Hard Facts About Hormones
USC completes the largest study ever to examine estrogen and progestin’s role in breast cancer.
A MAJOR USC study on the cancer-causing effects of hormone replacement therapy shows that both estrogen and progestin significantly increase the risk of breast cancer in postmenopausal women.
Preventive medicine professor Ronald K. Ross of the Keck School of Medicine of USC and his colleagues at the USC/ Norris Comprehensive Cancer Center found that for every five years a woman uses estrogen, the risk of breast cancer increases 6 percent. And for every five years a woman takes both estrogen and progestin, the risk of breast cancer rises 24 percent. The latter “combined therapy” is today’s standard treatment to ease the symptoms of menopause. Among those women who used combination therapy for 10 years or more, the risk of breast cancer jumps by 50 percent.
Scientists often study hormone replace-ment therapy’s effects, but this is by far the largest study to examine the effects of estrogen and progestin as well as estrogen alone on breast cancer. The USC study, published in the Journal of the National Cancer Institute, has more data than the combined world literature on this subject.
The research team looked at 1,897 postmenopausal women in Los Angeles County who were diagnosed with breast cancer in the late 1980s and mid-1990s, and compared them to 1,637 similar women with no breast cancer. The women were identified through the Cancer Surveillance Program, which Ross directs.

THE PROS AND CONS of hormone replacement therapy have long been a subject of medical debate. Doctors prescribe estrogen to postmenopausal women to prevent osteoporosis. The hormone also markedly decreases the incidence of cardiovascular disease, the No. 1 killer in the United States (a finding first reported by this same group of USC investigators). But taking estrogen alone substantially increases a woman’s risk of endometrial cancer, the most common gynecological cancer.
In response, medical scientists in the mid-1970s introduced the combined therapy of estrogen and progestin to reduce that danger – but no one was sure how combined therapy would affect the risk of breast cancer.
Ross and his colleagues conclude that the benefits of estrogen alone outweigh its risks. For each case of breast cancer in women due to long-term estrogen use, more than six deaths from heart disease are prevented, they calculate. Estrogen’s connection to endometrial cancer is offset by the fact that recent statistics show uterine cancer is five times less prevalent than breast cancer, and far less deadly.
Similar data to balance the benefits and risks of combined therapy are unavailable.
The authors concluded that doctors should provide women with information about the possible effects of hormone replacement therapy, and explain the remaining uncertainties in weighing risks against benefits.

– Paul Dingsdale and Alicia Di Rado



RESEARCH NOTES
Forget Estrogen for Alzheimer’s

ONCE THOUGHT TO be a promising treatment for Alzheimer’s disease, estrogen is now under assault by USC neurologists. A new study, published in the journal Neurology, shows the hormone isn’t an effective treatment against the debilitating disease that destroys the memory and cognitive ability of 2 to 4 million Americans.
Assumptions about estrogen’s power to combat Alzheimer’s rest on a solid biological foundation. The hormone is known to protect the brain from damage, promote the growth of brain cells and increase their plasticity. Neurons in the brain often display estrogen receptors. And estrogen seems to reduce the production of a protein thought to be a major player in the development of Alzheimer’s. Past studies have shown that women who take estrogen reduce their risk of developing the disease.
To test the hormone’s therapeutic properties, Keck School of Medicine neurologist Victor H. Henderson designed a short-term trial using Alzheimer’s patients with mild-to-moderate dementia. He hypothesized that taking estrogen would lead to better performance on cognitive tests and even improvement in the disease’s symptoms. To his surprise, Henderson found estrogen’s physiological promise didn’t deliver. Looking at different measures of both mood and cognitive ability, the USC researcher discovered no significant differences between the subjects taking the estrogen and those receiving a placebo.
No definitive therapies currently exist to ward off or reverse the dementia.

– Lori Oliwenstein


WAIT AND C

Start squeezing those oranges. A major study by USC epidemiologist James Dwyer shows that popping large quantities of vitamin C carries an unexpected risk: it may clog your arteries. Pill-poppers who downed 500 milligrams a day had two-and-a-half times thicker inner artery wall layers than normal. If they also smoked, their arteries swelled to five times the normal thickness. Mind you, 500 milligrams is 10 times the recommended dosage. But to be safe, stick with OJ. “When you extract one component of food and give it at very high levels, you just don’t know what you are doing to the system,” Dwyer told the Associated Press.




Professor of preventive medicine Ronald K. Ross and his colleagues studied 1,897 women.

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Photograph by Michael Chibaudo / Illustration by Matthew Martin

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