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Does abortion increase the risk of breast cancer?

Breast Cancer Risks and Choices

The American Cancer Society reports that one of every nine women in the United States will develop breast cancer by age 85. It has become the second major cause of cancer death in women. Many of the factors which put women at risk cannot be controlled. For example, women can't control their family history, their age or whether their menstrual cycle starts early or ends late in life. But medical researchers are now realizing that women can control some of the risk factors in getting breast cancer by the choices they make; for example, choosing to eat a diet high in broccoli and cabbage. Choosing to have a child or terminate a pregnancy can also impact on the risk of breast cancer, as there is now growing evidence that an abortion during high estrogen levels in the early months of pregnancy pre-disposes women to getting breast cancer.

Are You At Risk?
  • Older than age 40?
  • Personal history of breast cancer (already have had cancer in one breast)?
  • Personal history of benign fibrocystic breast disease"
  • Family history of breast cancer (mother, sister, aunt and/or grandmother)? Risk increases if these relatives had it in both breasts and if it occurred before menopause.
  • Never giving birth, or not giving birth until after age 30?
  • Overweight after menopause?
  • Menstrual periods started early and/or ended late in life?
  • Personal history of ovarian cancer?
  • Had a pregnancy, especially the first pregnancy, which resulted in abortion? This risk is substantially greater for women who have a family history of breast cancer, or who have had an abortion before age 18 or after age 30.

If you fall in one or more of these categories, see your doctor about breast cancer detection information. For more specific information about the link between breast cancer and abortion, read the following interview with medical researcher Dr. Joel Brind.

Joel Brind is a Professor of Biology, Chemistry and Endocrinology at Baruch College, the City University of New York. Dr. Brind earned his BS at Yale University and his Ph.D. in Basic Medical Sciences at New York University. He has been conducting research on diseases related to reproductive steroid hormones since 1972.

Q. How does abortion ultimately cause breast cancer?

A. Almost all of the risk factors which are know to increase the risk of breast cancer are associated with some kind of excess exposure to the main female sex steroid hormone, estrogen. The theory on how this works in an abortion is quite simple. The biggest surge of estrogen occurs in the first trimester of pregnancy. Estrogen goes sky high. That's okay because although it stimulates the growth of the breasts, toward the end of the pregnancy other hormones kick in that make the breast tissue mature, which also kills off cells that are not needed. Once the mature cells are (ready) to produce milk, they are not in a growing mode. Consequently they are much less likely to be subject to the mutogenic or initiating effects of carcinogens, (the substances that produce cancer). The carcinogens will affect cells which basically can grow. If you have an abortion in the first half of the pregnancy, you get all of these growth-promoting effects on the tissues because of the big surge of estrogen. Without the differentiating and maturing effects of the later hormones, the net result is the opposite of what you find in a full-term pregnancy. It's known that a full-term pregnancy early in a woman's reproductive life is protective against breast cancer. But an early abortion not only does not confer that protection but goes the other way and confers increased risk. Thus, the extra estrogen ultimately causes abnormal cells to grow into full blown cancer.

Q. Does a miscarriage (a spontaneous abortion) also confer increased breast cancer risk?

A. A number of studies have shown such a risk increase, but many others-including the largest and most recent-1,2,3 do not. Many early studies did not distinguish between spontaneous and induced abortion. Thus, the body of knowledge in this area is inconsistent. What has been consistently demonstrated is that induced abortion-the kind that is a matter of choice-does increase breast cancer risk.

Q. Why would not a spontaneous abortion (miscarriage) carry an increased risk as well as an induced abortion?

A. We are not sure yet. Spontaneous abortion is harder to measure epidemiologically and it has many causes. One reason miscarriages occur is that the surge of hormones (including estrogen) is inadequate to maintain the pregnancy. In simple terms spontaneous abortion is the natural termination of an abnormal pregnancy, whereas induced abortion is almost always the artificial termination of a normal pregnancy. Thus, they are very different events and the difference in consequences should not be too surprising.

Q. Of the women who will have abortions this year, how many cases, based on your research, will result in breast cancer?

A. Of the 800,000 women every year who get abortions and who have never had a full-term pregnancy, you are increasing the average lifetime risk among them by at least 50 percent. By the year 2020 you are going to see 40,000-50,000 breast cancer cases minimum, every single year, that are due to induced abortions.

Q. Is there any difference in the severity of the cancer because of the abortion history?

A. There are several studies which show that women who have breast cancer and who have a history of abortion not only have a greater incidence of breast cancer, but the cancer grows more rapidly, has more signs of cancers that are harder to treat, (4) is more invasive and is more aggressive. (5) The cancer comes back on average in a shorter period of time and they die more readily from the cancer. (6) So it is not only more frequent, but more severe.

Q. When a woman visits her doctor, should she inform the doctor of her history of abortion during the breast exam and ask about the added risk of breast cancer?

A. Absolutely. I know a woman who a few years ago was told by her doctor she had a benign fibrocistic lump in her breast and not to worry about prophylactic mastectomy (removal of the breast in the absence of cancer) because she wasn't really high risk. She had no family history. But she didn't have any children and she was 40 years old and she had had two abortions and a miscarriage. Now that doctor, if he knew about this added risk, would likely have said, "Well, yes, you are probably a good candidate for prophylactic mastectomy." Meanwhile, less than a year later she was diagnosed with advanced breast cancer and she had to have a radical mastectomy.

