Abortion and Breast Cancer: No Link
No Extra Breast Cancer Risk in Women Who Have Abortions
April 23, 2007 -- There is no link between abortion and breast cancer, a
10-year study shows.
Researchers base the findings on a study in which they followed 105,716
women for 10 years. They found no link between abortion and breast cancers that
occur before menopause.
Earlier large-scale studies showed no link between abortion and breast
cancers that occur after
"The globality of evidence supports no link between induced abortion and
breast cancer," Harvard researcher Karin Michels, ScD, PhD, tells
The Michels study shows a longstanding "scientific consensus," says
Michael Thun, MD, vice president for epidemiology and surveillance research at
the American Cancer Society in Atlanta. Thun was not involved in the Michels
"There is no evidence that having had an abortion increases the risk of
breast cancer," Thun tells WebMD. "This is a subject that has received
a lot of visibility; something that has been looked at repeatedly. There is
strong scientific consensus this is the case."
Abortion and Breast Cancer Risk
At one time, researchers did suspect a link between abortion and breast
cancer. Researchers who asked women about their abortion history found that
women with breast cancer were more likely than healthy women to report having
But this kind of study -- called a case/control study -- is not considered
particularly reliable. A person with a medical condition is more likely to
report an unusual or embarrassing event than is a healthy person. That's
particularly true when the event is an abortion.
"Abortion is such a personal and sensitive piece of information,"
Michel says. "If just you just ask random people, you get much more
underreporting then you do when you ask women with breast cancer, who are much
more likely to reveal all sorts of information if you ask them."
Three studies that looked at women's records about abortion before
breast cancer developed found no link to breast cancer. Three studies that
asked postmenopausal women about their abortion history and then observed them
for long periods of time also found no link to breast cancer.
In 2003, the National Cancer Institute convened an expert panel to analyze
these studies. It concluded that abortion did not affect breast cancer risk.
Michels was a member of that panel.
"No study should be interpreted on its own," Michels warns. “This
current study really supports the consensus that we came up with in 2003. So
now we can close the loop and say the lack of abortion risk seen for
postmenopausal breast cancer applies to premenopausal breast cancer as
Despite the scientific consensus, four states have laws on the books that
require doctors to warn women seeking abortion that the procedure may cause
breast cancer. Those states are Minnesota, Mississippi, Montana, and Texas. The
law in Montana has been found unconstitutional and is not enforced.
This year, there were efforts to introduce similar laws in New Hampshire,
North Dakota, and Wyoming, according to the Center for Reproductive Rights. All
of these bills failed to pass into law.
Thirty-one states have laws that require "biased counseling and/or
mandatory delays which may include providing information on breast cancer and
abortion," a spokeswoman for Physicians for Reproductive Choice and Health
The Michels study appears in the April 23 issue of Archives of Internal