NEW YORK (Reuters Health), Oct 16 - Induced abortion does not affect the risk of breast cancer, according to findings published in the October issue of the International Journal of Cancer.
"It is well established that pregnancies that end in a full-term birth ultimately confer a protective effect on breast cancer risk," Dr. Gillian K. Reeves, of the University of Oxford, UK, and colleagues write. "By contrast, the effect of incomplete pregnancies on the risk of breast cancer has been less clear."
The researchers examined the role of spontaneous and induced abortion on breast cancer risk among 267,361 women enrolled in the European Prospective Investigation into Cancer and Nutrition between 1992 and 2000. They data came from 20 centers across nine countries.
The women were followed for a mean of 6.6 years. A total of 4805 women were diagnosed with incident invasive breast cancer during follow-up.
"Overall, almost two-thirds (63%) of women reported never having had any type of abortion, while about one-third (33%) reported having had at least one type of abortion," Dr. Reeves and colleagues report. "About 20% of women reported ever having had a spontaneous abortion compared to about 16% who reported ever having had an induced abortion." Only 3.8% of women reported having had both types of abortion.
Compared to women who had never had a spontaneous abortion, the relative risk of breast cancer was not significantly increased among those who had a spontaneous abortion (RR = 1.07). Women who reported having at least two spontaneous abortions had a slightly increased risk of breast cancer (RR = 1.20). The relative risk among women who ever had an induced abortion compared to those who never had an induced abortion was 0.95.
"Overall, the findings provide further unbiased evidence of the lack of an adverse effect of induced abortion on breast cancer risk," the team concludes.
Last Updated: 2006-10-16 11:22:15 -0400 (Reuters Health)
Int J Cancer 2006;119:1741-1745.
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