The first follow-up of a landmark study of hormone use after menopause shows heart problems linked with the pills seem to fade after women stop taking them, while surprising new cancer risks appear.
That heart trouble associated with hormones may not be permanent is good news for millions of women who quit taking them after the government study was halted six years ago because of heart risks and breast cancer.
But the new risks for other cancers, particularly lung tumors, in women who’d taken estrogen-progestin pills for about five years puzzled the researchers and outside experts. Those risks "were completely unanticipated," said Dr. Gerardo Heiss of the University of North Carolina in Chapel Hill, lead author of the follow-up analysis.
The analysis focused on participants’ health in the first two to three years after the study’s end. During that time, those who’d taken hormones but stopped were 24 percent more likely to develop any kind of cancer than women who’d taken dummy pills during the study.
"There’s still a lot of uncertainty about the cause of the increased cancer risk," said analysis co-author Dr. JoAnn Manson, chief of preventive medicine at Harvard’s Brigham and Women’s Hospital. The cancers included breast tumors, which also occurred more frequently in hormone users during the study.
The researchers noted that the increased risks for all cancers amounted to only three extra cases per year for every 1,000 women on hormone pills, compared with nonusers. Still, Heiss said the results suggest that former hormone users need to be vigilant about getting cancer screening including mammograms.
"Vigilance is justified," he said. "No alarm, but vigilance." The initial study of 16,608 postmenopausal women was designed to examine pros and cons of taking pills long thought to benefit women’s health. It was halted in 2002 when more breast cancers, heart attacks and related problems were found in hormone users versus nonusers.
There were some health benefits – decreased risks for hip fractures and colorectal cancer – but the follow-up found those also faded after women stopped the pills. Some data suggest that U.S. breast cancer rates have declined since the study’s end.
But that likely reflects fewer women starting on the pills rather than any decline in breast cancer risk among past users, said Dr. Michael Lauer of the National Heart, Lung and Blood Institute at the National Institutes of Health, which conducted and funded the landmark research.
The authors said the new results send the same message they’ve been advocating ever since the study ended: Health risks from estrogenprogestin pills outweigh their benefits, and they should only be used to relieve hot flashes and other menopause symptoms, in the lowest possible dose for the shortest possible duration.
The new analysis appears in the Journal of the American Medical Association. A spokesman for Wyeth Pharmaceuticals, maker of the Prempro estrogen-protestin pills used in the study, voiced a criticism frequently cited by scientists, too – that participants were in their 60s on average, at least 10 years older than typical hormone users.
The latest results thus may not apply to typical users because older women have different health risks than younger ones, including more cancers in general, said Wyeth’s Dr. Joseph Camardo. Prempro’s packaging information already recommends routine breast exams and mammograms for users.
Manson, the co-author, said it’s possible the initial study results prompted hormone-using participants to see their doctors more often than nonusers after the study ended, which could have resulted in more cancers detected. It’s also possible hormones either triggered new tumors or fueled the growth of existing ones, the researchers said. "Once a tumor gets started, you might think of it as a train is out of the station and it might be more difficult to stop it," Lauer said.
The authors said the decline in heart problems was not surprising, since harmful effects of hormones on blood vessels could be expected to fade after women stopped taking the pills. Also, heart risks during the study were highest soon after women started taking hormones.
Study participant Geraldine Boggs, a Washington, D.C. nurse with three daughters and four granddaughters, said women should pay attention to the new findings. "I initially joined the study to make sure that my daughters and granddaughters had informed choices about taking them when they got to be my age," said Boggs, 64.
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