Breast Cancer and Abortion: Other Questions

Chris Kahlenborn
(chapter seven)
Breast Cancer:Its link to Abortion and
the Birth Control Pill
Reproduced with Permission

Q-7A: What is the link between abortion and breast cancer if the abortion takes place after a woman's first full-term pregnancy (FFTP)?

Janet Daling noted a trend of increased risk of 50% [RR=1.5 (1.0-2.2)] in her 1994 study. Melbye et al1 found a 44% increased risk (ie, risk calculated from their raw data) for abortion in general, but did not specify how many of these abortions were after a woman's FFTP. Nevertheless, most of the abortions presented in his paper are abortions after a woman's FFTP. The most conservative and accurate figure comes from Dr. Brind et al's 1996 metaanalysis, which found that women who had an abortion after their FFTP experienced a 30% increased risk for developing breast cancer [RR=1.3 (1.1-1.5)].

Q-7B: What is the risk of abortion in women who remain nulliparous (ie, women who have not given birth to a child)?

Daling et al2 found a 70% increased risk of developing breast cancer in nulliparous women who had an induced abortion. Brind et al3 calculated a 30% overall increased risk in their meta-analysis. One must keep in mind that the 30% risk is the increased risk that nulliparous women who have had an induced abortion ("case group") have in comparison to other nulliparous women. Because nulliparity is itself a risk factor that confers an estimated 2-fold risk of developing breast cancer4, had the "cases" been compared to the general population, the risks would likely have been significantly higher.

Q-7C: Does a late-term abortion result in an even greater risk in breast cancer?

Some studies, but not all, have shown a greater risk of developing breast cancer with late-term abortions. Part of the problem in finding the answer to this question is that one study may be comparing women who have had a late-term abortion before their first full-term pregnancy (FFTP) to other women who have had their abortion after their FFTP, which obviously could affect the result, Melbye et al(1) noted that having an abortion after the 18th week of gestation resulted in an 89% increased risk, but they did not distinguish abortion prior to a FFTP from abortion after a FFTP. Rookus and Leeuwen et al5 actually obtained a lower risk for later-term abortion as compared to early abortion, but again failed to separate abortion prior to versus after a woman's FFTP (ie, he found a 110% increased risk in abortions of pregnancies of fewer than 8 weeks duration and a 60% increased risk in those abortions occurring after 8 weeks).

Fortunately some authors have examined the "before and after FFTP effect." Daling(2) noted that women who had aborted their first pregnancy between the 1st and 8th week of pregnancy sustained a 40% increased risk of breast cancer, whereas those who had aborted their first pregnancy between the 9th and 12th week had a 90% increased risk [(2), p.1588]. This is especially important when one notes that in the late 1970s and 1980s more than 45% of abortions occurred after the 8th week of pregnancy6. She also noted that women younger than the age of 18 had an 800% increased risk if they had their abortions between the 9th and 24th week. Although the data are limited, it would appear that a trend exists for a higher risk of developing breast cancer with late-term abortion, provided it is before a woman's FFTP.

Q-7D: Do women who have an induced abortion at a later age have an increased risk of breast cancer?

It would appear so. Daling et al(2) noted that women who underwent their first induced abortion at or after the age of 30 had a 110% increased risk of developing breast cancer [RR=2.1 (1.2-3.5)]. Rookus et al [(5), p.1762] also found this trend in women who had an induced abortion at an older age [RR= 2.0 (0.9-4.5)].

Q-7E: Can one estimate how many more women will get breast cancer because of induced abortion performed early in a woman's reproductive life?

Daling et al noted that of the "control" women who had abortions, only 28% had them after their first child was born [7, p.377]. Thus 72% of abortions were performed before a woman's first baby was born: 45% of them in women who went on to have a baby and 27% of them in women who were still nulliparous at the time of the study. One will note that about 1.6 million women had abortions each year in the 1980s but because about one third of these were repeat abortions, an estimated 1 million women were having their first abortion each year. If one uses Daling's statistics (ie, 45% of women had their abortion prior to their FFTP), and notes that an abortion performed before a woman's FFTP yields at least a 50% increased risk, it would mean that an extra 27,000 women will be getting breast cancer due to abortions prior to their FFTP, based on a national rate of breast cancer of 12% (ie, 1.0 million x 45% x 12% x 50%). This does not include the extra 9,720 nulliparous women (who had abortions prior to their FFTP) and 10,080 of parous women (who had abortions after their FFTP) who would be expected to get breast cancer from their abortions. Including these women, one can project that in the U.S. alone, 46,800 additional women would be expected to develop breast cancer each year due to abortion. Although this effect has already started, it will probably reach its peak after the year 2,000. (For the reader who wishes to see the specific details behind these calculations, see the end of this chapter).

