The Canadian Cancer Society is urging women to avoid combined hormone replacement therapy (HRT) using estrogen plus progestin, except in cases where severe menopausal symptoms do not respond to other treatments, because, among other things, it increases breast cancer risk.
The society is the first to take such a clear position, according to Heather Logan, director of cancer control policy for the Canadian Cancer Society.
The groups position drew immediate fire from Canadas obstetricians and gynecologists, whose professional society countered that combined HRT remains safe when properly used. And the Society of Obstetricians and Gynecologists of Canada (SOGC) also took the cancer society to task for adding to the "confusion and fear surrounding the use of HRT."
The cancer societys new position is based in large measure on the landmark Womens Health Initiative (WHI) study of estrogen/progestin therapy (see News, Aug. 7, 2002, "The End of an Era? Study Reveals Harms of Hormone Replacement Therapy," Vol. 94, No. 15, p. 1116), although "eight or nine" other studies were also taken into account, Logan said. The recommendation does not apply to women taking estrogen alone.
"The overall message coming from all the studies is that the risks do outweigh the benefits for most women," Logan said, adding that women should discuss the issue with their doctors.
If women decide to use combined HRT, the society said, they should use the lowest possible dose for the shortest possible time.
"Weve been following the issue very carefully (and) were confident that our statement is defensible," Logan said. But, she added, "Id like to convey the complexity of thisits not black and white and its very individual."
The WHIs randomized, double-blind trial of combined HRT, which involved 16,000 women, was halted in July 2002 when researchers observed that the overall risks for women in the HRT arm outweighed the benefits, and concluded it was no longer ethical to administer the treatment. Besides breast cancer, women in the combined HRT arm were at a higher risk of heart attacks, stroke, blood clots, and dementia.
When the study was stopped, investigators noted that, for an individual woman in the trial, the increased risk was "relatively small." But, said spokesman Jacques Rossouw, M.D., then acting director of the WHI, "even small individual risks over time, and on a population-wide basis, add up to tens of thousands of these serious adverse health events."
But a spokesman for the SOGC said the study has "unfortunate limitations" that make it hard to apply directly to the way combined HRT is used.
The main problem with the study, said Vyta Senikas, M.D., associate executive vice president of the SOGC, was that it involved mainly older womenabout two-thirds of the women were older than age 60, and the average age was 63. "Were not putting women aged 63 on HRT," she said.
In addition, many women are prescribed combined HRT to control severe menopausal symptoms, such as hot flashes, mood swings, night sweats, and difficulty concentrating. But women with such symptoms were excluded from the WHI, she said.
"When the WHI first came out," she said, "our advice was, see your doctor, because the message was, you can use HRT for the first couple of years [of menopause]," Senikas said. "The cancer society has come out with a statement a year and a half later, and theres nothing new ... . HRT is the most efficacious (treatment) for the total relief of symptoms."
But a WHI investigator, medical oncologist Rowan Chlebowski, M.D., Ph.D., of Harbor-UCLA Research and Education Institute in Torrance, Calif., said the cancer societys statement appears to "directly reflect the randomized trial results."
After the original decision to halt the study, he said, subsequent analyses in 2002 and 2003 have shown that women on combined HRT have no improvement in quality of life; a higher risk of developing dementia; more breast cancer diagnoses, with tumors found at higher stages; an increased frequency of abnormal mammograms, beginning after only 1 year; and an increased risk of coronary heart disease, apparent after only 1 year of treatment.
Chlebowski said that the case against long-term use of the therapy has been made, although there are still questions about the safety of combined HRT in the short term. "I think the debate is going to continue," he said. "We dont have any evidence for a short interval (of HRT therapy)."
The American Cancer Society is not planning to review the data and make a new statement of its own, a spokesman said. "We encourage women to talk to their doctors and weigh the risks and benefits," said epidemiologist Carmen Rodriguez, M.D.
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