Breast Cancer: Its Link to Abortion and the Birth Control Pill (pp. 237)

World Ramifications of Oral Contraceptive Pill Use and Abortion Performed Early in a Woman's Reproductive Life

Chris Kahlenborn, MD
Reproduced with permission
(chapter fifteen)
Breast Cancer:Its link to Abortion and
the Birth Control Pill

Many of the researchers who studied oral contraceptive use or abortion performed early in a woman's reproductive life are from the U.S. Because this country has a high rate of both early OCP use and abortion, we are certainly one of the countries at highest risk for the development of new cases of breast cancer. What about the rest of the world? A number of the women in other countries are at increased risk for breast cancer, especially if they had, have, or will have a high rate of either early OCP use or induced abortion at a young age. It should be remembered that countries whose women take OCPs are at increased risk for cervical cancer (ie, a conservative estimate for 4 years of use is a 50% increase, see Chapter 13 of book). Finally, it must again be emphasized that women who live in Asian or African countries, or any other country with high rates of liver cancer, are at extreme risk if they take hormonal contraceptives for more than 5 years, because they have been estimated to increase the risk of liver cancer fourfold 1.

Risks for Women of Specified Countries:

Africa:

Africa will be at especially high risk for accelerating its liver cancer rate as the rate of oral contraceptive use is increased, noting that long–term OCP use increases liver cancer rates by 300%. In addition, if OCP use and⁄or use of progestins such as Depo–Provera and Norplant increase the transmission of the HIV virus, as is strongly suggested by the literature 2, it may be contributing to an even faster growth in the number of AIDS “cases.”

Australia:

Rohan et al 3 wrote in 1988 that: “Australia was one of the first countries in which oral contraceptive agents became available for use. The uptake of the use of oral contraceptive agents was extensive, and by the late 1960s they were used more commonly in Australia than elsewhere.” His study showed a 1.93 RR (0.44–4.4) in a group of 113 premenopausal women who had used OCPs for 19 months or more before their first full–term pregnancy (FFTP). A small study by Ellery et al 4 showed no risk with early OCP use but one cannot put much stock in a study that was so small (ie, it had only about 35 women under the age of 45). Australia's younger women may be at enormous risk because nearly 100% of women born after 1950 have reportedly used OCPs [5, 36S]. In addition, Australia has had selective use of DMPA (depot–medroxyprogesterone), which has been noted to cause a 190% increase (or more) in breast cancer in women who took it before the age of 25 for more than 2 years [6, 7]. As concerns induced abortion, Brind noted that Rohan's work showed a 160% increased risk for Australian women who had had an induced abortion [8, p.7]. Last, Australia has one of the highest rates of childless women, in those women born after 1950, putting its women at even higher risk for breast cancer because women who are nulliparous (ie, have no children) are at increased risk for developing breast cancer 9.

Brazil:

According to Population Reports 10, Brazil experienced one of the fastest increases in the use of OCPs in young women, from 1968 to 1980, in comparison to all the Latin and South American countries. This would put Brazilian women at especially high risk. A study of “ever” versus “never” oral contraceptive use done by Gomes et al and published in 1995 11 showed a 1.81 RR (1.15–2.85). Brazil had the third highest cumulative amount of OCP use when measured in total number of prescriptions used in a given country in a comparison of major developed and underdeveloped countries [10].

Canada:

Hislop noted that in the early 1980s in British Colombia, over 95% of women born after 1950 had taken OCPs [5, p. 36S]. Another Canadian study — the “Canadian National Breast Screening Study” — noted that over 80% of women born after 1940 had used OCPs [5, p.36S]. These are both very high prevalence rates — women who took them for prolonged periods of time or who began using them before their first child was born ought to be warned of their increased breast and cervical cancer risk especially in the late l990s and after the year 2000.

China:

It is estimated that at least 14 million abortions are performed annually on its people [12, p.250]. According to Henshaw: “Among the developing countries, China appears to have the highest legal abortion rate (62 abortions per 1000 women aged 15 to 44 years old), but this figure may be inflated” [12, p.251]. In addition, in 1993 at least 1 million of China's people were using injectable progestin contraceptives 13. As contraceptive use and chemical abortion increase in China (the use of chemical abortion such as RU–486 like drugs, is reportedly very high in China 14, one can expect a further increase in the rates of breast, cervical, and liver cancer. This is critical when one notes that cervical cancer is the 2nd most prevalent cancer in developing countries whereas liver cancer is the 7th most prevalent 15.

