she has her first child, the greater her chance of breast cancer. ...Women who never had children are at an increased risk of breast cancer. [MedicineNet.com]
A delayed first full term pregnancy increases her risk because it extends the length of time during which her breasts remain susceptible to carcinogens. Scientists define an early first full term pregnancy as one that takes place before age 24. [Coalition on Abortion/Breast Cancer]
There is also evidence that breastfeeding slightly lowers the risks of breast cancer as well, which only further supports the theory that having children - particularly having them 'early' - helps prevent breast cancer.
Statistically, if you breastfeed (particularly if you have your children when you are younger) you are at less risk of developing breast cancer. The longer you breastfeed your baby, the more you lower your risk. We don't know exactly why this is. It may be because you don't ovulate so often when you are breastfeeding. Or because breastfeeding changes the cells in the breast and may make them more resistant to the changes that lead to cancer. [Cancer Research UK]
Some studies have shown that breast-feeding slightly lowers breast cancer risk, especially if the breast-feeding lasts 1½ to 2 years. This could be because breast-feeding lowers a woman’s total number of menstrual periods, as does pregnancy. One study found that having more children and breast-feeding longer could reduce the risk of breast cancer by half. [American Cancer Society]
"How Breastfeeding Affects a Mother," describes some of the physical benefits of breastfeeding for the mother such as reduced rates of breast cancer and ovarian cancer. [La Leche League International]
However, interpreting all of that information in a way that suggests abortion (or miscarriage) causes breast cancer is unfair. If you do accept that delaying your first born increases your risk of breast cancer as fact, that still does not differentiate between a woman terminating a pregnancy, a woman having an accidental miscarriage, a woman who has chosen not to become pregnant, and a woman who wishes to become pregnant but cannot.

The anti-choicers are reaching if they make the leap from"having a baby reduces the risk of breast cancer" to "having an abortion increases the risk of breast cancer". It is technically true that if you terminate a pregnancy, you will not receive that extra 'protection' against breast cancer that having a child provides... however you will likely be no worse off than if you hadn't become pregnant in the first place.

Change in Hormones and Breast Tissue

Another hypothesis - one that has not been medically proven - is that starting a pregnancy but not carrying the fetus to term has an effect on breast tissue. A woman's risk of developing breast cancer is related to hormone levels in her body. Hormones (such as estrogen, progesterone, and prolactin) usually cause breast cells to grow and divide and these levels can change a great deal during pregnancy. This theory suggests that the high levels of estrogen produced during pregnancy cause a woman's cancer-vulnerable breast lobules to multiply but as the pregnancy continues and other hormones are produced, these lobules mature into cancer-resistant lobules. Those who support this theory believe that by terminating the pregnancy (interrupting the normal cycle of pregnancy hormones) before those lobules mature, leaves a woman with more cancer-vulnerable tissue than before she became pregnant.

This theory seems like it makes some sense and would lead one to assume that miscarriage also causes breast cancer. However, the evidence just doesn't match up. Medical studies have determined that neither abortion nor miscarriage has an effect on breast cancer risk.
Pregnancy termination, or abortion, has been looked into in several different studies. It doesn't seem to increase breast cancer risk. Researchers thought it might, because of the effect of pregnancy on breast cells. [Cancer Research UK]

...neither induced nor spontaneous abortion was associated with the incidence of breast cancer; number of abortions, age at abortion, parity status, or timing of abortion with respect to a full-term pregnancy did not affect the results. [Archives of Internal Medicine]

Large, well-designed studies have shown no link between abortion or miscarriage and breast cancer. [MedicineNet.com]
Several studies show that induced abortions do not increase the risk of breast cancer. Also, there is no evidence to show a direct link between miscarriages and breast cancer. [American Cancer Society]

Research studies ... have not found a cause-and-effect relationship between abortion and breast cancer. [American Cancer Society].

Our findings indicate that induced abortion does not increase breast cancer risk in African-American women. [Cancer Causes and Control]

In February 2003, the
National Cancer Institute (NCI) convened a workshop of over 100 of the world’s leading experts who study pregnancy and breast cancer risk. Workshop participants reviewed existing population-based, clinical, and animal studies on the relationship between pregnancy and breast cancer risk, including studies of induced and spontaneous abortions. They concluded that having an abortion or miscarriage does not increase a woman’s subsequent risk of developing breast cancer. [National Cancer Institute]

...the totality of worldwide epidemiological evidence indicates that pregnancies ending as either spontaneous or induced abortions do not have adverse effects on women's subsequent risk of developing breast cancer. [The Collaborative Group on Hormonal Factors in Breast Cancer]

There is no evidence supporting a causal link between induced abortion and subsequent development of breast cancer... ACOG's review of the research on a link between abortion and later development of breast cancer concluded that studies on the issue were inconsistent and difficult to interpret, mainly due to study design flaws. Some studies showed either a significant decrease in breast cancer risk after abortion or found no effect. The most recent studies from China, the United Kingdom, and the US found no effect of induced abortion on breast cancer risk. [The American College of Obstetricians and Gynecologists]

