Do Abortions Raise the Risk of Breast Cancer?

By Christine Gorman

Under ordinary circumstances, few people would know much about the contents of an upcoming issue of the Journal of the National Cancer Institute. But when a study says that having an abortion can increase a woman's risk of getting breast cancer, science cannot be guaranteed silence. Months before the report's scheduled publication this week, pro-life groups laid plans to trumpet the seven-year study's findings. In the opposition camp, pro-choice groups marshaled the statistics they needed to defuse the new findings. As the release date neared, editors at the Seattle Post-Intelligencer learned of the report, broke an embargo and rushed the results into print a week ahead of time.

Other newspapers and TV news shows quickly picked up the story, but most treated it gingerly, all too aware of its explosive potential. Many reporters emphasized the uncertainties inherent in the abortion study -- and in most other scientific research. The paper asserted that having an abortion raised a woman's risk of contracting breast cancer 50% on average. But, as an editorial in the NCI Journal points out, that is just about the smallest risk such a study can detect. (By contrast, a heavy smoker faces a 3000% jump in the odds of developing lung cancer.) Nonetheless, antiabortion groups suspected that the media's caution reflected a pro-choice bias. "Even if you want to say the study is inconclusive, I think women have a right to know," says Paige Cunningham, president of Americans United for Life. "Physicians routinely tell patients about much smaller risks than this."

Some reporters highlighted every possible flaw in the study, prompting epidemiologist Janet Daling of the Fred Hutchinson Cancer Research Center in Seattle to defend her team's work. She pointed out that the investigation followed 1,800 women over a seven-year period, making it one of the largest studies ever to examine the relationship between abortion and cancer. "I'm absolutely appalled that politics is entering into the science of this study," the researcher complains. "No one is getting any of the correct information out to the public."

But Daling, who is pro-choice, buried one of the most provocative findings in the fine print of a table. She and her colleagues reported that the risk of developing breast cancer was greater than average for women who had an abortion after the eighth week of pregnancy and were under the age of 18 at the time. But the scientists tucked away the fact that for these women, the risk of getting breast cancer before age 45 went up 800%. "We didn't say that in our report because we didn't want to alarm anyone before more research is done," Daling told Time.

The relatively high risk for teenage girls is precisely the sort of information that antiabortion groups are eager to publicize. Last summer, Daling says, a Virginia lawyer working for a right-to-life association dogged the scientist for days, trying to get more details about her work and asking that she serve as a spokesperson for his organization. "I said to him, 'I don't think you care one bit about breast cancer and women's health. You just want to help your cause,"' Daling recalls. "So I got rid of him."

Almost lost in all the arguments were the medical implications of the study. Researchers have known for years that women who become mothers before they are 30 seem to enjoy some protection against breast cancer. But no one knows how pregnancy produces that benefit. By focusing attention on the first trimester, Daling's work may have narrowed the search. In simplest terms, the number of new cells in the breast increases dramatically early in pregnancy. These young, growing cells, if left to their own devices, are especially vulnerable to malignancy. However, in the later stages of gestation, a woman's body releases hormones that help the cells mature, making them less susceptible to cancer-causing agents. An abortion would interrupt the production of these protective hormones.

Just as intriguing, Daling found that suffering a miscarriage, which doctors call a spontaneous abortion, did not increase the risk of breast cancer. "Even though a person may spontaneously abort a fetus at six or seven weeks' gestation, the fetus may have died much earlier," Daling explains. "Also, some spontaneous abortions are produced because the person doesn't have a sufficient number of hormones to sustain a pregnancy. Either way, breast-cell development doesn't really have a chance to get going, as it would in a healthy pregnancy."

Perhaps the greatest threat in the clash between science and politics is that researchers might allow potential controversy to deter them from investigating sensitive subjects. No one knows just what chain of events causes breast cancer, and it would be unfortunate if the fallout from the abortion wars stops some scientists from following up on important clues.

With reporting by Tara Weingarten/Los Angeles, with other bureaus