Risk Factors For Breast Cancer:
Abortion, HRT, and the Double Standard
By Joel Brind, Ph.D.

With any given disease, the medical research community establishes what are risk factors and what are protective factors through the science known as epidemiology. During the past year, it was big news that the prolonged use of combination (i.e., estrogen plus progestin) hormone replacement therapy (HRT) was recognized as a risk factor for breast cancer for postmenopausal women.

This connection was given, as it were, "official" status. By official, I mean that the weight of the published scientific evidence convinced the National Cancer Institute (NCI) to acknowledge that HRT use increases a woman's future risk of developing breast cancer.

By contrast, in 2003 the same NCI pronounced that induced abortion is definitely not a risk factor for increased risk of breast cancer. Early last year the world renowned British medical journal The Lancet published an article authored by a prestigious group of Oxford researchers that came to the same conclusion.

Its lead author, Valerie Beral, undertook a publicity blitz to insist, "The totality of the worldwide epidemiological evidence indicates that pregnancies ended by induced abortion do not have adverse effects on women's subsequent risk of developing breast cancer." But as NRL News readers already know from a story in the May 2004 edition, that new study only intensified the debate.

Why? After all, can't we be sure that when science speaks, it speaks from the certainty of repeated observations conducted in an objective way?

Unfortunately, when we compare the science that concluded that prolonged use of hormone replacement therapy increases breast cancer risk and the science that concluded that an induced abortion doesn't, an objective look reveals a double standard. To document this disparity, it is important to examine the HRT/breast cancer work of a prominent Oxford University epidemiologist who just happens to be the same Valerie Beral.

Last year, Beral and her group helped establish HRT as a risk factor when they published, the "Million Woman Study" on HRT and breast cancer in the UK in The Lancet. In conducting the study, the Beral group sent questionnaires out to women between the ages of 50 and 65.

Not all women in that age group have gone through menopause. This is important. It has also long been established that women who go through menopause at a later age are at a higher risk of breast cancer. This is because they experience a lengthier exposure to the cancer-promoting hormone, estrogen. Among the premenopausal women in the study, this meant a heightened breast cancer risk of almost 60%.

Accordingly, in arriving at its conclusions, the Beral group eliminated all those women from the analysis who had not gone through menopause.

This meant that they properly compared only postmenopausal women who chose to take HRT with postmenopausal women who chose not to take HRT. The result?

Current users of HRT were found to be at higher risk of breast cancer than non-users by between 45% (for those who used HRT for less than a year) and 130% (for those on HRT for 10 years or more). This is science well conducted.

Now let's take the same scientific approach to the other potential risk factor in question, induced abortion. The parallel to HRT is really quite striking, since full-term pregnancy has similar effects to menopause on a woman's long-term breast cancer risk.

In particular, both full-term pregnancy and menopause lower a woman's breast cancer risk. The younger the woman is when either event occurs, the greater the protective effect - - i.e., the more her risk is lowered.

Remember how, to be sure that there was a proper comparison in the HRT study, no women were included who hadn't gone through menopause? Likewise, to determine whether an abortion heightens a woman's chances of having breast cancer, no women who had never been pregnant in the first place should be included. In other words, in researching whether abortion increases a woman's breast cancer risk, the correct comparison must be between pregnant women who chose abortion and pregnant women who chose childbirth.

Let's take an objective look at the methodology Beral et al. used in their study on abortion and breast cancer that appeared in the March 2004 edition of The Lancet. Right in the introduction of the paper, Beral et al. state, "Pregnancies that result in a birth are known to reduce a woman's long-term risk of breast cancer."

So far so good. (In fact, the establishment that full term pregnancy is a protective factor was aided by another large Beral et al. study in The Lancet in 2002.) Then we find, in looking at the key data summary table, that in combining the results of 52 worldwide studies, there was no increased breast cancer risk found for induced abortion.

But what was the comparison that produced this result? The title of the table unequivocally states: "Relative risk of breast cancer, comparing the effects of having a pregnancy that ended as an induced abortion versus effects of never having had that pregnancy."

But "never having had that pregnancy" is not an option for a pregnant woman considering abortion. This is not the same apples and apples comparison that Beral et al. used with HRT.

More telling is the fact that, even when using this artificial standard of "never having had that pregnancy," studies going back as far as 1957 show an increased risk when a woman has had an induced abortion. How do you get around that?

Beral et al. simply eliminated 15 previously published studies, on completely unscientific grounds. (For further details, see the NRL News, May 2004). But when scientific research is conducted objectively, it has clearly shown that abortion does increase the risk of breast cancer.

Women everywhere have the right to know it.

Joel Brind, Ph.D., is Professor of human biology and endocrinology, Baruch College, City University of New York. He is also President of the Breast Cancer Prevention Institute, and a frequent contributor to NRL News.