Some Hormone Therapies May Increase Ovarian Cancer Risk
Swedish study finds treatments no longer used in United States may pose modest danger
TUESDAY, April 2, 2002 (HealthDayNews) -- Conventional wisdom has long held that hormone therapy protects women against ovarian cancer. Now, a new Swedish study refutes that wisdom by showing some forms of the therapy may actually increase a woman's risk of this killer disease.
Reporting in tomorrow's Journal of the National Cancer Institute, Swedish researchers say two particular types of hormone replacement therapy (HRT) -- estrogen alone and estrogen with limited use of progestins, the synthetic form of progesterone -- are at the center of the new finding: Both types of therapy may increase the risk of epithelial ovarian cancer, a form of the disease involving cells covering the outer surface of the ovaries.
American doctors, however, say there is little for women in the United States to fear, because both of these HRT formulas have not, for the most part, been prescribed in the country for more than 10 years.
In fact, the study of more than 4,000 Swedish women found those who used the traditional American form of HRT, consisting of a daily dose of a combined estrogen/progestin formula, had no increase in ovarian cancer.
This was not the case, however, for those using either estrogen alone or a "sequential" estrogen-progestin formula. Sequential therapy consists of using estrogen alone for a portion of the month, followed by the addition of progestin for one to two weeks of the monthly cycle.
Although the authors write that the greatest increase in ovarian cancer was seen in women who used these two forms of HRT for at 10 years or more, they also point out that the overall number of those affected was very small -- about two to three women out of every 1,000.
For gynecologic oncologist Dr. Giuseppe Del Priore, not only are these numbers small, they should be of little concern to American women.
"With ovary cancer, the trend seems to be that HRT has no effect or even protective effects, and that includes studies on epithelial ovarian cancer," says Del Priore, acting head of gynecologic oncology at New York University Medical Center.
For the most part, American doctors stopped prescribing sequential progestins as a form of HRT a decade or more ago, he adds. The use of estrogen-only therapy for women with a uterus went out of favor long before that, he says.
"Today, the most commonly prescribed form of HRT in America uses a continuous estrogen-progestin formula -- and this current dosing schedule seems to be protective against ovarian cancer or at least does not appear to increase the risk," Del Priore says.
For those who may still be using sequential progestin, Del Priore says there is still little to fear: "This is just one study, and you don't want to take it out of context."
The study relied on the very extensive Swedish cancer registry, a nationwide government database of patients. Using this data, researchers identified 655 women with epithelial ovarian cancer and compared them to 3,899 cancer-free women, all between the ages of 50 and 74.
Each of the women completed extensive questionnaires on their use of HRT and on other lifestyle factors that might influence cancer risks.
What the researchers found: In women who had their uterus and used estrogen alone for 10 years, there was a 43 percent increased risk of ovarian cancer compared to women who never used estrogen therapy. Those who had their uterus removed but retained their ovaries suffered no ill effects from estrogen therapy.
This backs up studies published last year in the Journal of the American Medical Association, which found that women who used estrogen therapy for more than 10 years had double the risk of ovarian cancer.
Perhaps more importantly, the Swedish group also found that women who had used estrogen combined with sequential progestin were up to 54 percent more likely to develop epithelial ovarian cancer than those women who never used this therapy.
The encouraging news: The Swedes also found women who used the kind of HRT most often prescribed to women in the United States did not experience any increased risk of ovarian cancer.
In addition, because the increased risks were so modest, the authors don't suggest women change their HRT regimens based on the new finding.
Del Priore definitely agrees.
"This study is something to take note of, but nothing to be alarmed over," he says.
In an interview about their research, the study authors said women should take into account all the benefits of HRT when deciding what to use.
But they add, "If our findings are replicated, it would be valuable to consider the epithelial ovarian cancer risk increase associated with the use of certain HRT regimens, especially given the prevalence of HRT use and the poor prognosis of epithelial ovarian cancer."
What To Do
To learn more about ovarian cancer risks, visit The National Ovarian Cancer Coalition. To learn more about epithelial ovarian cancer, and other types of ovarian cancer, visit the American Cancer Society.
For a free workbook to help you explore your HRT options, visit the Centers for Disease Control and Prevention.