| CHICAGO, June 1
CHICAGO, June 1 The estrogen-blocking drug
Aromasin worked better than the long-standing therapy tamoxifen
at keeping cancers from returning in younger women with early
stage breast cancer, a finding that may change the way the
patients are treated, U.S. researchers said on Sunday.
Aromasin, a drug developed by Pfizer Inc that is
sold generically as exemestane, is in a class of treatments
called aromatase inhibitors that are typically used in
post-menopausal women with low levels of estrogen.
Aromatase is an enzyme that converts the hormone androgen
into small amounts of estrogen.
The drugs have largely been off-limits for younger women
with working ovaries that produce estrogen.
In premenopausal women with hormone-sensitive cancers, the
standard for preventing recurrence is five years of treatment
with a drug called tamoxifen. For high-risk women, doctors in
some countries recommend exemestane plus some form of therapy to
shut down the ovaries, cutting off the supply of estrogen. That
practice is not typically followed in the United States because
there has not been enough evidence to show a benefit.
International researchers tested whether aromatase
inhibitors combined with ovary-blocking treatments would do a
better job than tamoxifen in two clinical trials involving 4,690
All women in the studies underwent some treatment to block
the function of their ovaries, either through a drug called
triptorelin, the surgical removal of the ovaries or the use of
radiation. In addition, one group tested exemestane and the
other tested tamoxifen.
A joint analysis of the two international trials known as
SOFT and TEXT, presented at the American Society of Clinical
Oncology, or ASCO, meeting in Chicago, showed exemestane did a
better job of keeping cancer at bay when women's ovarian
function was suppressed, said Dr. Olivia Pagani of the Oncology
Institute of Southern Switzerland.
Her study was presented at the meeting and will be published
this week in the New England Journal of Medicine.
Dr. Clifford Hudis, a breast cancer expert and president of
ASCO, said that with ovarian suppression, aromatase inhibitors
offered an option for further cutting the risk of recurrence.
But some questions remain.
Although aromatase inhibitors showed a benefit in preventing
recurrence, the researchers have yet to present data showing
whether the treatment also extends survival compared with
It is also still not clear whether shutting down the ovaries
adds a benefit to women who are being treated with tamoxifen
alone, which is the current standard of care in the United
"Based on these results, the answer is likely yes," said Dr.
Claudine Isaacs, co-director of the Breast Cancer Program at
Georgetown Lombardi Comprehensive Cancer Center.
But she said suppressing ovarian function "is not
negligible." It puts women into menopause, accompanied by all of
the side effects, including hot flashes, vaginal dryness, bone
loss and possible increased risk for heart disease.
Results of that arm of the study are expected later this
(Reporting by Julie Steenhuysen; Editing by Peter Cooney)