Study: Hormone-blocking drug reduces breast cancer risk

CHICAGO (AP) - Millions of women at higher-than-usual risk of
breast cancer have a new option for preventing the disease. Pfizer
Inc.'s Aromasin cut the risk of developing breast cancer by more
than half, without the side effects that have curbed enthusiasm for
other prevention drugs, a major study found.
It was the first test in healthy women of newer hormone-blocking
pills called aromatase inhibitors, sold as Arimidex, Femara and
Aromasin, and in generic form. They're used now to prevent
recurrences in breast cancer patients who are past menopause, and
doctors have long suspected they may help prevent initial cases,
Prevention drugs aren't advised for women at average risk of
breast cancer. Those at higher risk because of gene mutations or
other reasons already have two choices for prevention - tamoxifen
and raloxifene. But these drugs are unpopular because they carry
small risks of uterine cancer, blood clots and other problems.
"Here's a third breast cancer prevention drug that may in fact
be safer," said Dr. Allen Lichter, chief executive of the American
Society of Clinical Oncology.
The study was discussed Saturday at the society's annual meeting
in Chicago, along with another one that could change care for
thousands of women each year with breast cancer that has spread to
lymph nodes. It found that giving radiation to the armpit - not
just the breast - after surgery significantly lowered the chances
the cancer would come back.
The prevention study involved 4,560 women from the U.S., Canada,
Spain and France. They had at least one risk factor - being 60 or
older, a prior breast abnormality or pre-invasive cancer, or a high
score on a scale that takes into account family history and other
They were given daily doses of exemestane, sold as Aromasin, or
dummy pills. After about three years, there were 11 cases of
invasive breast cancer among those on the drug versus 32 among the
others. That worked out to a 65 percent reduction in risk for those
on the drug - enough of a benefit that independent monitors decided
all participants should be offered it.
Serious side effects, such as broken bones, high cholesterol and
heart problems, were similar in both groups. Slightly more women on
the drug reported hot flashes, fatigue, sweating, insomnia and
joint pain, but quality-of-life scores were similar.
Earlier studies of aromatase inhibitors found they can cause
bone loss, vaginal dryness, problems having sex, joint pain and
muscle aches, so it will take longer study to see if these occur,
Lichter said.
The study's leader, Dr. Paul Goss of Massachusetts General
Hospital, figured that 26 women would need to take exemestane for
five years to prevent a single case of breast cancer. Even though
this study did not compare the drug to tamoxifen, previous studies
suggested 96 women would need to take it for five years for each
breast cancer prevented.
"This is a new option for prevention of invasive breast cancer
for a wide pool of women," without the serious side effects of
tamoxifen or raloxifene, Goss said.
Still, it could be a tough sell. These women have only about a 2
percent to 3 percent risk, individually, of being diagnosed with
breast cancer in the next five years. A prevention pill that cuts
that chance by 65 percent means they'll have about a 1 percent
risk, said Dr. Eric Winer, breast cancer chief at Dana-Farber
Cancer Institute in Boston.
"Many women are not willing to take a daily medicine" for such
a small risk, he said.
Brand-name aromatase inhibitors cost $340 to $420 a month,
although some are available as generics. Aromasin's U.S. patent
expired in April and will expire in Europe and Japan in July.
Results of the study were published online by the New England
Journal of Medicine. The Canadian Cancer Society, Pfizer and the
Avon Foundation helped pay for the study. Goss and some other
researchers have been paid speakers for Pfizer and other cancer
drug makers.
A second study at the conference focused on treating breast
cancer that has spread to the lymph nodes. Standard treatment is
surgery followed by chemotherapy or hormone therapy and several
weeks of radiation to the breast. Women with large tumors or many
cancerous nodes also get radiation to the armpit and lower neck,
but doctors don't know if this helps women with smaller tumors or
only one to three cancerous nodes - a common situation.
Dr. Timothy Whelan of McMaster University in Hamilton, Ontario,
Canada, led a study of 1,832 such women. All received standard
treatment with radiation to the breast, and half also had radiation
in the armpit and lower neck area.
After about five years, 90 percent of those given wider
radiation were cancer-free versus 84 percent of the others, and
there was a trend toward better survival with more radiation.
Lung inflammation and lymphedema - painful arm swelling caused
by poor drainage - were more common with wider radiation, but
doctors said these side effects were worth the benefit of fewer
cancer recurrences.
The results are "potentially practice-changing" and will
encourage doctors to offer wider radiation, Whelan said.
The National Cancer Institute and Canadian Cancer Society paid
for the study.
Worldwide, about 1.3 million women are diagnosed with breast
cancer each year and nearly 500,000 women die of the disease. Last
year in the United States, there were about 207,000 new cases and
40,000 deaths from breast cancer.

(Copyright 2011 by The Associated Press. All Rights Reserved.)

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