FRIDAY, April 15 (HealthDay News) -- Is estrogen breast cancer's
friend or foe?
A recent study in the
Journal of the American Medical Association, which analyzed data from the massive Women's Health Initiative, suggested the latter when it found a reduced risk of breast cancer in women who had been on short-term estrogen therapy.
This seemed to contradict years of cautions that estrogen
therapy -- once widely prescribed as an antidote for the symptoms
of menopause and to prevent chronic diseases -- fuels estrogen
receptor-positive breast cancers.
In fact, this wily hormone can be both, according to an
editorial in the April 10 issue of
Cancer Prevention Research.
"Estrogen is bad at the right time, and estrogen is good at the right time," said editorial co-author V. Craig Jordan, considered the "father" of tamoxifen and other anti-estrogen treatments for breast cancer.
It's true, estrogen is necessary for cancer cells to grow and
multiply, but when the cancer cells develop in an environment where
estrogen hasn't been present for a while, they are killed off by an
unexpected flood of the hormone, he explained.
A state of estrogen deprivation can come years after menopause,
when production of estrogen naturally stops or even after a woman
has been receiving anti-estrogen therapy for breast cancer.
In such a state of deprivation, Jordan said, "cells grow that
are not independent of estrogen. They have learned to grow with
just a little tickle of estrogen. They're hanging on with a sort of
"When they start to form tumors and we put back normal-dose estrogen, the cells see this as a death signal because they're suddenly given a massive concentration of high-octane fuel. It's a complete overdose. Like a starving person, you can't just say sit down and eat all you want at McDonald's because you'll kill them," added Jordan, who is scientific director of Georgetown University's Lombardi Cancer Center.
It's important to remember that estrogen-alone therapy is given
only to women who have had a hysterectomy, as it can increase the
risk of endometrial cancer. Women who still have a uterus are
prescribed combined hormone replacement therapy (estrogen plus
progestin), which does carry increased risks of breast cancer.
It's also important to note that breast cancer cells are not
Like bacteria, these cells "are somewhat of a moving target.
They're changing and often reacting to their environment," said Dr.
Jennifer Litton, an assistant professor of cancer medicine at the
University of Texas MD Anderson Cancer Center in Houston. "It's
sort of a mini natural selection. If you expose it to one agent, it
will mutate and find a way to resist that agent."
That's why many women become resistant to certain therapies and
need alternatives that can outwit these constantly evolving
The authors of the
JAMA study concluded that women don't need to be concerned
about an increased risk of breast cancer from short-term use of
Even so, family history and other risk factors need to be
considered before starting a woman on hormone therapy.
But if you have a breast tumor, "estrogen should not be
considered for treatment at all," said Jordan. "If they're
postmenopausal, those women should either get tamoxifen or an
aromatase inhibitor. That is the best treatment that you can give.
It's absolutely rock solid."
On an experimental basis, doctors do have the authority to
prescribe estrogen to treat women with metastatic breast cancer who
have developed resistance to anti-hormone therapies, Jordan
The U.S. National Cancer Institute has more on
treatments for breast cancer.
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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