Q. What are the risk factors for someone in this category?

A. The risk of breast cancer among the general population of women is now close to 12 percent. Among women who have no children it is more like 20 percent. And among women who have no children and also have one or more abortions it's probably closer to 50/50. And an even more ominous association was uncovered by the large National Cancer Institute study published in 1994. Out of 1,800 subjects under age 45, 12 had a positive family history of breast cancer and also had an abortion before age 18. All 12 were in the breast cancer group. This the relative risk was incalculably high. (2)

Q. How will the legalization of RU 486 affect breast cancer rates based on your research?

A. Should this drug be legalized in the United States and should it result in increased frequency in induced abortions, it would substantially increase the risk of breast cancer for the simple reason that it doesn't matter how the pregnancy is terminated. Wherever it is used to induce abortion it will increase the risk of breast cancer and for every 20 childless women who take it, there will be one who will get breast cancer from it who otherwise would not have gotten it.

Inform Your Doctor

Tell your doctor how Dr. Joel Brind links the long history of peer reviewed medical research establishing the breast cancer and abortion link:

  • A 1981 Los Angeles study found a significant 2-4 fold higher incidence of breast cancer among women under 33 years of age who had had an abortion before a live birth. (7)
  • A 1989 New York State Department of Health study of all 1,451 upstate and Long Island women who developed breast cancer between 1976 and 1980 before age 40 showed a significant 90 percent risk increase among women who had ever had any abortions, and a significant 300 percent risk increase among women with two consecutive abortions. (8)
  • In 1990 Russian Epidemiologist Larissa Remennick summarized medical studies from Israel, Canada, France, Denmark, Japan, the US and the USSR and found that "abortions, either multiple or occurring before the first full term pregnancy, have been shown to be significantly associated with breast cancer risk". (9)
  • A highly significant 1993 Howard University study showed that African American women over age 50 were 4.7 times more likely to get breast cancer if they had had any abortions compared to women who had not had any abortions. (1)
  • A 1994 National Cancer Institute study of over 1,800 women in Washington state found a significant 50 percent increase risk among women who had any abortions. The risk was more than double for women whose abortion (or first abortion) took place before age 18 or over age 30. (2)
  • A 1995 Harvard University study on over 2,000 women in Greece found a significant 51 percent increased breast cancer risk among women who had any abortions. (3)

Peer Reviewed Medical Journal References
  1. Laing AE, Demenais FM, Williams R, Kissling G, Chen VW, Bonney GE, (1993), Breast Cancer Risk Factors in African American Women: The Howard University Tumor Registry Experience, J Natl. Med. Assoc., 85: 931-939.
  2. Daling JR, Malone KE, Voight LF, White E, Weiss NS, (1994), Risk of Breast Cancer Among Young Women: Relationship to Individual Abortion, J Natl. Cancer Inst., Vol. 86,pages 1584-1592.
  3. Lipworth L, Katsouyanni K, Ekbom A, Michels KB, Trichopoulos D, (1995), Abortion and the Risk of Breast Cancer; A Case Control Study in Greece, Int J Cancer, Vol. 61, pages 181-184.
  4. Olsson H, Ranstam J, Baldetorp B, Ewers S-B, Ferno M, Killander D, (1991), Proliferation and DNA Ploldy in Malignant Breast Tumors in Relation to Early Oral Contraceptive Use and Early Abortions, Cancer, 67:1285-1290.
  5. Olsson H, Borg A, Ferno M, Ranstam J, Sigurdsson H, (1991), Her -2/neu and INT2 Proto-oncogene Amplification in Malignant Breast Tumors in Relation to Reproductive Factors and Exposure to Exogenous Hormones, J Nat Cancer Inst., 84:1483-1487.
  6. Ownby HE, Martino S, Roi LD, Howard L, Russo J, Brooks S, Brennan MJ, (1983), Interrupted Pregnancy as an Indicator Poor Prognosis in T1, 2, No. Mo Primary Breast Cancer, Breast Cancer Res Treat, 3:339-344.
  7. Pike MC, Henderson BE, Casagrande JT, Rosario I, Gray GE, (1981), Oral Contraceptive Use and Early Abortion as Risk Factors for Breast Cancer in Young Women, Br J Cancer, 43:72-76.
  8. Howe HL, Senie RT, Bzduch H, Herzfeld P, (1989), Early Abortion and Breast Cancer Risk Among Women Under Age 40, Int J Epidemiol, 18:300-304.
  9. Remennick L, (1990), Induced Abortion as a Cancer Risk Factor: A review of Epidemiological Evidence, J Epidemiol Community Health, 44:259-264.

Interviewed and Edited by Martha E. Schieber.

K-W & Area Right to Life Association    215 Lancaster St. West    Kitchener, Ontario    N2H 4T9    Tel/Fax: (519) 746-LIFE    Email: kwrtl@golden.net

The Right to Life Association of Kitchener-Waterloo and Area