Thirty years ago the U.S. Supreme Court first determined that abortion was a right inherent in our Constitution. That decision, Roe et al. v. Wade, gave women the right to obtain legal abortions in circumstances in which their lives were not endangered by their pregnancies.
A reason cited for the decision was that modern aseptic technique and antibiotics made it possible for abortions to be performed safely. The court's opinion of abortion safety might have been different if the justices had been aware of earlier epidemiological research supporting a relationship between abortion and breast cancer.
Epidemiologic Evidence of an Abortion/Breast Cancer Link
Two Japanese studies showed a positive association between induced abortion and breast cancer: a 1957 study reported a statistically significant relative risk of 2.61, and a 1968 study found a relative risk of 1.51.
A landmark 1970 study by MacMahon et al. showed that childbearing was helpful in reducing breast cancer risk. The study estimated that "women having their first child when aged under 18 years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of 35 years or more." Their findings indicated that abortion might be an independent risk factor for the disease. Results "suggested increased risk associated with abortion--contrary to the reduction in risk associated with full-term births."
Soon after legalization, abortion became a common elective procedure and created a new field of medical research. Thirty-eight epidemiological studies exploring an independent link with breast cancer have been published. Twenty-nine report risk elevations. Thirteen out of 15 American studies found risk elevations. Seventeen studies are statistically significant, 16 of which report increased risk. Biological evidence provides a plausible mechanism for this statistical association.
Most medical organizations were silent about this research, but there was still enough concern about a causal relationship to lead scientists to publish another 36 studies after 1973, the year abortion was legalized. In 1973, the incidence of the disease was 82.6 per 100,000, and breast cancer was considered a disease of elderly women. By 1998, female breast cancer incidence increased more than 40 percent to 118.1 per 100,000, and breast cancer became a young woman's disease.
Researchers from the National Cancer Institute (NCI), the Centers for Disease Control and Prevention (CDC), the American Cancer Society (ACS), and the North American Association of Central Cancer Registries collaborated on a troubling report on cancer status in the years 1973 through 1998, published in 2001.
Significantly, the absolute numbers of reported excess cases agree with a prediction made in a 1996 review and meta-analysis. Its lead author, Joel Brind, Ph.D., professor of biology and endocrinology at City University of New York's Baruch College, concluded from a review of the 2001 report: "Abortion can explain the entire rise in breast cancer since the mid 1980s, and it's not just because the rise is in women young enough to have had an abortion. It's also that the absolute numbers of increased cases fall within the range of the numbers we predicted in our 1996 meta-analysis" (Brind J, personal communication, 2002).
Brind et al. estimated that in 1996 an excess of 5,000 cases of breast cancer were attributable to abortion, and that the annual excess would increase by 500 cases each year. They predicted 25,000 excess cases in the year 2036.
Among the three oldest age groups (50-64, 65-74, and 75 and older), only the 50-64 group had an increase in breast cancer rates between the years 1987 and 1998. These women belong to the generation and were just young enough for some to have had abortions.
Combining all age groups, the increase in incidence was 0.4 percent per year for whites, 0.9 percent per year for blacks, and 0.5 percent per year total. An annual percentage change of 0.5, based on 160,000 total cases in 1987, results in 800 more cases yearly. Because the estimate made by Brind et al. concerned only the independent effect of abortion, not the delayed childbirth effect, their estimate of the number of additional cases was on target.
Silence and Denial
In the influential 2001 report, the disparity in breast cancer rates between the Roe generation and the older cohort was not explained. The omission of the effect of abortion is startling: lead authors Holly Howe and Phyllis Wingo had published earlier research showing a positive association between abortion and breast cancer. Moreover, Howe was also lead author of a record-linkage case-control study in 1989, which reported a statistically significant 90 percent increased risk among post-abortive New York residents. Wingo was a CDC researcher in 1986 when she coauthored a letter to The Lancet that stated: "Induced abortion before first term pregnancy increases the risk of breast cancer," citing two American studies.
In 1997 Wingo led a group of ACS researchers who reviewed the research. By then, 11 of 12 US studies indicated increased risk. Eight studies were statistically significant, but Wingo still stated that the research was "inconsistent" and that she could not arrive at "definitive conclusions."
Professor Brind noted Wingo's inconsistent conclusions and observed: "...the overall trend of the data in the direction of increased risk is unmistakable."
Angela Lanfranchi, M.D., a clinical assistant professor of surgery at the Robert Wood Johnson Medical School, had an explanation for medical experts' silence. In a false-advertising lawsuit filed against Planned Parenthood, in which the abortion provider's statements about the research are being challenged, Lanfranchi declared under oath:
In September 1999 I wrote a letter to the president and each of the board members of my medical society, the American Society of Breast Surgeons. My letter...said that doctors...need to get this information about abortion and breast cancer to the public, and asked that an expert be invited to address the society on this issue. Some time later I called the president, Dr. Rachel Simmons, and she told me, apologetically, that she presented it to the board but they felt it was "too political."
In March 2000, I attended the Miami Breast Cancer Conference...I asked the conference director, Dan Osman M.D., if he knew there was a link between abortion and breast cancer. I was stunned when he said that he did. I asked him why there couldn't be a presentation about it at the meeting. He said it was "too political."
Over the past three or four years, I have spoken with many authorities and people in a position to be well informed. Some have been straightforward and said they know it is a risk factor but felt it was "too political" to speak about. Others have been evasive....Some have been openly hostile....Some initially hostile doctors...debated it with me and have changed their minds.
Some pro-choice doctors have come to agree it is true and do tell their patients about the risk. Some doctors who were initially skeptical have started obtaining a complete reproductive history on their patients and found, as I did, that....cases of breast cancer in young women are associated with an abortion history....
The first American study, published in 1981, found that a "first trimester abortion before FFTP first full-term pregnancy, whether spontaneous or induced, was associated with a 2.4-fold increase in breast cancer risk."
Oxford scientists hastily published a larger study, which included 1,176 cases. They said that their findings "are entirely reassuring, being in fact more compatible with protective effects than the reverse" (OR=0.84). Yet, they revealed a flaw in their study when they said, "Only a handful of women stated that they had had a termination before their first term pregnancy...."
Nineteen years later, one of these scientists and others at Oxford stated, incorrectly, that "none of the cohort or record-linkage studies have shown a significant increase in breast cancer risk after exposure to induced abortion." More than 90 percent of the study's post-abortive cases and controls were misclassified as not having had abortions, a difficulty reminiscent of a severely criticized but widely quoted 1999 Danish study by Melbye et al.
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