Two specific studies concerning OCP use were performed on East Asian women. Lee et al 16 in a small study published in 1992 found that 91 women who took OCPs prior to their FFTP had a 1.9 RR (0.4–7.7) of getting breast cancer compared to “controls.” In another small study, Wang et al 17 found that Chinese women who started using OCPs after the age of 35 sustained at least a 2.6–fold statistically significant relative risk. Data for OCP risk for women who took them before the age of 20 or before their FFTP was not presented. Wang also noted that women who breastfed more than 6 years had a 0.3–0.4 relative risk of developing breast cancer. According to both Wang and Yuan, China traditionally has had few young women who have used OCPs [5, p.36S].

As concerns the risk of induced abortion performed early in a woman's reproductive life, Yuan et al 18 noted that women who had an abortion prior to their FFTP, had a 2.4–fold increased risk of developing breast cancer than “controls.” They also noted that women who used OCPs after the age of 45 had a 4.00 (1.1.–16.59) relative risk. In addition, China has a high rate of childless women in those women born after 1950 [5, p.46S] and China's women have the latest age at first birth among all nations as per the Oxford study [5, p.48S]. The average age at first birth was over 26 years old, and because young Chinese women have far fewer children than any other country, this again puts them at high risk for increasing breast cancer rates in the future [5, p.47S]. It would appear that China has much to gain both medically and economically by dramatically expanding the use of Natural Family Planning.

Costa Rica:

Dr. Nancy Lee et al noted that, “by 1981, 11% of married women in Costa Rica ages 20–49 had used depot–medroxyprogesterone acetate (DMPA) and 58% had used oral contraceptives.” [19, p.1247]. DMPA is the active ingredient in Depo–Provera. She also found that women who had taken it in that country had a 2.6–fold risk (1.44.7) of developing breast cancer despite the fact that her study had a severe stack effect and death effect, both of which serve to underestimate the relative risks she found. Women who had more than a 10–year time span since they first used DMPA had a 4.0–fold (1.5–10.3) risk. Both the high use of OCPs and the noted risk for DMPA in Costa Rica put its women at increased risk for breast cancer.

Cuba:

Cuba had one of the highest abortion rates in the world in the early 1970s which puts its women at an increased risk for developing breast cancer [20, p.19].

Denmark:

The researcher Marianne Ewertz noted that: "In Denmark, oral contraceptives were released for general usage in 1966" [21, p.1176]. In addition, Denmark has a fairly high rate of induced abortion performed early in a woman's reproductive life–higher than England, Finland, and Norway [20, p.46]. As of the early 1980s, over 90% of Denmark's youngest women (ie, 13– and 14–year–olds) and over 65% of its 17 to 18 year olds chose abortion over delivery when becoming pregnant [12]. In addition, over 86% of women born after 1950 in Denmark have used OCPs according to Ewertz et al [5, p.36S]. Both of these factors put Denmark's women at increased risk for breast and cervical cancer.

Eastern European countries:

Almost all other “Eastern European countries” which have followed Russia's example of legalizing abortion in the 1950s, are at risk and will be at even higher risk should their women begin to use synthetic contraceptives. Hungary and Bulgaria had abortion rates that were even higher than those of the U.S. in the 1970s. Hungary was noted for having a high rate of abortion in its younger women [2O, p.39]. Czechoslovakia (ie, the former Czech Republic and Slovakia) also has a very high rate of abortion in women under the age of 24. Czechoslovakia and Hungary are also at special risk because of their high rate of abortions done in women over the age of 35 [20, p.46].

England:

Two separate large English studies have noted that between 82 to 93% of English women born after 1950 have used OCPs, putting this subset of young women at great risk [5, p.36S]. In addition, English women have one of the highest rates of OCP use in women under the age of 20, which also places them at high risk [5, p.40S].

