Should Docs Warn About an Abortion/Breast Cancer Link?
WebMD News Archive
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."