TUESDAY, Oct. 3, 2006 (HealthDay News) -- The universe of possible health risks associated with hormone therapy just got bigger.
New research suggests that prolonged use of hormone therapy in postmenopausal women increases slightly the risk of developing ovarian cancer.
The risk does need confirmation in other studies and also needs to be weighed against other factors, the researchers cautioned.
"We've seen a growing body of evidence linking unopposed estrogen and estrogen-plus-progestin to an increased risk of ovarian cancer," said study author James V. Lacey Jr., an epidemiologist with the National Cancer Institute. "There are still some outstanding questions, but this adds more data that there is a slightly increased risk of ovarian cancer among women who used [this] hormone therapy for long durations."
Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, added, "It's another caution, but it's probably not going to be as applicable today as 10 years ago when women went on hormone therapy for longer durations."
Another study in the same publication, the Oct. 4 issue of the Journal of the National Cancer Institute, found that high levels of natural sex hormones, including estrogen, were associated with an increased risk of breast cancer in premenopausal women.
Concerns about hormone replacement therapy (HRT) were initially raised by the Women's Health Initiative (WHI), a landmark U.S. study involving 27,000 participants. Researchers halted the WHI study in 2002, after they found the regimen entailed more health risks -- most notably an increased risk for breast cancer and stroke -- than benefits.
There has been conflicting information, however, regarding HRT and ovarian cancer.
The authors of the first study found that, among a group of almost 100,000 women aged 50 to 71, those with a hysterectomy who used estrogen alone for a decade or more had almost double the risk of ovarian cancer than those who received no HRT.
Women who had not undergone a hysterectomy and who used estrogen plus progestin in sequence or continuously for five or more years also had a higher risk, compared with women who used no HRT.
But this finding probably won't change medical practice, Lichtenfeld said. "To me, the message remains pretty much the same," he said. "Currently, if you go on HRT, the recommendation based on the WHI is to go on for as short a period as possible."
And other studies on HRT and ovarian cancer would be helpful. "Because this is a rare cancer, it's even more important that we see whether other studies can replicate the findings," Lacey said.
The authors of the second study looked at blood samples from 18,521 premenopausal women and found that women with high levels of a naturally occurring type of estrogen called estradiol during the pre-ovulation phase of their menstrual cycle had a higher risk of developing breast cancer. Higher levels of testosterone and androstenedione in both the pre- and post-ovulation phases were also associated with an increased risk.
But again, nothing is likely to change in doctors' offices as a result of this finding.
"This is an interesting study. It does suggest that there's a relationship, but it won't change anything we recommend to women at this time," Lichtenfeld said. "If we were able to identify those with higher circulating levels, we might change recommendations in terms of surveillance, but the reality is that this is not something that's commonly measured."
Perhaps the bigger priority, Lichtenfeld added, is making sure women get mammograms in the first place. "We can't lose sight of the real message -- that women at average risk for breast cancer over the age of 40 need to get mammograms annually," he said.
A third study in the same issue of the journal found sad news for breast-cancer survivors: They have an increased risk of suicide for up to 30 years after diagnosis. The cumulative risk of suicide 30 years after a breast-cancer diagnosis was 0.2 percent, or 37 percent higher than the general population.
According to the study, women with breast cancer account for one in five of all cancer survivors in the United States, a total of about 2 million people in 2001.
For more on HRT, visit the U.S. National Library of Medicine.