Taking menopause hormones for five years doubles the risk for breast cancer, according to a new analysis study that reveals the most dramatic evidence yet of the dangers of these still-popular pills.
Even women who took oestrogen and progestin pills for only a couple of years had a greater chance of getting cancer. And when they stopped taking them, their odds quickly improved, returning to a normal risk level roughly two years after quitting.
Collectively, these new findings are likely to end any doubt that the risks outweigh the benefits for most women.
Already a decrease in breast cancer rates
It is clear that breast cancer rates plunged in recent years mainly because millions of women quit hormone therapy and fewer newly menopausal women started on it, said the study's leader, Dr Rowan Chlebowski of Harbor-UCLA Medical Centre in Los Angeles.
"It's an excellent message for women: You can still diminish risk (by quitting), even if you've been on hormones for a long time," said Dr Claudine Isaacs of Georgetown University's Lombardi Comprehensive Cancer Centre. "It's not like smoking where you have to wait 10 or 15 years for the risk to come down."
Study results clear
The findings are from the Women's Health Initiative, which tested oestrogen and progestin pills that doctors long believed would prevent heart disease, bone loss and many other problems in women after menopause. The main part of the study was stopped in 2002 when researchers saw surprisingly higher risks of heart problems and breast cancer in hormone users.
Since then, experts have debated whether these risks apply to women who start on hormones when they enter menopause, usually in their 50s, and take them for shorter periods of time. Most of the women in the federal study were in their 60s and well past menopause.
So the advice has been to use hormones only if symptoms like hot flashes are severe, and at the lowest dose and shortest time possible.
Most women will not get breast cancer by taking the pills short-term. The increased cancer risk from a couple of years of hormone use translates to a few extra cases of breast cancer a year for every 1 000 women on hormones. This risk accumulates with each year of use, though.
HRT-related breast cancer less dangerous
In yet another study exploring the link between HRT and breast cancer researchers found that women who develop breast cancer after taking hormone therapy have a lower risk of dying from the disease.
"Hormone therapy seems to give you a particular type of cancer that is easier to treat," explained study author Sarah F. Marshall, a senior statistician at the University of California Irvine, US.
"We found that women who took hormone therapy before their diagnosis were more likely to be diagnosed with oestrogen receptor-positive cancer, as well as having breast cancers that were more favorable in other ways, [such as being] smaller and detected at an earlier stage," Marshall said.
Oestrogen-receptor positive breast cancers depend on oestrogen to grow. Giving anti-oestrogen therapy (such as tamoxifen) treats the cancer.
Results somewhat reassuring
In the study, women taking oestrogen-progestin had a 47% reduced risk of death from breast cancer during the follow-up compared to those who did not take hormone therapy. Those on oestrogen alone had an 18% reduced risk of breast cancer death, but that was not statistically significant, she said.
The study results may be somewhat reassuring for women who took hormone replacement therapy, she said. - (Sapa, Kathleen Doheny/HealthDay News)
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