FRIDAY, March 29 (HealthDay News) -- Women who take hormone
therapy that includes estrogen and progestin are at increased risk
of developing breast cancer and dying from it, especially if they
start taking the therapy just as menopause begins, a new analysis
Researchers followed nearly 42,000 women, all of whom were past
menopause, for an average of more than 11 years. Of those, more
than 25,000 did not use hormone therapy and more than 16,000 took
estrogen and progestin, also called combined hormone therapy. For
this analysis, the researchers did not include estrogen-only
therapy, used by women who have had a hysterectomy.
At the end of the follow-up period, more than 2,200 of the women
were found to have breast cancer. Compared to non-users, those who
took combined therapy were more likely to have breast cancer, said
Dr. Rowan Chlebowski, a medical oncologist at the Los Angeles
Biomedical Research Institute at Harbor-UCLA Medical Center.
Chlebowski led the study, which was published in the March 29 issue
Journal of the National Cancer Institute.
The link has been found in other studies, but Chlebowski also
found the risk was greatest among those who took the hormones
closest to menopause. "Women starting within months of menopause
had about a threefold greater risk than women starting 10 years
after menopause," Chlebowski said.
For the new analysis, Chlebowksi looked at results from the
Women's Health Initiative observational study. He compared the
findings with those from the Women's Health Initiative randomized
clinical trial, in which women were assigned to different
The Women's Health Initiative included four clinical trials and
an observational study. Women were all past menopause and were aged
50 to 79.
Chlebowski said he did the new analysis to resolve what he saw
as unanswered questions. In the trial, only about one-third, or
5,000, of the women were in their 50s when they started the study.
As that is the typical age for menopause to start, about two-thirds
of the women in the trial were in their 60s or beyond, so began to
take hormones several years after menopause.
Chlebowski set out to see if the link between breast cancer risk
and combined hormone therapy use was influenced by earlier use of
"We had a substantial number closer to menopause than the clinical trial of [the Women's Health Initiative]," he said.
He found, however, that not only was the risk of breast cancer
still increased, but it also increased even more if the women were
closer to menopause when they began to take the hormones.
He speculated that women who start the hormone therapy close to
menopause still have circulating levels of estrogen high enough to
make them exceed some threshold, beyond which it may become
Progestin is thought to play a role, too, he added.
Although others have thought that the breast cancers linked with
combined hormone therapy are often ones with a somewhat better
outlook -- another question Chlebowski thought needed more study --
he did not find that in his new analysis.
The new analysis reinforces the finding that combination hormone
therapy is linked with higher breast cancer risk, said Dr. Joanne
Mortimer, director of Women's Cancer Programs at the City of Hope
Comprehensive Cancer Center in Duarte, Calif.
Although previous research has found some good effects of
hormone therapy on the heart, she and Chlebowski said that has to
be weighed against the breast cancer risk found in much other
The new analysis also suggests that "the time of starting
hormone therapy really matters," Mortimer said. Although the
analysis found an association between the two, it did not prove a
Mortimer and Chlebowski agreed that women need to discuss the
pros and cons of hormone therapy during menopause with their
Women should seriously consider whether their symptoms, such as
hot flashes and night sweats, are limiting enough to warrant taking
hormones, Chlebowski said. Although some women are severely
bothered by symptoms, he said, others may be less bothered and can
avoid hormone therapy.
To learn more about hormone therapy after menopause, visit the
American Cancer Society.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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