Taking hormones after menopause may raise the risk of deadly ovarian cancer, a new analysis shows, which adds to earlier research that found the pills contribute to higher rates of breast cancer, heart problems and stroke.
Women taking estrogen and progestin also had more bleeding that required biopsies and other tests to rule out uterine or cervical cancer.
“These biopsies are part of the burden of taking the hormones,” said Garnet Anderson, a scientist at the Fred Hutchinson Cancer Research Center in Seattle who led the work. Results were published today in the Journal of the American Medical Association.
It is estimated that 1 million women were still taking the combination hormone pills as of June, down from 3.4 million, according to Wyeth Pharmaceuticals, maker of Prempro.
The Women’s Health Initiative involves more than 162,000 women around the country, including 4,000 from the Milwaukee area who are participating under the direction of professor Jane Kotchen of the Medical College of Wisconsin.
The main part of the study was stopped early and its results published in July 2002 when researchers saw that women on hormones had higher rates of breast cancer, heart problems and stroke. Since then, researchers have continued to analyze results.
This analysis involved more than 16,600 women taking estrogen and progestin together the way most women are prescribed hormones unless they’ve had a hysterectomy. Women taking these in the form of birth control pills have lower rates of ovarian cancer, so researchers thought the same might be true after menopause.
Instead, they found more cancers in women on hormone therapy.
Twenty cases of ovarian cancer developed in the 8,506 women who took the hormones compared with 12 cases in the 8,102 women who were given dummy pills. That translated to a 58% greater risk for women on hormones, but with such few cases of ovarian cancer to evaluate, researchers cannot rule out the possibility that the difference occurred because of chance, so it’s not considered statistically significant.
“You can imagine it would be considered clinically significant” to the women and their doctors, Anderson said, especially because death rates also were different nine women on hormones died of ovarian cancer vs. three on placebos.
“Ovarian cancer is very serious but is a much less common occurrence than breast cancer,” so the risk is harder to evaluate even in as large a study as Women’s Health, said Kotchen, who was not directly involved with this analysis.
This year, about 211,300 cases of breast cancer will be diagnosed in the United States compared with 25,400 cases of ovarian cancer. Breast cancer will kill fewer than one in five women with the disease, but ovarian cancer is fatal to more than half.
“Because this is such a serious cancer, I think it is something women should be very much aware of in their decision-making” about whether to take hormones, Kotchen said.
Five times as many women taking hormones had suspicious bleeding that required evaluation through biopsies and other tests 33% vs. 6% of women taking dummy pills. They also were more likely to have abnormal Pap smears.
“They had a lot more endometrial biopsies and ultrasounds just to try to stay on top of this bleeding problem. It’s not something you can ignore,” and a factor that becomes a quality-of-life issue with respect to taking hormones, Anderson said.
In a separate study in the same journal, Jane Cauley of the University of Pittsburgh analyzed Women’s Health data and found that taking hormones cut the risk of breaking a hip by 33% and of having any type of fracture by 24%.
Many previous studies have shown that hormones prevent osteoporosis and improve bone mineral density. Cauley used a formula that weighed these benefits for various groups of women against the risk of heart disease, cancers and other problems attributed to hormone use.
The latest analysis “was our way of trying to summarize all the effects and see which way the balance tipped,” Anderson said. “We really didn’t find any where the balance was on the side of benefits.”