Past Study Indicates Abortion Increases Risk of Breast Cancer
Having an induced abortion may increase a woman's risk for breast cancer later in life by nearly one third, according to a review and statistical analysis of 23 studies of women with breast cancer, which appeared in the October 1996 Journal of Epidemiology and Community Health, published by the British Medical Association.
"The evidence is overwhelming," said Vernon Chinchilli, Ph.D., co-author and associate director of the Center for Biostatistics and Epidemiology at Penn State University's Milton S. Hershey Medical Center, where the studies were conducted. Eighteen of 23 studies indicated an increased risk in women who had an induced abortion, he said. The meta-analysis covers 23 separate studies with data on 25,967 women with breast cancer and 34,977 control patients without cancer.
"Our study documents a clear and significant link in worldwide published epidemiological research dating back to the first study in Japan in 1957," said principal investigator Joel Brind, Ph.D., professor of Endocrinology at Baruch College in New York City. "Yet most women are still in the dark: only three states require that women considering abortion be warned about breast cancer." The three states are Louisiana, Mississippi, and Montana.
Brind had researched connections between sex hormones and human disease for nearly 25 years. He said that pregnancies ending in early miscarriage--often called "spontaneous abortions"--do not expose women to high levels of estrogen. "Excess exposure to estrogen is involved in most known breast cancer risk factors," said Brind. "But in most pregnancies that end in miscarriage, estrogen levels never get off the ground, so breast cancer risk is not increased."
Abortion may result in an increased risk in young, childless women in two ways, said Joan Summy-Long, Ph.D., professor of Pharmacology at Hershey. "They lose the protection of a full-term pregnancy in addition to gaining the 30 per cent risk increase from the abortion," she said.
"In normal pregnancies that do go to term, hormones secreted near the end of pregnancy modify the growth and vulnerability of breast cells, resulting in lower risk for women who have children," she said. …