More Controversy Over Breast Cancer-Abortion Link

March 5 -- Legislatures in nearly a dozen states are considering requiring that doctors warn patients of a supposed link between abortion and breast cancer, but some experts say the proposed mandate has more to do with politics than scientific proof.

Evidence of a connection between abortion and breast cancer is very thin, according to major medical groups, including the World Health Organization and the American Cancer Society. That's why ABCNEWS' Dr. Nancy Snyderman believes political opposition to abortion is behind the mandatory warning being considered by 11 state legislatures.

"When you let [politics] dictate social policy, or in this case law, you are taking a huge leap," Snyderman told Good Morning America.

"You're scaring women unnecessarily," she said. "When you try to look at what causes breast cancer, it's difficult. We don't know. There seems to be many causes. When you try to link it to abortion, there are huge holes in retrospective studies like those sited [by proponents in the 11 state legislatures]."

Studies Called Too Small to Be Conclusive

Some doctors are insisting there is a link. The theory linking pregnancy termination and breast cancer is based on the hormonal disruption that occurs when a woman's pregnancy is interrupted.

Snyderman challenges this theory. "Right now we have a lot of smattering of little studies," she said, and the results are inconclusive.

Snyderman says the only solid study on the matter was done by WHO and the American Cancer Society and released in 1997. The study, published in the New England Journal of Medicine by Dr. Mads Melbye and his colleagues in Copenhagen, Denmark, concluded, "Induced abortions have no overall effect on the risk of breast cancer."

Despite the lack of medical evidence, the supposed link is still an issue "because it's politics," Snyderman said.

"This is always something that's dicey. The abortion issue is as slavery was many, many years ago. So, if we're going to talk about social policy and politics and various sides are going to disagree, we at least owe women solid science. Right now it's not there," she said.