Karen Malec, The Abortion-Breast Cancer Link: How Politics Trumped Science and Informed Consent.

J. AM. PHYSYCIANS & SURGEONS, Summer 2003, at 41.

Thirty years ago the U.S. Supreme Court first determined that abortion was a right inherent in our Constitution. That decision, Roe v. Wade, gave women the right to obtain legal abortions in circumstances in which their lives were not endangered by their pregnancies. A reason cited for the decision was that modern aseptic technique and antibiotics made it possible for abortions to be performed safely. The Court's opinion of abortion safety might have been different if the justices had been aware of earlier epidemiological research supporting a relationship between abortion and breast cancer.

Two Japanese studies showed a positive association between induced abortion and breast cancer: a 1957 study reported a statistically significant relative risk of 2.61, and a 1968 study found a relative risk of 1.51. A landmark 1970 study by MacMahon showed that childbearing was helpful in reducing breast cancer risk. The study estimated that "women having their first child when aged under eighteen years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of thirty-five years or more." Their findings indicated that abortion might be an independent risk factor for the disease. Results "suggested increased risk associated with abortion--contrary to the reduction in risk associated with full-term births."

Soon after legalization, abortion became a common elective procedure and created a new field of medical research. Of thirty-eight epidemiological studies exploring an independent link with breast cancer, twenty-nine reported risk elevations, seventeen of which are statistically significant. Most medical organizations were silent about this research. In 1973, the incidence of the disease was 82.6 per 100,000, and breast cancer was considered a disease of elderly women. By 1998, female breast cancer incidence increased more than forty percent to 118.1 per 100,000, and breast...