THE TRIAL, known as the Women’s Health Initiative, found that combined hormone replacement therapy with estrogen and progestin raises a woman’s risk of breast cancer, stroke and heart disease.
       The study, which was supposed to last eight years, was stopped after only five, as it would be unethical to continue giving women the hormones, given those risks, the researchers said.
       The federal government also immediately sent a letter to the 16,000 participants and their doctors, advising them to stop the drugs.
       For years, doctors and patients alike have struggled with the question of whether the benefits of hormone therapy outweigh its risks.
       Given to replace the hormones that naturally decline after menopause, the drugs relieve hot flashes, mood swings and night sweats. And early research suggested the hormones also improve a woman’s overall health.
       Since then, studies have had conflicting results, with some hinting the drugs boost health, for example, and others finding they harm the heart.
       To settle the issue, doctors have been anxiously awaiting the results of this trial — the first and largest study to compare the effects of the drugs to placebo in healthy women.

‘DO NOT PANIC’
       Despite the findings, women taking the medications should not panic, experts stressed, noting that the absolute risk of harm to any individual is extremely small.
       For every 10,000 women taking combined hormone therapy each year, there will be just seven more coronary heart disease events such as heart attacks, eight excess breast cancers and eight more strokes than would have been expected had the drugs not been taken, the data indicated.
       And there are some benefits — chiefly a reduced risk of colorectal cancer and hip fractures, the study showed.
       The bottom line: “Women who are currently taking estrogen plus progestin should have a serious talk with their doctor to see if they should continue it,” said study author Dr. Jacques Rossouw of the National Heart, Lung, and Blood Institute.
       “Not only did this therapy not prevent heart disease, it actually increased the risk of heart disease, strokes and blood clots,” Rossouw told NBC News.
       Women taking the hormones for the short-term for hot flashes and other symptoms of menopause may not have a higher risk of disease, he added.
       But taking the drugs for years is no longer advisable, experts said.
       In an editorial accompanying the study, Drs. Suzanne Fletcher and Graham Colditz of Harvard Medical School said, “The whole purpose of healthy women taking long-term estrogen/progestin therapy is to preserve health and prevent disease.
       “The results of this study provide strong evidence that the opposite is happening for important aspects of women’s health, even if the absolute risk is low,” they said.
       “Given these results, we recommend that clinicians stop prescribing this combination for long-term use,” they said.

       NHLBI Director Dr. Claude Lenfant added, “The cardiovascular and cancer risks of estrogen plus progestin outweigh any benefits and a 26 percent increase in breast cancer risk is too high a price to pay, even if there were a heart benefit.
       “Menopausal women who might have been candidates for estrogen plus progestin should now focus on well-proven treatments to reduce the risk of cardiovascular disease, including measures to prevent and control high blood pressure, high blood cholesterol, and obesity,” Lenfant said.
       
NEW THERAPIES NEEDED
       Dr. Lori Mosca of Columbia University in New York, one of the earliest critics of using HRT to prevent heart disease, said women concerned about thinning bones and fractures can take osteoporosis drugs, or use diet and exercise.
       “We do need more research on other types of hormone replacement for the menopausal years,” she said.

      The new study, released early by the Journal of the American Medical Association because of its public health implications, is the second blow in as many weeks to hormone replacement therapy, or HRT.
       Doctors reported last week that the combination of estrogen and progestin does not protect women from heart disease after menopause and may increase their chances of developing blood clots and gallbladder disease.
       An estimated 38 percent of women past menopause take HRT for a range of reasons — some 70 million prescriptions written every year, according to the report.
       The new study enrolled 16,608 postmenopausal women aged 50 to 79 years; about half were given combined estrogen and progestin in one daily tablet, made by Wyeth under the brand name Prempro, and the rest, placebo.
       Compared with placebo, HRT raised the risk of strokes by 41 percent, heart attacks by 29 percent and breast cancer cases by 26 percent, the study showed.
       
STUDY STOPPED AFTER FIVE YEARS
       The study did not find that women taking HRT were more likely to die than the women who took placebos, but the trials was stopped after the women had taken the drugs for just over five years, the authors noted.
       The estrogen-progestin combination was formulated because taking estrogen alone was shown to increase the risk of uterine cancer. For women who have had hysterectomies and who need HRT, estrogen alone may be safer, according to Fletcher and Colditz.
       The study did not address the question of taking estrogen alone. Its benefits and risks are being evaluated in a second clinical trial of 11,000 women, also by the Women’s Health Initiative.
       
       Reuters contributed to this story.