Timothy P. Collins, M.D.

“An IARC Monographs Working Group has concluded that combined estrogen-progestogen oral contraceptives and combined estrogen- progestogen menopausal therapy are carcinogenic to humans, after a thorough review of the published scientific evidence.” — IARC/WHO 1

“In a startling turnaround, breast cancer rates in the United States dropped dramatically in 2003, and experts said they believe it is because many women stopped taking hormone pills.” —Marilyn Marchione, Associated Press 2

Truths converge. The Church teaches a moral truth that contraception is an intrinsically evil act, which can never be justified.3  This includes, of course, use of the Pill— birth control pills (BCPs). In addition, there is accumulating evidence that use of BCPs is associated with, among other dangers, an increased risk of future breast cancer. As scientific truths cannot conflict with Church teaching, this finding should not come as a surprise.

Risks and Statistics

There are many uncontroverted dangers associated with BCP use, including heart attacks (especially in obese, diabetic, or hypertensive women), blood clots, and their associated life-threatening pulmonary emboli. Less lethal, but no less obnoxious side effects include depression, headaches, and nausea. There are also some cancers associated with BCP use: liver cancer—specifically, hepatocellular carcinoma— is mentioned in standard medical textbooks. Although not terribly common, neither is it rare; the National Cancer Institute (NCI) estimates that approximately fiftythree hundred U.S. women died in 2006 of hepatocellular carcinoma.4  For comparison, cervical cancer, whose risk is also increased by BCP use,5 claimed the lives of an estimated thirty-seven hundred women in the same year.

But it is breast cancer which concerns us here. Breast cancer is the second most common form of malignancy diagnosed in U.S. women, the most common being skin cancer. For 2006, the NCI estimates over 214 thousand new breast cancer diagnoses, and approximately 41 thousand deaths.6  If the amount of money poured into breast cancer screening programs is any indication, it is by far the most feared, and politically volatile, of any malignancy.

Lists of breast cancer risk factors can be found in any medical textbook. Genetics plays a role, such as carrying the BRCA gene, as does a significant family history of breast cancer. Like most cancers, the risk of breast cancer increases with age. There is a group of so-called “fibrocystic changes” that breast tissue can undergo, some of which confer significantly increased risk. Finally, there is a whole list of factors related to “excess estrogen exposure,” sometimes called “unopposed estrogen exposure.” These include early onset of menstruation, late menopause, late child-bearing (first child after age thirty), decreasing parity (the fewer babies a woman carries, the greater the risk), estrogen replacement after menopause, and obesity. To understand why excess estrogen exposure is a risk factor for future breast cancer, it is necessary to look at a bit of physiology.

Physiological Background and Pathology

The breast is a modified sweat gland, and its primary purpose is to produce milk. In adolescence, a young woman’s breasts begin to grow under the influence of estrogen (and, to a lesser extent, progesterone), and the numerous ducts and lobules begin to proliferate. These tissues, known as epithelia, are the source of the vast majority of breast cancers. The epithelia proliferate under the estrogenic effect, but it is not until the breast is exposed to the hormonal symphony of the completed first full-term pregnancy (FFTP) that it becomes fully mature, differentiated, and able to produce milk. Prior to the FFTP, the breast is more or less “held” in a proliferative state.

This is important, because highly proliferative tissues are more prone to develop malignancies. Every time a cell divides, it must reproduce a complete new copy of its genetic code. Errors creep in, and the accumulation of these errors—mutations in the cell’s genetic code—underlie the development of most cancers. That is why highly proliferative tissues, such as skin and GI tract epithelia, develop cancers more frequently than tissues like fat and muscle. Thus, “excess estrogen exposure” is a risk factor because it holds the breast epithelium in a proliferative state.

This brings us to the issue of BCPs and breast cancer. BCPs are, of course, various combinations of synthetic estrogens and progestins and, in some instances, progestins only. Thus, it would seem intuitively obvious that a woman who ingests (or has implanted or injected into her body) these exogenous excess estrogens would be putting herself at risk for future breast cancer. In fact, there have been papers published for decades supporting with data a relationship between BCP use and breast cancer, as well as a few papers claiming there is no link.