Q-7F: The AMA (American Medical Association) noted in its 1992 JAMA8 that the risk of dying from maternal childbirth is nearly 12 times as great as the risk of dying from abortion. Is this a fair statement?

No, this is an inaccurate statement because it focuses on the short-term mortality statistics surrounding pregnancy and ignores the long-term mortality statistics. When a woman has an abortion the risks of death are far more subtle than were she to deliver her baby. It was noted that because of induced abortion more than 46,000 women are expected to get breast cancer annually in the U.S. If one-quarter of these women die from this cancer, it would mean 10,000 deaths occurring annually due to induced abortion. This is literally dozens of times more deaths than the number of women dying from natural child birth each year. In addition, the woman who carries her pregnancy to term will decrease her risk of developing ovarian cancer.

Another often unaccounted factor regarding mortality from abortion is the subsequent deaths from suicides in women who have had an abortion. "A teenage girl is 10 times more likely to attempt suicide if she has had an abortion in the last six months than is a comparable girl who has not had an abortion."9 In 1987, Reardon noted that 60% of the group of women who suffered from postabortion trauma experienced suicidal ideation; 28% of this group had attempted suicide; and 18% had tried it more than once10. Finally, in their Finnish study Gissler et al11 noted that women who had an induced abortion had more than 6 times the suicide rate than women who delivered their baby. If the AMA (American Medical Association) had accounted for these factors, they would have said that an abortion is far more dangerous than childbirth in the long run.

Q-7G: Does having an abortion at an early age lead to an increased risk of a more aggressive type of breast cancer?

It has already been noted that women who have an induced abortion at an early age, especially before a FFTP, have at least a 60% increased risk of developing breast cancer, with one major study showing a 150% increase in women who had their first induced abortion prior to the age of 18(2). But what about the level of aggressiveness of the breast cancer which these women get? That is, when a woman gets breast cancer it may spread rapidly (ie, metastasize quickly) or it may spread slowly, or perhaps be cured (ie, the less aggressive type of cancers).

Ownby et al, although they failed to distinguish between induced and spontaneous abortion (ie, miscarriage), noted that women who underwent one or more interrupted pregnancies had shorter time periods for recurrence of their disease. Women who had no abortions had a 10.5% recurrence rate; women who had one abortion had a 20.5% recurrence rate; and women who had 2 or more abortions had a 32.3% recurrence rate [12, p.341]. Meanwhile, Olsson et al noted that women who had an abortion at a young age developed cancers which grew faster (ie, had a higher mitotic rate) and had a higher percentage of aneuploid cells (ie, cells which have an abnormal number of chromosomes and thus are more likely to be tumor cells). He wrote: "These results indicate that the rate of tumor cell proliferation is higher in patients with breast cancer who have used oral contraceptives at an early age or who at a young age have had an early abortion. . ." [13, p.1288]. In general, the scientific evidence supports the finding that women who have had an abortion performed early in a woman's reproductive life develop a more aggressive type of breast cancer.

Q-7H: Do women who have multiple induced abortions have a higher risk of breast cancer?

In the U.S. in 1987, 42% of women having abortions had more than one induced abortion, with 16.5% having more than three and 5.5% having four or more abortions14. It was noted that Dr. Ownby found that women with breast cancer who had more than one abortion have a shorter time to recurrence of their disease after initial treatment (although she failed to separate induced from spontaneous abortion)(12). Dr. Brind et al noted in 1996 that "seven out of the 10 studies reporting the multiple abortion OR (ie, "odds ratio" report slightly (though not significantly) higher ORs for two or more, as opposed to one abortion" [(3), p.13]. He also noted that: "the extant data are therefore insufficient to draw any firm conclusions about any overall dose effect of induced abortion at the present time."(3). Few of the studies, however, measured the effect of consecutive induced abortions, especially before a FFTP. Howe et al did find that "ten cases and no controls had a history of repeated interrupted pregnancies with no intervening live births," which would yield an infinitely increased risk, in this small sample. The data then point to a trend for even more risk with multiple abortions, albeit no one has been able to quantify exactly how much more risk. A meta-analysis is needed.

Q-7I: Do women who had an abortion performed early in their reproductive life sustain an increased risk of developing breast cancer before the age of 35?

