Abortion and breast cancer: the unproven link.

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Scientific research does not support a link between abortion and an increased risk of breast cancer later in life, researchers at a National Cancer Institute concluded at the end of a special workshop on Feb. 26, 2003. Participants concluded that studies that claimed a connection between abortion and an increased risk of breast cancer were "flawed." Larger better-designed studies indicate no link.

Swedish Study

Since 1994, several exhaustive studies have found no tie between abortion and breast cancer. A 30-year Swedish study of 49,000 women indicated no link between abortion and breast cancer. Furthermore, the Swedish study did not suffer from an inaccurate reporting of medical histories because it was based on a national medical registry in Sweden and not based on interviews.

Largest Study Ever in Denmark, 1997

Published in 1997, a study from Denmark indicates no increased risk for women who had abortions when they analyzed medical histories of more than 1.5 million women. This larger more comprehensive study is persuasive because it does not rely upon interviews. Data came from Denmark's national health records, thereby eliminating the possibility of "recall bias." The study showed that even women who had two or more abortions were no more likely than those who never had an abortion to develop breast cancer.

The Danish study analyzed the abortion histories of 10,246 women with breast cancer among 1,529,512 women. A total of 370,715 abortions occurred in 280,965 women. Among the 2.3% of women who had abortions after the first trimester (after 12 weeks), the researchers found a gradually increasing risk of breast cancer as the stage of pregnancy advanced. However, researchers concluded that the actual number of women with second trimester abortions was too small to warrant a firm conclusion. In Denmark, abortions are both legal and free, so there are fewer reasons for women to have abortions after 18 weeks unless there are other medical problems. These other problems might themselves be the cause of the increased cancer rate.

Interestingly, women who had abortions prior to seven weeks of pregnancy actually showed a slightly decreased risk of developing breast cancer. But again, the actual number of women in this category is very small.

Also in January 1997, a Netherlands Cancer Institute study documented the existence of "recall bias" and concluded it was a significant factor affecting early studies on the link between abortion and...