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Postmenopausal hormones linked to more aggressive and deadly breast cancers, study finds

Back in 2002, the Women’s Health Initiative (WHI) randomized trial found (to many, but not all, people’s surprise) that not only did taking postmenopausal hormone therapy (HT) have a deleterious effect on women’s cardiovascular systems (more heart at

Back in 2002, the Women’s Health Initiative (WHI) randomized trial found (to many, but not all, people’s surprise) that not only did taking postmenopausal hormone therapy (HT) have a deleterious effect on women’s cardiovascular systems (more heart attacks and strokes), it also raised their risk of developing breast cancer.

Within 12 months, sales of the hormones had plummeted 32 percent. Bad news for HT manufacturers. But what also dropped over the next few years was the incidence of breast cancer in the United States. Terrific news for women.

Then came the pushback. HT supporters have been parsing and picking away at the WHI data, trying to discredit its overall findings. Claims were made that women would be OK if they took the hormones for just four or five years. Or if they just took different kinds of hormones (including “natural” ones). New observational studies (which can’t prove cause and effect) were launched, and several suggested that the breast cancers associated with HT weren’t that bad (!!). The cancers tended to be less advanced, these studies suggested, and had more favorable prognoses (like being estrogen receptor positive).

Gosh. I guess that means that the trade-off (no hot flashes and protection against bone fractures vs. an increased risk of heart disease and a “not-so-bad” form of breast cancer) is worth it for women.

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Well, the scale against HT became even heavier today with the publication in the Journal of the American Medical Association (JAMA) of an 11-year follow-up of WHI participants who were taking estrogen-progestin hormones. Not only did HT increase the frequency of breast cancer, the study found, but the breast cancers that developed in the women taking the hormones were, on average, more advanced and deadly.

Nor did the researchers find any evidence that the cancers had more favorable prognostic features, such as being estrogen receptor positive. “If anything,” writes Dr. Peter Bach of the Memorial Sloan-Kettering Cancer Center in New York in an accompanying editorial, “the results suggest a trend in the direction of less favorable cancers.”

Here are the details: The rate of breast cancer death was higher among the HT users — 0.03 percent per year versus 0.01 percent per year in the study’s participants who were taking a placebo. In absolute numbers, that translates into 2.6 deaths per 10,000 women versus 1.3 deaths per 10,000 women in the placebo group. That’s twice the rate.

The HT users also had a higher death rate from all causes — 0.05 percent per year versus 0.03 percent per year in the placebo group. Again, in absolute numbers that meant 5.3 deaths versus 3.4 deaths per 10,000 women per year.

Furthermore, as Dr. Bach points out, “it is probable that the increase in breast cancer deaths due to hormone therapy has been underestimated in the current study and that with longer follow-up, the deleterious effect will appear larger.”

The absolute numbers may seem small — until you realize how many millions of women continue to take these hormones. And until you realize the main reason women are taking these pills: to stop hot flashes. Yes, hot flashes can be uncomfortable and even temporarily disabling in some women. But they are not a life-threatening disease.

Dr. Rowan T. Chlebowski, the lead author of the study and an oncologist at the Harbor-U.C.L.S. Medical Center in Torrance, Calif., told the New York Times that women and doctors need to rethink the idea that women can safely take hormones for four or five years for menopause symptoms like hot flashes and night sweats.

“I don’t think you can say that now,” he said. “I know some people have to take it because they can’t function, but the message now is that you really should try to stop after a year or two.”

Bach is even more emphatic on the issue:  “[O]ne of the lessons from the WHI is that physicians are ill-equipped to anticipate the effect of hormone therapy on long-term health,” he writes. “Clinicians who prescribe brief courses of hormone therapy for relief of menopausal symptoms should be aware that this approach has not been proven in rigorous clinical trials and that the downstream negative consequences for their patients are of uncertain magnitude.”