It has been noted that women who are less than 45 years old generally have an increased risk in developing breast cancer from having an abortion performed early in their reproductive life. What about women who are even younger? Most major studies show that women who had an abortion at a young age have a higher risk of developing breast cancer before the age of 35. Pike et al15 showed a 140% increased risk of developing breast cancer in women under the age of 32 if they had an abortion prior to their FFTP. Rosenberg et al16 showed no overall risk in women under the age of 40, but the age mismatching in that study was so markedly different (ie, a 12-year difference between the median age of the "cases" and "controls") that any result is suspect. Howe et al(4) noted a 90% increased risk in women under the age of 40 for women who had any abortion, and Daling et al(2) noted an 80% increased risk in women under the age of 35 if they had an abortion. There appears to be little doubt that abortion -- especially abortion prior to a FFTP -- increases the risk of developing breast cancer in women at the age of 35 or younger.

Q-7J: Do chemical abortions result in an increased risk of breast cancer?

A number of chemical abortion methods have been developed including RU-486 (mifepristone) and the Methotrexate/Cytotec methods. (Cytotec [misoprostol] is a drug that is routinely used to prevent ulcers, but is being used by certain people to induce chemical abortions). When RU-486 (which acts as an anti-progesterone) is given to a pregnant woman, it breaks the placental bond between a mother and her unborn child. A prostaglandin (ie, another drug category) is then given which initiates contractions of the mother's uterus, thereby expelling the baby. In the latter type of chemical abortion, methotrexate (a chemotherapy agent) is injected into a woman's muscle. Methotrexate also ruptures the placental bond and after a few days the woman is given Cytotec, another prostaglandin, which serves to start uterine contractions.

Because both combinations cause early abortions, there is every reason to anticipate that they will also cause an increased risk in breast cancer. As Dr. Brind stated: "Thus, there is no reason to suspect that new technologies, (such as mifepristone/misoprostol) that would result in generally earlier terminations, would not also be associated with increased breast cancer risk" [(3), p.493]. In addition, no one knows what kind of "hormonal blow" either RU-486 or methotrexate themselves might have on the breast of a pregnant woman (ie, the reader will note the consequences of a drug named DES, discussed in Chapter 10). If RU-486 or methotrexate have an additional deleterious effect such as DES did, women who participate in chemical abortions may be at even higher risk of developing breast cancer than women who had surgical abortions.

Q-7K: Will the new "birth control uaccine," which works by causing an early abortion, elevate the risk of breast cancer?

A birth control "vaccine" has been developed with the help of the World Health Organization and has already been used by Talwar et al upon women in India17. It is called the hCG vaccine. When a woman becomes pregnant, the young human embryo forms the early placental bond -- consisting of "syncytiotrophoblast cells." These cells secrete the pheromone hCG (Human Chorionic Gonadotropin) which serves to keep the corpus luteum intact (ie, a structure which remains in a woman's ovary after ovulation has occurred). Without hCG, the unborn child cannot survive, because the corpus luteum secretes progesterone which functions to keep the placental bond intact. The "vaccine"* attacks the hCG pheromone, which serves to cause an early abortion. It is possible that these early abortions could increase the risk of breast cancer, especially when one considers that a woman who is "immunized" with the "vaccine" would experience multiple early abortions each year. In addition, Russo and Russo have implicated hCG as one of the key pheromones in breast development. Thus, creating an "antibody" or "vaccine" to hCG would in effect be attacking the key hormone that aids in the protection of the breast from carcinogenesis18. "The vaccines are primarily targeted for women in Latin America, the Caribbean, Africa and the Pacific. Major funders of the research, including the World Bank and the World Health Organization, want to increase the effectiveness of population programs through the use of the vaccine"19

*The "vaccine" contains an "antibody-like" protein attached to a "carrier" such as the tetanus toxoid which was used in the experiments in India(17).

Q-7L: Could use of the intrauterine deuice (IUD) increase the risk of breast cancer?

The IUD does not stop ovulation20. It theoretically causes many abortions of unknown gestational (pre-birth) age. IUD use may thus increase a woman's risk of developing breast cancer because early abortions have the potential to elevate a woman's risk of breast cancer. This author is unaware of any long-term studies on the IUD's carcinogenic potential regarding breast cancer.

Q-7M: What other risks interact with an abortion performed early in a woman's reproductive life to increase the risk of breast cancer and how is the combined risk calculated?

In order to calculate the risk of two or more risk factors for a particular cancer one must multiply their independent risks. This is termed the "multiplier effect."

