A comprehensive analysis of studies from around the world concludes
there is no link between having an abortion and breast cancer (Lancet. 2004;363:1007-1016). The findings were made by the Collaborative
Group on Hormonal Factors on Breast Cancer, which analyzed data from 53 epidemiological
studies conducted in 16 countries.
Studies in the late 1970s suggesting that spontaneous or induced abortion
might increase breast cancer risk have been criticized for potential bias.
Women in these studies were asked after their breast cancer diagnosis whether
they had previously had an abortion; experts believe breast cancer patients
are more likely to disclose a history of abortion because they are seeking
an explanation for their disease.
Stephenson J. No Abortion-Breast Cancer Link. JAMA. 2004;291(15):1826. doi:10.1001/jama.291.15.1826-c