Femara ®
Improves Anti-Cancer Responses over Arimidex ® in Advanced
Breast Cancer
According to a recent article published in the European Journal
of Cancer, the anti-aromatase agent Femara ® produces higher
anti-cancer response rates than Arimidex ® in hormone-positive,
advanced breast cancer. However, there were no differences
in cancer recurrences or survival between the two agents.
Breast cancer claims the lives of approximately 40,000 women
annually in the United States alone. A common type of breast
cancer, referred to as hormone-positive breast cancer, is
stimulated to grow from the female hormones estrogen and/or
progesterone. Women with hormone-positive breast cancer are
treated with agents that block the growth-stimulatory effects
of hormones on cancer cells. The new generation of agents
that has recently been approved for the use of hormone-positive
breast cancer is the aromatase agents. Aromatase agents block
the development of estrogen in the body, by inhibiting the
enzyme aromatase. Aromatase is crucial for the production
of biologically active estrogen. At present, aromatase agents
are being evaluated in different stages of breast cancer and
are being compared to each other in the treatment of hormone-positive
breast cancer.
Femara ® (letrozole) and Arimidex ® (anastrozole) are
two aromatase agents that have been approved by the FDA for
treatment of hormone-positive breast cancer. Femara ® is
approved as initial therapy for postmenopausal women with
hormone-positive, or hormone status unknown, locally advanced
or metastatic breast cancer, or as second-line therapy in
this group of patients who have experienced disease progression
following treatment with an anti-estrogen. Arimidex ® is
approved as therapy for postmenopausal women with early-stage
breast cancer that is hormone positive. It is also approved
for therapy in hormone-positive, postmenopausal women with
advanced breast cancer, either as initial or second-line therapy.
Recently, researchers conducted a clinical trial to compare
Femara ® to Arimidex ® in patients who had cancer progression
following prior therapy with Nolvadex ®. This trial included
713 postmenopausal women with advanced breast cancer who were
treated with either Femara ® or Arimidex ® as second-line
therapy. Approximately half of the patients had estrogen and/or
progresterone-positive breast cancer, while the other half
had unknown hormone status. Overall anti-cancer response rates
were achieved in 19.1% of patients treated with Femara ®,
compared with only 12.3% of patients treated with Arimidex ®.
However, the average time to cancer progression was 5.7 months
in both groups of patients and overall survival was approximately
21 months for both groups of patients. Both drugs were well
tolerated and had similar side effects.
The researchers concluded that Femara ® produces a higher
rate of anti-cancer responses than Arimidex ® in postmenopausal
women with advanced breast cancer that has progressed following
Nolvadex ® therapy. However, the average durations of time
to cancer progression and overall survival were similar between
the two agents. Longer follow-up may reveal some differences
in outcomes. Postmenopausal women with hormone-positive breast
cancer may wish to speak with their physician about the risks
and benefits of participating in a clinical trial further
evaluating aromatase agents or other promising therapeutic
approaches. Two sources of information regarding ongoing clinical
trials include the National Cancer Institute ( cancer.gov)
and www.cancerconsultants.com.Personalized clinical trial
searches on behalf of patients are also performed at cancerconsultants.com.
Reference: Rose C, Vtoraya O, Pluzanska A, et al. An Open
Randomised Trial of Second-Line Endocrine Therapy in Advanced
Breast Cancer. European Journal of Cancer. 2003;39:2318-2327.
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