Does medication abortion increase a woman's risk of breast cancer?

Medication abortion methods have not been shown to have any impact on a woman's risk of breast cancer. Further, there is no pathophysiologic reason to suspect that medication abortion methods would impact breast health.

Several studies have conclusively shown that there is no relationship between induced abortion (in general) and breast cancer risk. To date, the largest study on this question (involving the records of 1.5 million women) was conducted in Denmark. Using data from The National Registry of Induced Abortions and the Danish Cancer Registry, the researchers found that induced abortion(s) had no overall effect on the risk of breast cancer. The size of this study and the manner in which it was conducted provides substantial evidence that induced abortion does not affect a woman's risk of developing breast cancer and confirms the results of numerous smaller studies which have repeatedly shown that abortion neither causes, nor contributes to, the development of breast cancer.

In 2003, the National Cancer Institute in the United States convened a workshop of over 100 of the world’s leading experts on pregnancy and breast cancer risk. These experts reviewed existing research on the relationship between pregnancy and breast cancer risk, including studies of that specifically examined the relationship between induced and spontaneous abortion and breast cancer. The review included population-based studies, clinical studies, and animal research. Participants concluded that having an abortion or miscarriage does not increase a woman’s subsequent risk of developing breast cancer. A summary of their findings can be found here.

Melbye M, Wohlfahrt J, Olsen JH, et al. Induced abortion and the risk of breast cancer. N Engl J Med. 1997; 336(2): 81-85.
Beral V, Bull D, Doll R, et al. Breast cancer and abortion: Collaborative reanalysis of data from 53 epidemiological studies, including 83,000 women with breast cancer from 16 countries. Lancet. 2004;363(9414):1007-16.

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Last updated: September 2009