Let us take the example of a 21-year-old woman who had an abortion at age 17 and has been taking OCPs for at least 4 years and to date, has no live children. Daling noted that women who have an induced abortion prior to the age of 18 have a 150% increased risk of developing breast cancer, whereas Romieu et al noted that women who use OCPs for 4 or more years prior to a FFTP have a 72% increased risk [RR=1.72 (1.36-2.19)]. According to the multiplier effect, this young woman would now have a relative risk of: 2.5 x 1.72 = 4.3, which is a 330% increased risk! It is common knowledge that young women routinely use OCPs after their abortion. The trend towards an increased use was noted by Campbell et al who wrote: "Our findings on adolescents support those of several authors who stated that adolescent women were more likely to use contraceptives after abortion." [21, p.819] The implications of this are very serious.

Another example of the multiplier effect in regard to a positive family history of breast cancer is noted by a number of authors. Andrieu et al22 found that women who have a family history of breast cancer and who had two or more induced abortions have a 7-fold risk of breast cancer as compared to the rest of the population. Daling et al.(2) noted that women who had an abortion prior to the age of 18 and had a positive family history of breast cancer, had an infinitely increased risk (confidence interval: 1.8 to infinity) of obtaining breast cancer compared to women who had a family history and had not had an abortion performed early in their reproductive life. She also noted that women who were 30 years old or older at the time of their abortion and had a positive family history had a 270% increased risk compared to women who had a positive family history and no abortion.

Q-7N: Could oral contraceptives and other hormonal contraceptives such as Depo-Provera and Norplant be causing breast cancer due to their abortifacient properties?

It was already noted in the answer to question 3D that oral contraceptives cause early abortions (as do DepoProvera and Norplant). Because these early abortions result in rapidly declining hormone levels which may affect a woman's breast cells, it is possible that these contraceptives may be causing breast cancer because they cause early abortions.

Q-7O: Do women who have abortions drink more heavily, and does this lead to an increased risk of breast cancer?

A number of studies have noted that women who drink heavily are at increased risk for breast cancer. The reason for this is not known for sure, although it has been noted by some researchers that women who drink heavily experience an increased estrogen level in their blood and that this may increase a woman's risk of developing breast cancer 2324. Longnecker et al in their large study in 1995, found that women who had about one drink a day experienced a 39% increased risk, whereas women who had two drinks a day had a 69% increased risk of developing breast cancer.

This phenomenon is especially important because women who have had abortions tend to have a higher rate of alcohol consumption after their abortion. Speckhard25 found that 60% of women admitted to increased alcohol use following their abortion. In their survey published in 1986, Klassen and Wilsnack noted that: "Moderate and heavier drinkers combined, exceeded lighter drinkers on rates of... abortion (p< 0.001)." [26, p.376]. Finally, the Elliot Institute noted that: "women who abort are nearly four times more likely to start abusing drugs or alcohol" [27, p.1]. Because women who had an abortion tend to have a higher rate of alcohol use, they would theoretically also experience the "multiplier effect" and may well have a substantially higher risk of breast cancer.

Q-7P: Because many women who have an abortion performed early in their reproductive life also take oral contraceptives, how can one tell which factor is increasing the risk of breast cancer?

Because both an abortion performed early in the woman's reproductive life and OCP use are considered risk factors, a number of researchers have tested for them independently of each other. That is, when they perform their retrospective studies, they "separate out" the effects of an abortion performed early in a woman's reproductive life and/or OCP use in their statistical analysis, so that they can calculate the risk for either risk factor independently.

Q-7Q: Can you give an example of some studies that have done this?

Brinton et al28, Daling et al(2), and Rosenberg(16), in their studies regarding abortion as a risk factor, all adjusted for OCP use. In a similar way, Brinton et al's study [29, p.834], the CASH study [30, p.1507], and White's study [31, p.l507] all examined the risk of early OCP use and all adjusted for abortion.*

* Because it is abortion performed early in a woman's reproductive life and early OCP use that appear to be the greatest risk factors, it would appear that adjusting for them might be better than adjusting for abortion or OCP use in general. Future studies which adjust for early OCP use and/or early abortion (ie, before a FFTP) might define more clearly if one of these two risk factors is more dominant because there may be some "degree of overlap" (ie, confounding variables) between them.

Q-7R: Is there any other way in which one can separate the effects of an abortion performed early in a woman's reproductive life and early OCP use?

