Dec. 5, 2001 -- Should doctors add to the distress of abortion by warning that it might -- or might not -- slightly increase the risk of future breast cancer? No, says a new review of the scientific evidence.
The review takes the form of an editorial in the journal The Lancet Oncology. Author Tim Davidson, MD, argues that telling a woman about the evidence for and against an abortion/breast cancer link makes a hard decision harder.
Why is this an issue? Anti-abortion groups have seized on studies suggesting that women have a slight but significant increase in breast-cancer risk if they have an abortion. Many of these groups overstate the risk in their efforts to persuade women to continue their pregnancies. Pro-choice groups point to studies suggesting that there is no such risk. Both sides in the highly-charged debate point to flaws in the studies they don't agree with.
"In the absence of robust evidence that an increased risk of breast cancer in later life is relevant to her deliberations, a woman deciding whether to opt for termination or to continue with an unwanted pregnancy has a hard enough task without being made to confront the breast-cancer issue," writes Davidson, a breast surgeon and lecturer in medicine at Royal Free Hospital, London.
Davidson's article lays out the theory behind the abortion/breast-cancer link. It considers arguments on both sides. It concludes that the jury is still out. That's also the conclusion of the U.S. National Cancer Institute and the American Cancer Society, says Joann Schellenbach, national director of medical and scientific information for the ACS.
"The article itself will be very useful, because our role is to collect information from scientific research to give women guidance," Schellenbach tells WebMD. "This supports the idea that it is not possible to give guidance one way or the other because the evidence from scientific studies doesn't justify it."
This is hardly the last word on the subject.
"There is no other issue than abortion that would be so immune from the concept of informed consent," Joel Brind, PHD, tells WebMD. "What could possibly be more paternalistic to a young woman making such an important decision? Davidson wants 'robust evidence' of relevance beyond any proof of a link between breast cancer and abortion. If you don't have proof a woman is going to be concerned, you shouldn't tell her. That just blew me away."
Brind, a professor of biology and endocrinology at Baruch College of the City University of New York, is lead author of the most important scientific study to link abortion to breast cancer. This 1996 study analyzed data from 23 independent studies that asked women with and without breast-cancer whether they had ever had an abortion.
The study suggested that having had an abortion increased a woman's risk of breast cancer by about 30%. That's a relatively small risk -- having a sister or mother with breast cancer increases a woman's risk by 200-300%. Having two alcoholic drinks a day increases breast cancer risk by 40-70%.
Women who never give birth -- or who have their first child after age 30 -- have a 200-300%greater risk of breast cancer than a woman who gives birth before age 20. Nobody is sure why. Since there is a link between reproductive history and breast cancer, abortion could theoretically affect risk.
Critics of Brind's study point to the fact that it relies on women to report having had an abortion. Women looking for an explanation of their breast cancer may be less reluctant than healthy women to report abortions. Studies probing this issue contradict each other.
The strongest study to show no link between breast cancer and abortion is a 1999 study led by Mads Melbye, MD, head of the epidemiology department at Denmark's Statens Serum Institut. In Denmark, women's detailed medical records are a matter of record. Analysis of these records for 1.5 million women -- including 280,965 who had abortions and 10,246 who had breast cancer -- showed absolutely no effect of abortion on breast cancer.
"We had information on women before they developed breast cancer -- and we followed the women forward," Melbye tells WebMD. "We actually found no effect, absolutely zero. For many years we had registered all women who had induced abortions. We have a file of who they are. You can then link those up against the entire population of women in Denmark. You have all women's full reproductive history. That kind of information is important because these reproductive risk factors also have an independent effect on breast cancer by themselves, so if you have many cases, your risk of making an error is reduced."
Brind is a vocal critic of Melbye's work. "There is so much wrong with that paper, it is just like how not to do a study," he says. He insists that researchers routinely cover up evidence linking breast cancer to abortion, and that the U.S. NCI and CDC promote a political, pro-abortion agenda. Brind's critics point to his presentations to anti-abortion groups as proof of his own political agenda.
Brind raises a number of valid objections. None seems to justify overturning the advice of the U.S. National Cancer Institute, the American Cancer Society, and the United Kingdom's Royal College of Obstetricians and Gynecologists. That advice: women considering abortion need not worry about the risk of breast cancer.
Click here for more information on breast-cancer risk factors