Study Dispels Abortion-Breast Cancer Link
Findings Show Abortion Doesn't Raise Breast Cancer Risk
Sorting Through the Studies on Breast Cancer and Abortion continued...
According to data from 44,000 women who participated in the studies analyzed, researchers found no increase in breast cancer risk among women who had a pregnancy that ended in miscarriage or abortion. In fact, women who had a pregnancy that ended in abortion had a slightly lower (7%) risk of breast cancer, and the number of abortions was not associated with any change in breast cancer risk.
"You could argue that if anything there is a small decreased risk, but I think the main thing is that it confirms very strongly that we can say quite confidently that there is no increased risk," says Beral.
Beral says the data collected from the 39,000 women who participated in retrospective studies were less reliable. Although the links between breast cancer and miscarriage were similar among the retrospective and prospective studies, the results on abortion and breast cancer varied widely between the two types of studies.
"If you've got something we know is correct, and something we're not sure about," says Bernal referring to the studies that look at data collection prospectively and retrospectively, "and we get a one-in-a-million chance that these results are similar, it suggests that the other ones are biased."
Researchers have been studying the relationship between abortion and breast cancer for nearly 50 years. Until the mid-1990s, studies on the issue had produced inconsistent results, and most of the studies were considered flawed because they involved a small number of women and many studies collected information only after breast cancer had been diagnosed.
In 1996, Joel Brind, PhD, a professor of biology and endocrinology at Baruch College of the City University of New York, published a study based on 23 independent studies that asked women with and without breast cancer whether they had ever had an abortion.
Brind's study suggested that having had an abortion increased a woman's risk of breast cancer.
But Brind takes issue with the Beral's study and says the studies used in the analysis are also flawed.