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Senior Citizen Health & Medicine
Aromatase Inhibitors Lead in Improved Survival with
Metastatic Breast Cancer
Aromatase inhibitors help block tumor growth by
lowering estrogen
July 23, 2007 - Newer drugs available since the 1990’s, in
particular aromatase inhibitors, have improved the survival of women
with metastatic breast cancer, according to a report to appear in the
September 1, 2007 issue of CANCER, a peer-reviewed journal of the
American Cancer Society. Survival improved by approximately 30 percent
as systemic therapy became more widely used.
Currently, women with metastatic breast cancer
survive an average of approximately 24 months. That marks a significant
improvement from the estimated 18 month survival noted in the early
1980s.
While popular opinion has suggested that this
improved survival rate is due to newly developed drugs, a direct link
has not been clearly shown prior to this study.
Dr. Stephen Chia of the University of British
Columbia in Vancouver and co-investigators compared outcomes of 2150
women diagnosed with metastatic breast cancer in the Canadian province
of British Columbia between 1991 and 2001.
In analyzing temporal trends in outcome, the
investigators’ primary goal was to evaluate whether new hormonal and
chemotherapeutic drugs approved for public use actually had an impact on
survival outside the clinical trial setting. In addition, because not
all patients in the general population received any palliative systemic
therapy, they were also able to make inferences about drug efficacy
versus no treatment.
Significantly, they found that new drugs did have a
significant positive effect on survival for women with metastatic
disease in the latter half of the 1990s.
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About Aromatase Inhibitors
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By National Cancer Institute
Many
breast tumors are "estrogen sensitive," meaning the hormone estrogen
helps them to grow. Aromatase inhibitors (AIs) can help block the growth
of these tumors by lowering the amount of estrogen in the body.
Estrogen is produced by the ovaries and other tissues of the body, using
a substance called aromatase. AIs do not block estrogen production by
the ovaries, but they can block other tissues from making this hormone.
That's why AIs are used mostly in women who have reached
menopause, when the ovaries are no longer producing
estrogen.
Another drug, tamoxifen (Nolvadex®), also helps to prevent the growth of
estrogen-sensitive breast tumors, but it works differently from AIs.
Whereas AIs reduce the amount of estrogen in the body, tamoxifen blocks
a tumor's ability to use estrogen.
Currently, three AIs are approved by the U.S. Food and Drug
Administration:
anastrazole (Arimidex®),
exemestane (Aromasin®), and
letrozole (Femara®).
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More from National Cancer Institute
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Median survival remained unchanged between the
1991-1992 and 1994-1995 groups, at only 438 days in the first and 450
days in the second time period.
As new drugs, in particular the aromatase
inhibitors, became available on the formulary and more commonly used for
women with first metastases in the mid-1990s, survival further increased
to 564 days (1997-1998 group) to 667 days (1999-2001 group).
Dr. Chia and co-authors wrote, “our
population-based study of a large cohort of women with a recent
diagnosis of metastatic breast cancer is the first to demonstrate a
significant improvement in survival over time.”
While the study does not definitively attribute
these improvements to a single therapy, “the greatest differences in
survival were associated with the introduction of the aromatase
inhibitors, docetaxel (Taxotere®) and trastuzumab (Herceptin®) in the
later two cohorts,” they conclude. FDA approve aromatase inhibitors
include anastrazole (Arimidex®), exemestane (Aromasin®), and letrozole (Femara®)
Editor’s Notes:
Article: “The Impact of New Chemotherapeutic and
Hormone Agents on Survival in a Population-based Cohort of Women with
Metastatic Breast Cancer,” Stephen K. Chia, Caroline H. Speers, Yulia
D’yachkova, Anna Kang, Suzanne Malfair-Taylor, Jeff Barnett, Andy
Coldman, Karen A. Gelmon, Susan E. O’Reilly, Ivo A. Olivotto, CANCER;
Published Online: July 23, 2007 (DOI: 10.1002/cncr. 22867); Print Issue
Date: September 1, 2007.
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