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Adjuvant Aromatase Inhibitor Therapy for Breast Cancer
Untitled Document
Name of the Trial
Phase III Randomized Adjuvant Study of Exemestane Versus Anastrozole in Postmenopausal
Women with Receptor-Positive Primary Breast Cancer (CAN-NCIC-MA27). See the
protocol summary.
Principal Investigators
Dr. Paul Goss (Study Chair) and Dr. Kathleen Pritchard, NCIC-Clinical
Trials Group; Dr. James Ingle, NCCTG;
Dr. Matthew Ellis, CALGB; Dr. George Sledge,
ECOG; Dr. George Budd, SWOG;
and Dr. Manuela Rabaglio, IBCSG.
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Dr. Paul Goss
Principal Investigator |
Why This Trial Is Important
Aromatase inhibitors (AIs) have emerged as an important treatment option for
postmenopausal women with hormone receptor-positive
breast cancer. AIs interfere
with the body's ability to make the hormone estrogen, which can fuel the growth
of breast cancer cells that have estrogen receptors. AIs
block the activity
of an enzyme called aromatase, which is necessary to make estrogen.
Anastrozole (Arimidex) and exemestane (Aromasin) are two
AIs approved by the
FDA to treat early-stage, hormone receptor-positive breast cancer. Anastrozole
is a reversible inhibitor that competes with estrogen precursor molecules for
binding to aromatase; exemestane attaches permanently to aromatase, preventing
estrogen precursors from binding to the enzyme at all (making it an irreversible
"suicide" inhibitor). Exemestane also exerts androgenic (male hormone-like)
effects in women, and this may contribute to its anticancer efficacy while possibly
causing fewer side effects.
In this clinical trial, postmenopausal women with hormone receptor-positive
breast cancer that has been surgically removed will be randomly assigned to
receive either anastrozole or exemestane for 5 years. Doctors will monitor breast
cancer recurrence and the side effects of these drugs.
Separate companion studies
will examine whether there is a difference in how the drugs affect bone mineral
density and breast density in these patients; only those locations enrolling
patients in the breast density companion study (NCCTG-N0434)
are currently accepting patients for the AI study.
"While anastrozole and exemestane have not been compared previously in
a clinical trial, evidence from preclinical studies and other clinical trials
comparing each agent to tamoxifen support the idea that exemestane may be a
more potent inhibitor of aromatase and have androgenic effects that may be important
in enhancing efficacy and affording a better side effect profile," Dr.
Goss said.
For More Information
This trial is no longer recruiting new patients. To locate other breast
cancer clinical trials, search the NCI's database
of clinical trials or call the NCI's Cancer Information Service at 1-800-4-CANCER
(1-800-422-6237). The call is toll free and completely confidential.
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