I’ve been reading up on the alleged abortion-breast cancer link. (Summary: Some folks say that getting an abortion increases a woman’s risk of getting breast cancer. Some say it doesn’t. There seems to be a certain correlation between which side of this debate one argues for and which side of the general abortion-rights debate one sides with. Funny, that.)
Anyway, through Avedon , I saw Emma’s rant, which linked to a short editorial in The New York Times. The Bush administration is bullying scientific groups into falling into line with its politics, the editorial says. And I believe them, but. Thing is, the editorial itself is pretty substance-free. Here’s the core paragraph:
Researchers have long debated whether abortion increases the risk of breast cancer, possibly by altering hormones and tissue development in the breast. A fact sheet distributed by the institute last March noted that studies conducted before the mid-1990's produced inconsistent results but that subsequent studies generally found no association between abortion and breast cancer. The American Cancer Society reached the same conclusion.
All full of nice, authoritative general statements of exactly the sort that I wouldn’t for a moment trust if they were about the results of the 2000 Florida election recount, so why should I trust them about this?
Charles Murtaugh wrote about this a week or two back, citing a Danish study:
As long as we're talking about first-trimester abortions, which are the majority, there is no link to breast cancer -- but the currently-available scientific evidence does find a link for later abortions. Since they're comparatively rare, and the increased risk relatively small, the public health impact is pretty minimal. [...]
More specific, but still not enough. I went to Google. Most of what I found with a simple search was sites talking up the alleged link, but I was specifically looking for sites trying to refute it in detail. I went to the Society/Issues/Abortion/Pro-Choice/ section of the Google Directory, and did a search only in that section for the phrase “breast cancer”. The resulting handful of links led me to the Feminist Women’s Health Center’s Abortion Information page, and thence to “Abortion and Breast Cancer: The Unproven Link”. Here are some details about that Danish study:
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.
OK, but reading further:
According to findings published in the January 2000 issue of Epidemiology, women who have had an induced abortion are at no more risk for breast cancer than their counterparts who did not have an abortion. Researchers at the University of Minnesota's School of Public Health-Division of Epidemiology and the Mayo Clinic examined a study sample of 1986-1995 data from 37,247 Iowa Women's Health Study participants ages 55-64, who, at the 1986 baseline, reported no history of breast cancer. Through 1995, 653 women underwent an induced abortion. [...]
Waitaminnit. In the Danish study there were 280,965 women who had abortions, 2.3% of them were in the second trimester (or third?), that’s, um, 6,462 women, and that was too few to draw a firm conclusion. So why are we even talking about studies with only a few hundred subjects? Granted, they think that 2.3% might be selected for other problems, but still.
Oh, and the American Cancer Society has a page on this matter. I’m a bit troubled by the opening paragraphs:
Research studies have not found a cause-and-effect relationship between breast cancer and abortion. There are different types of abortion:
- Induced abortion is probably what most people consider "abortion," in that a woman chooses to end a pregnancy.
- Spontaneous abortion, which most people refer to as a miscarriage, also causes the interruption of hormones. It is this interruption which is believed to increase ones' risk of developing breast cancer.
- Stillborn births, in which the fetus dies after five months gestation while still in the uterus, may cause hormonal fluctuations in the mother that are abnormal when compared to a normal, full-term pregnancy.
All of these situations have been studied to see what effect they may have on the woman's risk of developing breast cancer later in life. No link has been found between breast cancer and miscarriage or stillbirths. The research is not quite so clear with induced abortions and breast cancer.
Check out that bulleted list. Why is the information about hormone interruption and the alleged risk of cancer bundled in with the second point, when it’s actually logically associated with all three? Especially since the paragraph that follows the list implies that it might be most strongly associated with the first? That sort of writing is a warning sign.
A 1997 article in First Things, a conservative Christian magazine, raises some interesting questions about the Danish study. Not that I’m inclined to trust that source — First Things is where Philip Johnson started the “intelligent design” movement, a blatant example of scientific and intellectual dishonesty. And this article, “Abortion, Breast Cancer, and Ideology”, has its own problems, like taking a study from 1957 as seriously as one from 1997. Still, the author, Joel Brind, at least goes into enough detail that I can see the problems. So few writers do.
I’m supposed to have a conclusion here, right? Where I sum up one side as the virtuous truth-speakers and the other as lying scum-weasels. Not this time. I just don’t know which side is right here. (I do know that the Bush administration is wrong, but that’s an easy one.) I’m currently leaning towards Murtaugh’s interpretation — that there’s some increase in the cancer risk from second and third trimester abortions — and open to the possibility that there might be some with the first, just because the pro-link side tends to publish on the web in more detail. Let that be a lesson to you.