British researchers reviewed studies involving 83,000 women and found that pregnancies ending in abortion or miscarriage (also known as spontaneous abortion) do not significantly affect a woman's risk of developing breast cancer. ..."Overall, we found quite clear evidence that there's no increased risk of breast cancer from either miscarriage or abortion." [WebMD]

...there is no convincing evidence of a direct relationship between breast cancer and either induced or spontaneous abortion. ["Hormonal Contraception and Breast Cancer: Convincing New Conclusions (PATH, Vol. 15, No. 1)]

No causal relationship between abortion and breast cancer has been scientifically established. [National Abortion Federation]

The results from many of the early studies on the relationships between abortion and breast cancer indicated that abortions do not cause breast cancer. Although some of these early studies did suggest an association, these results were questioned due to problems inherent in the design of the studies. [Center for Reproductive Rights]

Biased or Inaccurate Research Findings

We don't deny that some of the organizations declaring that abortion does not cause breast cancer, have a pro-choice slant, but typically the mainstream, neutral medical groups agree with this claim.

However many of the groups that support the ABC Link claim often have an anti-choice bias. According to the Coalition on Abortion/Breast Cancer, the following medical groups "recognize" the link between abortion and breast cancer. See if
you can "recognize" what their biases might be...

Sources With an Agenda
  • American Association of Pro-Life Obstetricians and Gynecologists, Holland, MI. (Pro-Life).
  • Catholic Medical Association, Washington, DC. (Catholic).
  • National Physicians Center for Family Resources, Birmingham, AL. (Looks straightforward enough, but upon investigation of their website, you can find a list of the "medically responsible" policy issues they promote, which includes Abstinence-Only Sex Education).
  • Breast Cancer Prevention Institute, Poughkeepsie, NY. (This is another one that looks and seems like a straightforward medical resource. However, we took a look at their prevention fact sheet and noticed that every article listed on their 'fact sheet' was about the link between abortion and breast cancer. If this was a legitimate 'prevention institute' wouldn't they mention other methods of prevention and other risk factors?)
  • The Polycarp Resarch Institute, Altoona, PA. (Their website overview mentions that they will "support research effort that improve the spiritual condition of men and women, and will not promote methods or intentions that are inconsistent with the ethical and moral guidelines of the Catholic Church").
  • Ethics and Medics, Philadelphia, PA. (Ethics and Medics is a periodical provided by the National Catholic Bioethics Center).
  • MaterCare International, St. John's, Newfoundland, Canada. (MCI is an association of Catholic Obstetricians and Gynaecologists "dedicated to improving the lives and health of mothers and their children both unborn and born throughout the word, through new initiatives of service, training, research, and advocacy, in accordance with the contemporary teaching contained in the Gospel of Life of the late Pope John Paul II and reiterated in the first Encyclical of Pope Benedict XVI").
  • B.R.E.A.S.T Care Center, Quezon City, Philippines. (Their organization seems to legitimately be concerned with women's health and devoted to breast cancer research and care. However, we do think it's important to remember the social climate in the Philippines in regards to abortion. Abortion is illegal, the government promotes 'natural family planning' only and they have one of the highest rates of unsafe abortions in Asia).
Now this isn't to say that the information presented or "recognized" by these organizations is necessarily untrue, just because they're anti-abortion. It is just important to realize where your 'facts' are coming from and take that bias into consideration (whether it is a conscious bias or not).

The Coalition also lists groups that are "in need of political courage", which we suppose means that they need to 'admit' that abortion causes breast cancer? They list mainstream groups such as the Royal College of Obstetrics and Gynecologists, the American College of Obstetricians and Gynecologists, the American Medical Association, the American Society of Breast Surgeons, etc. all of whom apparently do not support the ABC Link theory.

Studies on this subject haven't always been easy to conduct which likely explains why some of the earlier evidence suggested the possibility of an association between breast cancer and abortion. However, later - more accurate - methods of research have helped medical experts dispute the ABC Link theory.
Abortion was - and usually still is - a very personal and private subject. Therefore women do not always properly and honestly disclose their complete medical histories when it comes to abortion. Women who have had abortions - especially those who had illegal abortions before Roe v. Wade - might not always feel comfortable disclosing this information. Additionally, healthy women are less likely to report their histories of abortion than those with medical problems (this has been determined by numerous studies but also is just common sense!)

Women with breast cancer are much more likely to report their reproductive histories accurately. In many cases they are wracking their brains, trying to come up with any possible incident from the past that might have contributed to their cancer. False responses due to 'recall biases' such as these, have likely undermined the accuracy of the results of many studies on the alleged ABC Link.

Research Flaws and Problems
Recent research has confirmed that the type of study likely plays a role in what is found. A review of the previous studies on this issue, covering tens of thousands of women, showed that women followed in prospective studies (which are less prone to bias) had no increased breast cancer risk if they had had an abortion. Retrospective (case-control) studies, on the other hand, pointed to a slight increase in risk.

