Aromasin May Cut Breast Cancer Return
Study Shows Switching to Aromasin After Tamoxifen Therapy Cuts Risk of Cancer Coming Back
WebMD News Archive
Dec. 15, 2006 (San Antonio) -- The breast cancer drug
Aromasin cuts the risk of breast cancer recurrence by
about one-third in postmenopausal women previously treated with tamoxifen,
Only 9% of women given Aromasin -- after completing tamoxifen treatment --
suffered a recurrence, compared with 11% of those given placebo, says
researcher Terry Mamounas, MD, associate professor of surgery at Northeastern
Ohio Universities College of Medicine in Canton.
"Previous research showed a clear benefit for women who receive Aromasin
after two to three years of tamoxifen," he tells WebMD. "The new
findings show that Aromasin is also effective after five years of
The study, presented at the San Antonio Breast Cancer Symposium, included
nearly 1,500 postmenopausal women who after five years of taking tamoxifen were
followed for the next 30 months.
How the Drugs Work
About 70% of women with breast cancer have tumors that are fueled by
estrogen, making hormone therapy a cornerstone of regimens to prevent
recurrences and improve survival.
For more than 25 years, doctors have been using tamoxifen (an antiestrogen)
to deprive breast cancer cells of the estrogen which they need to grow. But
after five years of treatment, the benefits of tamoxifen decrease.
Newer drugs known as aromatase inhibitors, such as Aromasin, block an enzyme
the body uses to make estrogen, slashing the body's production of estrogen and
depriving hormone-receptor-positive breast cancer cells.
Studies over the past five years have consistently shown that aromatase
inhibitors shrink tumors better with fewer side effects, Mamounas says.
Aromasin isn't the first aromatase inhibitor to benefit women who complete
In 2003, a landmark trial was halted prematurely when Femara, given after
tamoxifen therapy, was shown to result in a lower breast cancer recurrence rate
when compared with women who do not take Femara after tamoxifen. Now Femara is
routinely offered to such women.
The new findings show that women have two options after five years of
tamoxifen therapy, Mamounas says.
That's important because some women can't tolerate one drug or the other,
says Kathy Albain, MD, a breast cancer specialist at Loyola University of
Chicago Medical Center who was not involved with the work.
Femara remains the standard of care after five years of tamoxifen, she says,
as it was tested in a more robust, larger, and longer study.
"These data give us some confidence that we can give Aromasin to these
patients and still achieve good results," Albain tells WebMD.
Aromasin Side Effects
Results of the new trial showed that certain groups of women particularly
benefited from Aromasin therapy, including those younger than 60, those with
small tumors (less than 2 centimeters in diameter), and those who received
The drug was generally well tolerated, but women taking Aromasin had side
effects related to the drops in estrogen that are consistent with the effects
of the drug including joint pain, bone pain, and fatigue.
While the researchers note that estrogen-depleting drugs, including
aromatase inhibitors, have been linked to an increased risk of osteoporosis
and bone problems, similar numbers of women in both groups experienced