Publications and Research

Chris Kahlenborn, M.D., published the book Breast Cancer: Its Link to Abortion and the Birth Control Pill in 2000.7 Fully half of it is devoted to BCPs, breast cancer and, in particular, the conflicts in the data and why they might exist. The author looked at twenty studies performed between 1980 and 1999, and found that eighteen of them showed that a woman who took BCPs prior to her first full-term pregnancy (FFTP) increased her risk of future breast cancer by 40 to 72 percent, depending on the length of time she took the Pill. Further, these cancers appeared earlier, and were more aggressive, than in nonusers. The implantable and injectable forms of hormonal contraception were particularly onerous in their association with breast cancer, especially as these forms tend to be used primarily by adolescent girls and young women prior to their FFTP. The author’s point is to show that (1) most well-designed studies do show an increased risk of future breast cancer with hormonal contraceptive use, and (2) those studies which do not, suffer from significant methodological flaws.

The International Agency for Research on Cancer (IARC) and the World Health Organization (WHO) came to the same conclusion, as evidenced by their 2005 press release. Now, two more major papers have been published, both in 2006. The first is a review article in the January issue of the New England Journal of Medicine titled “Estrogen Carcinogenesis in Breast Cancer.”8  The authors conclude, “Studies of breast cancer have consistently found an increased risk associated with … exposure to exogenous estrogen plus progestin through hormone-replacement therapy and the use of oral contraceptives.” Further, the paper states, “The mechanisms of carcinogenesis in the breast caused by estrogen include the metabolism of estrogen to genotoxic, mutagenic metabolites and the stimulation of tissue growth.”9

The second major paper was published in the October 2006 Mayo Clinic Proceedings, and its lead author is the same physician who wrote the book cited above. Titled “Oral Contraceptive Use as a Risk Factor for Premenopausal Breast Cancer: A Meta-analysis,” the authors’ conclusion is succinct: “Use of [oral contraceptives] is associated with an increased risk of premenopausal breast cancer, especially with use before FFTP.”10

Is Anyone Listening?

One would think that data regarding a link between the most commonly prescribed drugs in the world, and one of the most feared cancers in the world, would receive some attention. It is easy to imagine the uproar that would ensue if we were discussing, say, appetite suppressants and breast cancer. There would be universal condemnation of the drug, rapid withdrawal from the market, massive media coverage, political posturing, and endless class action lawsuits. Yet, since the discussion is about birth control pills, the medical establishment spins the facts (“benefits outweigh the risks”) and the mainstream media is silent. Why? Because, simply, our culture is organized around contraception and its immoral counterpart, abortion. Justice Sandra Day O’Connor recognized this connection fifteen years ago when she said, “For two decades … people have organized intimate relationships and made choices … in reliance on the availability of abortion in the event that contraception should fail.”11   Taking away BCPs would be like taking away air.

The Catholic Church teaches a moral truth: contraception is evil. Scientific data teach a secular truth: hormonal contraception is dangerous. Truths converge, they do not contradict. Why should this be a surprise? Perhaps we will open our ears, and listen.

Timothy P. Collins, M.D. Surgical and Clinical Pathologist Naval Medical Center Portsmouth Portsmouth, Virginia

1 International Agency for Research on Cancer (IARC) and World Health Organization (WHO), “IARC Monographs Programme Finds Combined Estrogen-Progestogen Contraceptives and Menopausal Therapy Are Carcinogenic to Humans,” July 29, 2005, press release 167, www.iarc.fr/ENG/Press_Releases/pr167a.html.

2 Marilynn Marchione, “U.S. Breast Cancer Rate Falls,” Associated Press, December 14, 2006, http://www.breitbart.com/news/2006/12/14/D8M0Q1O86.html.

3 Catechism of the Catholic Church, n. 2370.

4 L.A.G. Ries et al. (eds). SEER Cancer Statistics Review, 1975–2003 (Bethesda, MD: National Cancer Institute, 2006), table I-1, http://seer.cancer.gov/csr/19752003/resultsmerged/sect01overview.pdf, based on November 2005 SEER data submission.

5 IARC/WHO, July 29, 2005, press release.

6 Ries et al., “SEER Cancer Statistics.”

7 Chris Kahlenborn, Breast Cancer: Its Link to Abortion and the Birth Control Pill (Dayton, OH: One More Soul, 2000).

8 J. D. Yager and N. E. Davidson, “Estrogen Carcinogenesis in Breast Cancer,” New England Journal of Medicine 354.3 (January 19, 2006): 270–282.

9 Ibid., emphasis added.

10C. Kahlenborn et al., “Oral Contraceptive Use as a Risk Factor for Premenopausal Breast Cancer: A Meta-analysis,” Mayo Clinic Proceedings 81.10 (October 2006): 1290–1302.

11Planned Parenthood of Southeastern PA v. Casey, 505 U.S. 833 (1992), sec. III.A.2, para. 3.

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