France:

France has the distinction of having one of the highest rates of chemical abortion in the world (ie, via RU–486) as well as a high rate of OCP use in its younger women, with Le et al estimating that 86% of “controls” born since 1950 had used OCPs [5, p.36S; 216]. Ironically, France's own government, which controls the stockholder rights to RU–486, mandated the legality of this drug in spite of public opposition [14].

Germany:

The Federal Republic of Germany (previously West Germany) had the fourth highest cumulative amount of OCP use when measured in total number of prescriptions filled in a given country [10] placing its women at increased risk for breast and cervical cancer. German women have also had one of the lowest birth rates in the world, thus putting its women at even higher risk for breast cancer.

Greece:

This country had the second highest cumulative amount of OCP use when measured in total number of prescriptions used in a given country [10]. Its women should be carefully screened for breast, cervical, and liver cancer.

Iceland:

Tomasson et al from Iceland published a prospective study on the risks of OCP use in that country, which showed no overall risk. However, they took data from as early as 1965 which virtually invalidates their results because the researchers were collecting data on women with breast cancer before oral contraceptives even came to Iceland (ie, OCPs have been available in Iceland since 1967) [22, p.158]. They also failed to provide any data on risk of OCP use before a FFTP. In a better designed study, Tryggvadottir et al found that young women (ie, those born after 1953) who had more than 4 years of OCP use, sustained a 2.2 (1.0–4.7) RR of developing breast cancer. Tryggvadottir noted that early use of OCPs in Iceland has risen dramatically in women born between 1945 and 1947 only 20% used OCPs prior to the age of 20, whereas 82% of women born between 1963 and 1967 had used OCPs before the age of 20. He summarized by noting: “In this study, a significant association was detected between breast cancer and exposure to oral contraceptives at young age in women born after 1950, whereas no association was evident in the older cohorts, and the association was not detectable after mixing of the younger and the older cohort. The results support the findings in several recent studies of an association between oral contraceptive use and breast cancer in young women, and they stress the importance of doing separate analyses on groups with different possibilities of exposure at young age.” [23, p.142]. According to Tryggvadottir's analysis and that of Romieu et al 24, at least 82% of Iceland's young female population should be extremely concerned.

India:

The “birth control vaccine” is being studied by Talmar et al in India, supported by the World Health Organization26. Because this “vaccine” works by causing early abortion(s) and attacking one of the most important hormones that protects against breast cancer (ie, hCG), should its use become widespread, millions of Indian women could be at risk for a higher incidence of breast cancer. Cervical cancer and breast cancer are two of the most prevalent types of cancer in India [15].

Israel:

Data from the WHO trial has estimated that about 50% of Israeli women born since 1950 have used OCPs. This is a lower rate than most European countries, but its women are still at increased risk for breast cancer, especially because Jewish people in general have a higher baseline rate of breast cancer than most of the rest of the world. It was noted earlier that Jewish women have a higher frequency of a defect in the BRCA1 gene. This has special implications given that if two groups of women both had a mutation of the BRCA gene, and if one group used OCPs for 4 years or more before their first birth, that group would have a 680% increased risk of getting breast cancer 25.

Italy:

A number of studies have been done in Italy, usually under the guidance of La Vecchia. Unfortunately, many of these studies suffer from a number of weaknesses, especially low statistical power in analyzing younger aged women. In 1986, La Vecchia et al 27 published a study, funded in part by Wyeth pharmaceutical laboratories, which showed a 1.13 (0.81–1.52) multivariate relative risk of breast cancer for “ever⁄never” use of OCPs. In addition to the obvious conflict of interest as regards the drug company which helped sponsor the study, La Vecchia only provided data for women who were age 60 and under, thereby failing to analyze the one group that would have had a reasonable latent period and the possibility of using OCPs at an early age — that is, women under the age of 45 on or before 1995. He did note an increased risk after 10 years since first use in these elderly women: 1.45 (1.01–2.08).