Yes. Remennick32 made two important observations about the Russian people. First, she noted a statistically significant correlation between the percent of abortions in primagravidas (ie, abortions in women who are pregnant with their first child) and the crude breast cancer rate (r=0.62, p<0.05). (The higher the r value, the higher the correlation, with 1.00 representing a perfect correlation). Second, she stated: "Another relevant peculiarity is the almost complete absence of oral contraceptives among Soviet women, making all the other relationships unconfounded by this potential risk factor." That is, because so few women had used OCPs, one can feel more confident that an abortion performed early in a woman's reproductive life really is a risk factor for breast cancer in Russian women.

Q-7S: If a woman who is pregnant develops breast cancer, will an induced abortiorn improve or worsen her prognosis?

Clarck and Chua, in their large classic study noted that: "those undergoing a therapeutic abortion had a poorer prognosis compared to a live birth. . ." [33, p.13]. In their series, none of the women who had breast cancer while pregnant and chose to have an abortion were alive after 11 years, whereas about 25% of the women who had breast cancer and chose to deliver their baby were alive after 12 years and 20% survived more than 20 years [(33), p.14]. One might ask, "Did the women who had induced abortions have more advanced disease than those who had live births, thus skewing the study results?" Dr. Clarck assured us that this is not the case: "The principal issue was whether therapeutic abortion was only carried out in those patients with more advanced disease. This was not the case."34 King et al obtained a similar result. ". . .patients who had termination of the pregnancy had a five year survival rate of 43 percent, whereas patients who underwent mastectomy and who went to term had a five year survival of 59 percent" [35, p.231]. Last, Isaacs commented that: "Contrary to common belief, pregnancy does not stimulate the growth of breast cancer. Thus, no justification exists for therapeutic abortion." He also noted that, "there is good evidence to show that patients who go on to become pregnant after treatment for breast cancer have a better survival." [36, p.50]

Q-7T: Do women who have additional children after developing breast cancer have a better prognosis?

In a large Danish study, Kroman et al37 noted that women who had children after being treated for breast cancer showed a trend toward having a lower mortality rate than women who had no children after treatment [RR: 0.55 (0.28-1.06)]. Clarck and Chua [(33), p.15] had noted that in a group of 30 women who became pregnant after being treated for breast cancer, women who had multiple pregnancies had a 96% 5-year survival rate, and women who had a single pregnancy had a 73% 5-year survival rate. [It is not known whether the stage of breast cancer was identical for both groups at the onset of the trial.]

Q-7U. Is the increasing rate of breast cancer, which is most prominent in Western countries, due to the abortion/oral contraception risk or is it simply due to an increase in mammography usage?

There are probably several reasons for the increase in breast cancer rates in most Western countries including lower parity rates, shorter breastfeeding time, and higher rates of abortion and early OCP use. Researcher White noted: "Recently, two other factors have emerged as possible risk factors for breast cancer: oral contraceptive use before first pregnancy and abortion before first term pregnancy" [38, p.242].

Some researchers have pointed to mammography as the culprit, claiming that with increased use of mammography, the rate of breast cancer might increase initially because more cancers would be detected. Mammography can only explain part of the increase in breast cancer, for the following reasons: First, in their study of women aged 25 to 44 years old, White et al found that although their model predicted that the increase in breast cancer incidence due to greater mammography should be 12%, in actuality the incidence of breast cancer grew by 29% between the early 1970s and late 1980s. Thus, mammography accounted for less than half the reason for rising breast cancer rates. White also noted that the increase in breast cancer "occurred proportionately between local and regional/distant stage at diagnosis" [39, p.1551]. Thus, although one might expect that an increase in mammography would result in a rise in the detection of early small tumors, one would not expect the incidence of larger tumors to be affected, which is precisely what White did find. In addition, Newcomb et al40 noted that mammography failed to account for 40% of the increased incidence of breast cancer in younger women (ie, aged 40-49 years old).

Q-7V: Is there any other reason why mammography alone does not explain the rising incidence of breast cancer in young women?

Yes. Most studies in young women note that few of their cancers are detected by mammography, thus limiting the effect of this variable. For example, Brinton et al(29) noted that most breast tumors in women under 45 were found by themselves or their partners (66.3%), whereas only 19.1% were found by mammography. "There was no evidence that tumors were more often detected by medical methods in oral contraceptive users compared to nonusers, with the respective percentages in users and nonusers being 7.9% and 8.7% respectively, for routine medical examination, and 18.4% and 21.2%, respectively, for routine mammography." [(29), p.833]. In a large English study, the authors noted that "less than 3% of breast lumps were found by a doctor." [United Kingdom study, 41, p.981]. As Colditz et al stated: "Because screening causes, at most, a transient rise in incidence and was not widespread at least through the early 1980s, its effect can explain little of the long-term increase in breast cancer incidence." [42, p.1481].

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