Abortion and the Increased Risk of Breast Cancer

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"There is a real risk involving abortion and breast cancer, and people should know about this risk so that if they decide to have an abortion they do it with full knowledge."

Leon Bradlow, Ph.D., director of the Laboratory of Biochemical Endocrinology at the Strang-Cornell Cancer Research Laboratory. Journal of the National Cancer Institute, December 15, 1993.

Critics who formerly dismissed the possibility of a causal relationship between induced abortion and breast cancer are increasingly on the defensive, largely as a consequence of the findings of a fascinating study published in the November 2, 1994 issue of the Journal of the National Cancer Institute (JNCl). The exhaustive work of Dr. Janet Daling and her colleagues at Seattle's Fred Hutchinson Cancer Research Center examined the possible linkage between abortion and breast cancer. Funded by the National Cancer Institute and directed by a woman who describes herself as "pro-choice," the study can hardly stand accused of coming at the issue with a pro-life tilt. Indeed, an accompanying editorial written by Dr. Lynn Rosenberg in the JNCI went out of its way to minimize and explain away the evidence which strongly supported the case that an induced abortion places women at a greater risk for breast cancer.

A number of factors contributed to making Dr. Daling's "Risk of Breast Cancer Among Young Women: Relationship to Induced Abortion" a cross-roads in the debate over whether abortion increases a woman's chance of contracting breast cancer. These significant factors include:

1. the size of the study (1,806 women -- 845 women who had breast cancer were compared with a "control" group of 961 women who did not);

2. its thoroughness -- women were interviewed one-on-one in their homes for two hours;

3. Daling et. al.'s conclusion that a spontaneous abortion -- a miscarriage -- does not heighten the risk, putting the emphasis back where it belongs, on induced abortion; and

4. the demonstration that the risk of developing breast cancer increased after an induced abortion, regardless of how old the mother was at the time of the abortion, how old the unborn child was, or whether the woman had given birth before.

What specifically did the Daling study show? Most media reports concentrated on the finding that, on the average, the chance of a woman having breast cancer before she turns 45 increases by 50 percent if she has had an abortion. But this heightened danger was dismissed in the accompanying JNCI editorial as "small in epidemiological terms." If breast cancer were rare or abortion infrequent, this editorial counter would carry more weight. There are, however, 182,000 new cases of breast cancer diagnosed every year and 46,000 women die annually. Add to this the roughly 1,530,000 abortions per year and this so-called "small" increased risk means a huge number of new cases of breast cancer. For example, abortion aside, a woman today has roughly a 10 percent chance of contracting breast cancer in her lifetime. But because every year so many women are having an abortion, even if the abortion decision increases the risk by one-half, or 50 percent (from 10 percent to 15 percent), in a few decades the results will be, at a minimum, an additional 40,000 cases of breast cancer every year.

But the Daling study contained even more frightening results, largely ignored by the media. If a woman had obtained her first abortion after age 30, her risk jumped by 110 percent. And if she had her first abortion before she turned 18, the likelihood of having breast cancer increased by 150 percent. Worse yet, if she has a family history (mother, sister, aunt) of breast cancer and had a first abortion after age 30, her risk went up by 270 percent. Most ominous of all were the results for women who had had an abortion before age 18 and who also had a family history of breast cancer. Twelve women in the Daling study fit that description. Every one of them had breast cancer!

Why Does an Induced Abortion Heighten the Risk of Breast Cancer?

One reason the association between an induced abortion and breast cancer is becoming harder to deny is that the linkage both makes sense intuitively to the layman and conforms to what scientists know about how breast cancer begins and about the protective influence a completed pregnancy affords to women. For instance, most researchers believe the cancer originates in immature, undifferentiated breast cells -- tissues which have not matured and specialized. Such cells proliferate dramatically in the first trimester of pregnancy, stimulated by increased concentrations of the female hormone estrogen. "These young, growing cells," as one science reporter put it, "if left to their own devices, are especially vulnerable to malignancy." But in the second half of pregnancy, the estrogen levels recede. Under the influence of such hormones as human placental lactogen, the immature tissues grow and differentiate rapidly into mature, specialized milk-producing tissue. Once specialization has occurred, cells are less likely to turn cancerous. That is why scientists have long known that a completed pregnancy confers protection against breast cancer. However, this process is short-circuited if a woman has an induced abortion. While the estrogen of early pregnancy still stimulates a proliferation of undifferentiated, cancer-vulnerable cells, the protection that comes from hormones released later in pregnancy never takes place. Thus, an induced abortion presents the woman with the worst of all possible worlds. She loses the protection she gains from carrying her baby to term -- studies show that the 10 percent risk of breast cancer drops to 7 percent -- while at the same time the abortion increases the normal risk -- from 10 percent to 15 percent.

Daling's study, however, only followed women into their forties. What about later in life? A path-breaking but vastly underreported study in the December 1993 issue of the Journal of the National Medical Association traced the breast cancer experience of about 1,000 black women (500 with breast cancer, 500 without) as they grew older. "Breast Cancer Risk Factors in African-American Women: The Howard University Tumor Registry Experience" confirmed that the risks of breast cancer increased much more for women who had aborted than for those who had not. This fine study found the same overall 50 percent increased risk factor for women under 40 who had aborted. But black women now in their 40s who had aborted experienced a 180 percent increased risk. The risk jumped to a whopping 370 percent for black women over 50 who had aborted.

We've always known that abortion is lethal to unborn babies; only of late has abortion's dangers to pregnant women become unmistakably clear as well.

Many press outlets and representatives of the Clinton administration have bent over backwards to hide the stark facts about abortion and breast cancer. However, with more studies "in the pipeline," it is only a matter of time and ongoing pro-life publicity before the truth wins out.


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Posted 9 Sep 2000.

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