...Most early studies of abortion and breast cancer used a
case-control study design, one that is very prone to recall bias. In these studies, women with and without breast cancer were asked to report past abortions. The researchers then compared the frequency of abortions in women with breast cancer (the "cases") to those in women without breast cancer (the "controls"). It is likely that the higher rates of reported abortions in breast cancer cases (vs. controls) observed in many of these studies were not true findings because of recall bias.
A prospective (cohort) study design is stronger and less prone to bias. In this type of study, a group of women who are cancer-free are asked about their past abortions and then are observed over a period of time to see if a new cancer occurs. In this type of study all of the women are cancer-free at the start, so there is no chance that having the disease will influence their memory of past abortions or willingness to report past abortions. [American Cancer Society]

Available data are inconsistent and inconclusive, with some studies indicating small elevations in risk, and others showing no risk associated with either induced or spontaneous abortions. The scientific rationale for an association between abortion and breast cancer is based on limited experimental data in rats, and is not consistent with human data.

Studies that have attempted to evaluate the association between abortion and breast cancer have been limited by small numbers of study subjects, questions of comparability between the study groups, inability to separate induced abortions and spontaneous abortions, and incomplete knowledge of other potentially pertinent lifestyle factors. Perhaps the most serious potential weakness relates to the possible inaccuracy of reporting of abortions by study participants.

Indeed, results from a study that examined the accuracy of reporting abortions indicate that women with breast cancer are more likely to accurately report having had an abortion than women without breast cancer, possibly leading to a false association between abortion and breast cancer. ["Hormonal Contraception and Breast Cancer: Convincing New Conclusions" (PATH, Vol. 15, No. 1)]

Researchers say previous studies that suggested having an abortion slightly increases a woman's risk of breast cancer were flawed because they were based on women reporting having had an abortion after a diagnosis of breast cancer, known as a retrospective study.

..."Studies can give misleading results if women are asked about previous abortions only after they are diagnosed with breast cancer," WebMD]

Early studies of breast cancer raised substantial concern regarding risk associated with induced abortion and miscarriage. Literature reviews suggest that study findings depend heavily on the comparison group and that the use of parous [having given birth] women as a reference group for nulliparous [never having borne a child] women may artificially inflate risk. ["Induced Abortion, Miscarriage, and Breast Cancer Risk of Young Women" (Cancer Epidemiology, Biomarkers & Prevention)]
It is also important to remember that one single study suggesting a link between two 'events' (in this case, having an abortion and developing breast cancer) does not by itself prove that the first event caused the second event. There are often unknown factors and sometimes it just boils down to coincidence. You cannot base a 'fact' on circumstantial evidence.

There are many outdated studies that the anti-abortion activists use to support their claim that abortion causes breast cancer, but more recent and thorough research has disproved this theory.

There may be some evidence that abortion actually decreases the risk of breast cancer. Of course, there isn't enough data for any medical authority to make that claim, however it helps to refute the ABC Link theory.

Possible Benefits of Abortion?

One of the largest and most well-known studies on abortion and breast cancer was done in Denmark in the 1990s. Instead of relying on solely on interviews, which can be undermined by false responses, the bulk of the study was done based on information on more than 1.5 million women from the Danish Cancer Registry and the National Registry of Induced Abortions. Denmark keeps very detailed medical records, including history of abortion (which is legal and free).

After adjusting for other known breast cancer risk factors, the research found that women who had an abortion - even two or more - had no increased risk of developing breast cancer. (Women who had abortions prior to seven weeks of pregnancy seemed to have a slightly lower risk of breast cancer, however the number of women in that category was too small to make any conclusive claims).

In a study funded by Cancer Research UK, researchers compared the risk of breast cancer in women after having an abortion or miscarriage with that of women who had never been pregnant. Based on the data from 44,000 women, they found that women who had a pregnancy that ending in induced abortion or 'spontaneous abortion' (miscarriage) had no increase in breast cancer risk. Women who had an abortion actually had a slightly lower risk of breast cancer (7% decrease).

According the the authors of "Induced Abortion, Miscarriage, and Breast Cancer Risk of Young Women" (Cancer Epidemiology, Biomarkers & Prevention) among women who had never borne children, the breast cancer risk was reduced in those who had abortion as compared with those who had never been pregnant (and the risk declined as the number of induced abortions increased). Although they did state that the risk estimate was "imprecise".

Even if they were to prove that abortion reduces the risk of breast cancer - which they have not proven - we would never in any waysuggest that abortion is an effective or practical means of preventing breast cancer. We just don't believe that carrying a pregnancy to term and having a child that you're not able raise is an effective means of cancer prevention either.

The Bottom Line

The bulk of the recent scientific evidence points to the conclusion that abortion does not cause breast cancer, nor does it increase the risk of developing breast cancer. Despite the strong consensus, anti-choice organizations are still adamant about the claim that abortion causes breast cancer. They portray this theory (that has little scientific basis) as 'fact' in order to appear as though they care about women's health. The truth is, they're just trying to scare women from exercising their legal right to choose.

Anti-choice forces are even willing to intrude upon the doctor-patient relationship. Several states have enacted laws mandating the discussion of an increased risk of breast cancer as a risk of abortion. Such laws force doctors to choose between misleading their patients and obeying the law. [National Abortion Federation]
For information on the actual risks and preventions of breast cancer: American Cancer Society.

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