A later study published in 1995 28 suffered from a large stack effect (ie, 4.2% of “cases” vs. 7.1% of “controls” under the age of 35). It noted a 1.3 RR (0.9–1.9) in women who took OCPs prior to their FFTP. The authors did provide a table [28, p.166] that showed that risk for OCP use increased in the younger aged groups (ie, women under the age of 45). For example, women aged 35 to 44 years old who took OCPs for fewer than 10 years had a 1.9 RR (1.22.9). Italy's young women reportedly have a lower rate of OCP use than countries such as France, former West Germany, and the U.S. [5, p.36S].

Japan:

Japan has traditionally had a lower breast cancer rate than the rest of the world, but it has been increasing dramatically in the last few years (see Chapter 1 of book). This may increase if Japanese women begin to use oral contraceptives as women in Western countries do.

Middle Eastern countries:

Little data has been published on countries in the Middle East, especially those with a Muslim majority such as Iran, Egypt, Syria, Morroco, and Iraq. If the women of these countries refrain from abortion and hormonal contraceptive use as has been reported, they would be one of the few populations in the world which would be spared from the increased risks of breast, cervical, and liver cancer.

Netherlands:

Rookus noted that women under the age of 36 who used OCPs prior to the age of 20 had a 1.44 RR per year of use (p=0.04) 29. He also noted that as of 1994, when the paper was written, 14%, 3%, and ‹ 1% of those women who were 36 years old or less, 36 to 40, 41 to 45, respectively, had used OCPs for 2 or more years prior to their FFTP. This would indicate that young women who live in the Netherlands today face a far higher increased risk of developing breast cancer than their elderly compatriots because the younger women would be more likely to have used OCPs for longer times before their FFTP. Because about 19 out of 20 women born since 1950 in the Netherlands have used OCPs, Dutch women will be at increased risk especially after the year 2000 [5, p.36S].

New Zealand:

Women in New Zealand have used DMPA (depot–medroxypro-gesterone acetate) extensively [6]. If these same women used DMPA for significant periods before their FFTP or before the age of 25, they are at increased risk according to the WHO and New Zealand trials. Skegg et al [7] pooled the results of the WHO and New Zealand studies and found that women who had taken DMPA for between 2 and 3 years before the age of 25 had a 310% statistically significant risk of getting breast cancer [RR=4.1 (1.6–10.90)] whereas women who had taken DMPA for more than 3 years prior to the age of 25 had at least a 190% increased risk that was also significant (2.9: [1.2–7.1]).

In addition, New Zealand has a high rate of early OCP use: “New Zealand women actually reported a higher prevalence of early use of the pill than the Californian population studied by Pike et al. Of our control population under 37, 30% had used oral contraceptives for 4 years or longer before the age of 25, compared with 11% in the California study” [30, p.725]. Finally, Paul et al noted that over 90% of women born since 1950 have used OCPs in New Zealand [5, p.36S].

Norway:

As of the early 1980s, over 90% of Norway's youngest women (de, 13– and 14–year–olds) chose abortion over delivery when becoming pregnant [12], putting these women at especially high risk in the future.

Russia:

Russia is a country in which abortion has been legal since 1955; it has an especially high frequency of elective abortion. “For many years after legalization in 1955, the number of abortions (roughly 7 million annually in the mid–1980s) has been exceeding the number of live births (about 5.5 million).” [31, p.506, 140]. By 1986, Henshaw estimated that Russia performed 11 million abortions annually [12, p.250]. This puts this country's women at high risk for developing breast cancer. Remennick [31] has noted that there is a statistically significant correlation between the percentage of abortions in primagravidas (ie, women who aborted 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). It should be noted that Russian women have not used oral contraceptives widely nor have they had widescale access to artificial hormones such as Norplant or Depo–Provera. Should Russian women start to use oral contraceptives or artificial progestins such as Depo–Provera in the future, they will be at even higher risk than they are currently for both breast and cervical cancer.

Singapore:

This country has one of the highest rates of early and late abortions compared to the rest of the world — putting its women at high risk for the development of breast cancer in the future [20, p.47].

