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Reader’s Soapbox: Studies say abortion has no link to breast cancer

Guest Columnist

As a physician I feel compelled to respond to last Saturday’s Soapbox, “Abortion-breast cancer link mustn’t be ignored,” which argued that there is a link between abortion and breast cancer.

In fact, if one takes the time to carefully examine the studies and their results, one finds that the best medical evidence indicates that induced abortion has no effect on a woman’s risk of developing breast cancer later in life.

Two studies, one conducted in Denmark and one in Sweden, are widely acknowledged to be the most comprehensive and thorough analyses of abortion and breast cancer. In the study done in Denmark, women were tracked through a national cancer registry and an induced abortion registry; 281,000 women who had abortions were followed. The authors found no association between breast cancer and abortion.

In Sweden, 49,000 women were followed after an induced abortion. Again, a national cancer registry was used. Again, no increased risk of breast cancer was found in the women who had abortions.

According to the American Cancer Society, “Research studies have not found a cause-and-effect relationship between breast cancer and abortion.”

The National Cancer Institute writes, “One large population-based case-control study conducted among women in Shanghai, China, where induced abortion is common and not associated with social stigma, found no association between ever having had an induced abortion and breast cancer.”

The American judicial system recently considered the evidence and concluded there is no link between abortion and breast cancer. Earlier this year, two lawsuits were initiated by abortion opponents to require abortion providers to inform women of the link between abortion and breast cancer during their informed consent process. The case in California was dismissed before reaching trial because of the lack of data to show a link. In North Dakota, the judge ruled there is no evidence to make that link. The judge pointed out that both the National Cancer Institute and the American Cancer Society have reviewed the medical literature and found that no link exists.

Last Saturday’s Soapbox column cited several medical studies purporting to show an abortion-cancer risk, each of which had serious methodological flaws.

The most common error was in the method used to gather data on women’s abortion histories in the United States. Because of the stigma associated with abortion in this country, it has been shown that women underreport their abortions. It has also been proved that women who have breast cancer are more likely to report their abortions than women who have not been diagnosed with breast cancer. This bias in self-reported data can lead to significantly erroneous results.

In contrast, the studies in Sweden and Denmark were not based on self-reported data but on actual medical records in national registries. This was possible because the political climate and lack of social stigma about abortion in those countries allowed researchers access to high-quality, unbiased information.

Last week’s column also argued that the abortion issue is so political that abortion rights activists are hiding a supposed link between abortion and breast cancer. Both the media and medical establishment were accused of failing to investigate and report on this issue.

In fact, extensive research has been done. The data is clear; reputable studies show no association between induced abortion and breast cancer.

Deborah J. Oyer, M.D., of Seattle is medical director of Aurora Medical Services.

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