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Estrogen Hormone Therapy Ups Risk of Ovarian Cance

Guest terry jackon1

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NEW YORK (Reuters Health) - The image of hormone replacement therapy, battered by last week's revelation that the risks can outweigh the benefits in the long term, received another blow from researchers on Tuesday.




They report that women who take estrogen-only hormone replacement therapy (HRT) for a long period of time have a higher-than-average risk of developing ovarian cancer.


However, Dr. James V. Lacey, Jr. and his colleagues at the National Cancer Institute in Rockville, Maryland found that women who take short rounds of estrogen that is combined with progestin seem to have no higher risk of ovarian cancer than women who have never taken HRT.


Typically, only women who have had their uterus removed take estrogen alone because the hormone is known to increase the risk of cancer of the uterine lining. Women who have a uterus take estrogen in combination with progestin, which cuts the cancer risk.


In an interview with Reuters Health, Lacey stressed that these results only suggest a link between ovarian cancer and estrogen replacement therapy and do not prove that ovarian cancer is a direct result of the estrogen.


Previous research into long-term use of estrogen did not connect it with an increased risk of ovarian cancer, the authors note, which demonstrates how easily the state of knowledge can change.


Given the recent report that estrogen/progestin combinations can increase the risk of heart disease and breast cancer when taken for more than 4 years, the choice of whether or not to take HRT can be quite complicated, Lacey added. That study found that estrogen/progestin decreased the risk of colon cancer and hip fractures, but the risks of other problems outweighed the benefits.


A second study due in 2005 will determine if estrogen alone increases the risk of heart disease and breast cancer.


"Because hormone therapy may influence so many conditions that affect women after menopause--cardiovascular disease, osteoporosis, breast cancer, uterine cancer, gallbladder disease, blood clots, and now potentially ovarian cancer--we should no longer think of a woman basing her decision to use hormones on the potential risk of just one condition," he said.


While millions of women choose HRT to reduce menopausal symptoms, many used it as a preventative therapy to reduce their risk of heart disease or the bone-thinning condition osteoporosis.


The findings, reported in the July 17th issue of The Journal of the American Medical Association, are based on a follow-up of 44,241 women who began taking HRT when they were an average of 57 years old. Some of the women had a hysterectomy but still had one or both of their ovaries.


During the study period, 329 women developed ovarian cancer. Women who took estrogen for longer periods of time had a higher risk of the disease, and the researchers noted a 7% increase in risk associated with every extra year of estrogen use.


Those who took estrogen for at least 10 years were twice as likely to develop ovarian cancer and those who used the drugs for 20 or more years were three times as likely to develop ovarian cancer as those who did not take the hormone, the report indicates.


An important caveat, Lacey and his team note, is that this study included women who began taking HRT in the 1970s, when the therapies contained higher doses of estrogen than what is in use today. "Whether long-term use of lower-dose estrogen replacement therapy increases the risk of ovarian cancer is not known," they write.


Women who took estrogen/progestin alone, or after using estrogen alone, appeared to be no more likely to develop ovarian cancer than women who did not take hormones, the study reports. However, the jury is still out on whether estrogen/progestin combinations can have an impact on ovarian cancer risk, the authors note.


"This recent emergence of an increased risk (of ovarian cancer) in long-term (estrogen) users should remind investigators that it is premature to conclude that estrogen/progestin replacement therapy has no association with ovarian cancer until other large studies specifically assess ovarian cancer risk among persons with short-term or long-term estrogen/progestin replacement therapy use," they write.


In an interview with Reuters Health, Dr. Kenneth L. Noller of Tufts University and the New England Medical Center in Boston, Massachusetts, who wrote an accompanying editorial, said that there is no obvious biological explanation for why estrogen might cause ovarian cancer.


"In general, this is one of those times when we have an observation without a good biological basis," he said. "There seems to be a clear-cut increase in ovarian cancer, but we really don't know why."


The finding is especially puzzling given that long-term use of oral contraceptives, which contain hormones similar to HRT, can reduce the risk of ovarian cancer, he noted.


He emphasized that the increased cancer risks reside with women who take HRT for long periods of time. As such, women who have "terrible menopausal symptoms should not be afraid to take HRT for a short period of time," he said.


However, for women with less severe symptoms, the answer is less clear. "With all of the new information about HRT, it seems to me that we must take a new approach to its use," Noller said.


SOURCE: The Journal of the American Medical Association 2002;288:334-341, 368-369.

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