The shaky science behind Kansas’ House Abortion Act.

In 1994, a paper in the Journal of the National Cancer Institute drew the public’s attention—and fire.  After interviewing 845 women who had a breast cancer diagnosis at age 45 or younger, as well as 961 “control” subjects, researchers led by Janet Daling of Seattle’s Fred Hutchinson Cancer Center observed a 50 percent higher risk of breast cancer among women who admitted to having had an abortion. (The association didn’t hold for women who said they’d had a miscarriage.) Anti-abortion groups like the National Right to Life trumpeted the report. In an accompanying editorial, epidemiologist Lynn Rosenberg acknowledged the relevance of “reproductive factors” in breast cancer development, but faulted the study’s reliance on personal, emotionally charged interviews.

The debate moved from women’s health to the political realm. Some on the left, such as Michael Castleman in Mother Jones, posited that pro-abortion rights interests risked credibility by ignoring data. The Economist countered this line of thinking with an article on “Abortion, breast cancer and the misuse of epidemiology.” Fear played in all too readily. Sociologist Barry Glassner recalls bus banner ads in Baltimore proclaiming, "Women who choose abortion suffer more and deadlier breast cancer."

What might have settled the question was a 1997 New England Journal of Medicine report. This gigantic analysis of more than 1.5 million Danish women didn’t involve interviews. The investigators culled data from Denmark’s Civil Registration System, Cancer Registry, and mandatory abortion records. They found no correlation, period. More than a few women, Jane Brody in the New York Times among them, expressed relief and hope that the study’s comprehensive scope and reliable data might “put to rest a longstanding concern.”

It didn’t. Controversy persisted to such a degree that in July 2002, the National Cancer Institute  responded to a nudge from congressional conservatives by changing information on its website. Pro-abortion rights lawmakers charged the agency with distorting and suppressing scientific information for ideological reasons. After some back-and-forth and a congressional investigation, the institute convened geneticists, epidemiologists, oncologists, and other experts to review all evidence. The conclusion rests on an NCI fact sheet: Elective abortions are not associated with an increased risk of breast cancer.

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The ethical principle of informed consent means this: A patient should know, and understand as best possible, the likely risks and benefits of a medical procedure before signing on. Now, at least five states sponsor misleading, partisan-promoted material on abortion and breast cancer risk.

Around the country, new choice-cramping laws are in the works. Many of the proposed informational mandates exploit the concept of informed consent to assure its opposite: promulgation of untruths about abortion. These bills appeal, falsely, to reason—with smart-sounding, progressive-seeming phrases, like “a right to know.” They feed  on women’s fear of a dreaded disease. Few pregnant women are sufficiently versed in science or statistics to refute their lawmakers’ misconceptions.

The bottom line is that most breast cancer cases go unexplained. There are infinite variables in an ordinary woman’s life. If I were to counsel a woman contemplating an abortion, that’s what I’d say. We know too little.