South Africa:

A study performed on South African women in 1997 found that 72% of black women had used an injectable progestin contraceptive and that 30% of women had used one for 5 years or more 32. The progestin used most often was either DMPA or norethisterone and these injectable hormones have been used there since the mid 1960s. The study noted that white South African women had a far lower use of these progestin hormones. It must be noted that using DMPA for more than 2 years before the age of 25 has been noted to cause at least a 190% increased risk in breast cancer according to Skegg et al. [7]. In addition, in a large study, Herrero et al 33 found that women who had received injectable progestins (ie, usually DMPA [depot–medroxyprogesterone] or norethisterone enanthate) for at least 5 years and who had used them at least 5 years ago, suffered a 430% increased risk of developing cervical cancer [RR=5.3 (1.1–10.0)]. These two citations should alarm women from South Africa who have taken Depo–Provera because cervical cancer and breast cancer are the most common female cancers in that country respectively.

Sweden:

Meirik et al noted that: “The high prevalence of long–term (oral contraceptive) use that is found for Swedish women is in good accordance with the findings in the Swedish fertility survey in 1981, in which 30% of women aged 26 to 45 years reported that they had used OCPs for 5 years or more... To our knowledge, the proportion of long–term users in Swedish women exceeds that reported from other countries.” [34, p.653]. The same study found a 4.4 (1.2–15.5) relative risk in women who took OCPs for more than 8 years [34, p.652]. Of note, at least 87% of Swedish women born after 1950 have used OCPs according to one study [5, 36S].

In another notable Swedish study, Olsson et al 35 found a 2–fold relative risk in premenopausal women who had taken OCPs for 4 years or more prior to their FFTP. Olsson noted that 33% of the “controls” and 47% of the “cases” took OCPs before their FFTP, which is especially worrisome when one considers that he also found that women who took them before the age of 20 had a 5.8 RR (2.6–12.8), and that women who took them for more than 5 years before the age of 25 had a 5.3 RR (2.1–13.2). The author of this study warned: “The present findings, together with those of other studies on the biology of breast tumors in early users of OCPs, raise great concern about early use of OCPs.” [35, p.1004]

In addition to this, Sweden had the highest abortion rate per pregnancy of any country in the world in women under the age of 18 in the late 1970s and early 1980s [20, p.40]. This is especially dangerous because Daling et al 36 have noted that women under the age of 18 who had an induced abortion had 150% increased risk of developing breast cancer. As of the early 1980s, over 90% of Sweden's youngest women (ie, 13 and 14 year olds) and over 65% of its 17 to 18 year olds chose abortion over delivery when becoming pregnant [12].

United States:

Women in the U.S. may have the highest increased risk of developing breast cancer. They have one of the highest rates of abortion in young women, which is an especially high risk age group [20, p.39]. Of special note is that nulliparous women in the U.S. had the highest rate of abortions per 100 pregnancies. Tietze pointed out that while every country in the world had an abortion rate of less than 30 per 1,000 in women under the age of 19 in the early 1980s, the U.S. had a rate of 44.4 per 1,000! In addition, the U.S. has the “distinction” of having more than 3 times the rate of abortions compared to any other country in the world, in young women aged 13 or 14 years old [12, p.252]. States whose women might be expected to be at particularly high risk because they have high rates of abortion include: California, New York, Nevada, Massachusetts, New Jersey, Florida, and especially the District of Columbia [37, p.5].

The U.S. has the highest cumulative amount of OCP use when measured in total number of prescriptions written in a given country [10]. Even in the early 1980s, more than 84% of women born after 1950 had taken OCPs (as per the CASH study), and this Elgure has reached 90% according to a later study by Daling et al [5, p.36S]. In addition, Brinton et al, in one of the largest and most recent studies to date, noted that 72.6% of parous women had used OCPs prior to their FFTP and that 30% of parous women had taken OCPs for 4 years or more prior to their FFTP [38, p.832].

Other countries:

“Greece, Portugal, Spain, Taiwan, and Turkey all relaxed their abortion laws in the early 1980s” [12]. This implies that they will all be at increased risk in the future. It should also be noted that women who are childless and have abortions are at especially high risk. “Childless women have constituted the majority of all abortion patients in recent years in Canada, England and Wales, Finland, the Netherlands, New Zealand, Scotland, and the U.S. and they have represented the single largest subgroup in Denmark, Sweden and West Germany. In contrast, women with two previous births have represented the largest subgroup in Czechoslovakia, Hungary and Italy” [12, p.253].

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