* Cuts breast cancer risk 65 pct in high-risk population
* Now available as generic, cost has dropped
(Recasts first paragraph, adds physician and company
By Debra Sherman
CHICAGO, June 4 The estrogen-blocker Aromasin
was found to reduce the risk of developing breast cancer by 65
percent in post-menopausal women at high risk for breast
cancer, researchers said on Saturday.
A late-stage trial of 4,560 post-menopausal women who were
at increased risk of developing breast cancer found that those
who took the drug, also known as exemestane, had fewer invasive
breast cancers after 3 years and without severe side effects.
"We are delighted with this two-thirds reduction," Dr. Paul
Goss, director of Breast Cancer Research at Massachusetts
General Hospital, said in an interview.
He noted that there were fewer of the more aggressive types
of tumors in patients who took the drug, but the limitation of
the study was that the median follow-up was just 3 years.
The drug is sold by Pfizer Inc (PFE.N) under the brand name
Aromasin, which lost its patent April 1, 2011 and is now
available in a cheaper generic version.
The results of the study were presented in Chicago at the
annual meeting of the American Society of Clinical Oncology.
An estimated 1.3 million women are diagnosed with breast
cancer worldwide each year and nearly 500,000 die of the
disease. It is the second leading cause of cancer death among
U.S. women after lung cancer.
The study, which was sponsored by Pfizer, broke
participants up into two groups: One got the drug and the other
got a placebo. There were 11 invasive breast cancers reported
in the drug group compared with 32 in the placebo group. There
were also fewer cases of precursor lesions in the group that
Goss, who led the study, noted that tamoxifen has been used
for years to prevent breast cancer, but had serious side
effects, including raising the risk of developing uterine
cancer, cataract formations and stroke.
MILDER SIDE EFFECTS
Exemestane did not cause high levels of toxicity, he said.
Its side effects were much milder that those seen with
tamoxifen, he said, although there was a slight increase in
osteopenia -- low bone density, but not low enough to be
classified as osteoporosis.
Other side effects reported in the study included hot
flashes, sweating, fatigue, and insomnia.
"Age is the single biggest risk factor for developing
breast cancer. Once you are 60, your risk increases so this
(research) merits consideration for prevention. What we don't
know is whether patients need to take this pill for life."
After 5 years, there was no dangerous accumulation of
toxicity from the drug, he said.
"I can't look someone in the eye and swear it won't be
(toxic over a longer period of time), but there's large
evidence that the drug is safe," Goss said.
People have been taking statins to lower cholesterol and
antihypertensive medications to reduce blood pressure for
years, Goss noted. "This is the same concept."
And the price of exemestane has fallen significantly.
Commercially, even with its patent still protected,
Pfizer's Aromasin was only a moderate seller in first quarter,
with sales down 11 pct to $114 million.
The once-a-day oral tablet was originally approved to treat
advanced breast cancer in post-menopausal women who had already
been treated with tamoxifen for 2 to 3 years. The drug is also
used to treat women whose breast cancer worsened while they
were taking tamoxifen.
Exemestane belongs to a class of breast cancer drugs known
as "aromatase inhibitors," which work by decreasing the amount
of estrogen the body produces. Lower estrogen levels can slow
or even stop the growth of some breast tumors that need
estrogen to grow.
Dr. Andrew Seidman, an oncologist at New York's Memorial
Sloan-Kettering Cancer Center, called the results exciting
because exemestane gives high-risk women an alternative to
tamoxifen and to a double mastectomy just to prevent getting
Goss said he wondered whether Pfizer would try to extend
the patent based upon this new preventative indication.
A Pfizer spokesman declined to comment on the drugmaker's
"What we can say is that the ongoing evaluation of Aromasin
by the research community contributes to a growing body of
knowledge in breast cancer and may help clinicians and patients
determine the best use of aromatase inhibitor therapy," the
(Reporting by Debra Sherman, Editing by Sandra Maler)