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Experts divided over abortion, breast cancer link
October 11, 1996
Web posted at: 9:10 p.m. EDTIn this story
WASHINGTON (CNN) -- Few questions in medicine may be more controversial than whether abortion increases a women's risk of developing breast cancer.
A new report released Friday, compiled from earlier research, reignited the debate by asserting there is a link between the two, although the findings are hotly disputed.
Having an abortion increases a woman's risk of developing breast cancer by one-third, according to a statistical analysis published in the October issue of the British Medical Association's Journal of Epidemiology and Community Health.
The results demonstrate that women considering abortions should be warned that a greater risk of breast cancer exists, said Joel Brind, one of the study's four authors who is a professor of endocrinology at Baruch College in New York City.
No consensus
But the article also said there was no consensus in the medical community regarding a link between breast cancer and abortion. Some medical authorities believe the evidence of a connection remains too weak to justify, for example, legislation mandating warnings to women considering abortions.
And other sources explicitly deny the link. "There is no evidence of a direct relationship between breast cancer and ... abortion," according to the National Cancer Institute.
"There is no evidence of a direct relationship between breast cancer and ... abortion."
-- National Cancer Institute
But that's not what the researchers from Baruch and Pennsylvania State University's Hershey Medical Center in Hershey, Pennsylvania, concluded in their new report.
"The potential of induced abortions as a breast cancer risk factor continues largely to be minimized," the article said. "While the need for further research cannot be denied ... there exists the more present need for those in clinical practice to inform their patients fully about what is already known."
In a news release, the study's authors estimated that abortions now account for about 5,000 cases of breast cancer in the United States every year, and that number could reach 25,000 by the middle of the next century. In comparison, women who suffered early miscarriages did not experience a similar risk, the authors said.
Estrogen buildup
They said the trigger for the increased risk was the buildup of estrogen during pregnancy. In women who carried pregnancies to term, hormones secreted near the end of the pregnancy modified the growth and vulnerability of breast cells and resulted in a lower cancer risk, they said.
Many spontaneous abortions -- miscarriages -- occur very early in pregnancy before estrogen levels rise sharply, they said.
"Excess exposure to estrogen is involved in most known breast cancer risk factors," Brind said.
But many in the medical community disagree with the findings. Some charge the research has an anti-abortion bias. The authors deny the charge, although one of the study's researchers writes for anti-abortion newsletters.
Critics point out that the analysis is based on a summation of findings from medical records, not looking at patients over the long haul. Other studies conclude the risk is much lower and tough to prove.
Despite the conflicting conclusions, Montana and Mississippi require that women seeking an abortion be warned about breast cancer, while Louisiana, which requires warning of reproductive health risks, mentions in its informational pamphlet the conflicting data on breast cancer.
Varied conclusions
In January, a study of 16,000 American women published in the Journal of the American Medical Association showed women who had either a miscarriage or an abortion had a 12 percent higher risk of breast cancer than women who have never terminated a pregnancy. The risk was unrelated to whether the abortion was spontaneous or induced.
The Journal said in an editorial at the time that studies on the issue conflicted, and that proposed legislation in several states to require that women be warned of potential risks of abortion was premature.
"While there might have been some studies that suggest a relationship between abortion and breast cancer, this has not been conclusive and there have been many studies that have shown no relationship," said Dr. Katherine Alley of the Columbia Hospital for Women.
The Baruch-Penn State researchers collected information from 23 studies involving 25,967 women with breast cancer and 34,977 without, then reanalyzed the old data to find out how many had had abortions.
"The potential of induced abortions as a breast cancer risk factor continues largely to be minimized"
-- The Baruch-Penn State study
The practice of combining various epidemiological studies into a single superstudy, known as meta-analysis, is often used by disease trackers to reveal an effect too subtle to show up consistently in the individual studies.
No doubt this latest study will not be the final word on the issue of abortion and breast cancer. Perhaps more research on what causes the disease could shed more light on this controversial connection.
CNN Correspondent Jeff Levine, The Associated Press and Reuters contributed to this report.
Related stories:
- Planned Parenthood to test drug-induced abortions - September 12, 1996
- FDA approves last-chance treatment for cancer patients - June, 14, 1996
Related sites:
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- Induced Abortion and Breast Cancer
- Abortion and Cancer
- Medical Journal Information on the Web
- National Cancer Institute (NCI) CancerNet Database
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