Updated
Results Indicate Improved Survival with Femara ® in Breast
Cancer
According to results recently presented at the 40th annual
meeting of the American Society of Clinical Oncology (ASCO),
updated results indicate that Femara ® (letrozole) following
tamoxifen (Nolvadex ®) reduces the risk of death by nearly
40% in postmenopausal women with hormone-positive early breast
cancer.1
Early-stage breast cancer refers to cancer that has not spread
from its site of origin. Patients with early-stage breast
cancer may have cancer that has spread to axillary (under
the arm) lymph nodes, but not to distant sites in the body.
Standard treatment for early-stage breast cancer depends upon
several differing factors, such as the extent of spread of
disease (i.e. the size of the cancer and/or number of involved
lymph nodes), age of the patient, hormone status of the cancer,
overall health of the patient and/or aggressiveness of the
cancer. Following the surgical removal of the cancer, some
undetectable cells may remain in the body that are responsible
for cancer recurrences and ultimately, reduced survival. Therefore,
standard therapeutic approaches for early-stage breast cancer
often include radiation therapy, hormone therapy and/or chemotherapy
in an attempt to kill the remaining cancer cells.
Hormone-positive breast cancer refers to a common type of
cancer that is stimulated to grow from the female hormones
estrogen (ER) and/or progesterone (PR). Patients with hormone-positive
breast cancer are often offered hormonal therapy, a type of
therapy that reduces the production or the stimulatory growth
effects of estrogen. Tamoxifen has historically been the standard
agent used for hormonal therapy in women with hormone-positive
breast cancer and is typically used for 5 years. Tamoxifen
works by binding to estrogen receptors in a cell so that estrogen
is unable to bind, ultimately reducing its growth-stimulatory
effects. Recently, however, newer agents referred to as aromatase
inhibitors have entered the clinical arena. These agents work
by inhibiting the enzyme (protein) aromatase, which is involved
in the production of estrogen in the body. Clinical trials
are ongoing in an attempt to answer many questions regarding
the role of aromatase inhibitors in the treatment of breast
cancer, including the timing and sequencing in conjunction
with tamoxifen.
The clinical trial, referred to as the MA-17 trial, included
over 5,000 postmenopausal women who had completed 5 years
of treatment with tamoxifen. Approximately half of these women
went on to receive either Femara ® or placebo (inactive
substitute) and were directly compared. Earlier results from
this trial demonstrated a significant reduction in cancer
recurrences by 43% in the group of women treated with Femara ®
compared to placebo.2 More patients treated with Femara ®
had a reduced quality of life compared to those treated with
placebo, including increased bodily pain, hot flashes, pain
in the joints and muscles, osteoporosis, and reduced energy
and vitality. 3 However, a large proportion of patients considered
the side effects to be worth the reduced risk of a recurrence.
This trial was stopped prematurely due to the obvious benefits
of treatment with Femara ® compared to placebo. At the
2004 ASCO meeting, updated survival results were presented
from this trial. Overall, the group of women treated with
Femara ® had an 18% reduced risk of death than those who
received placebo. Women with cancer that had spread to the
lymph nodes (node-positive) had a 39% reduced risk of death
if treated with Femara ® compared to placebo. Furthermore,
the risk of a recurrence was also reduced by approximately
40% in all women treated with Femara ® compared to placebo.
These results indicate that the addition of Femara ® following
5 years of tamoxifen significantly reduces the risk of death
and cancer recurrence in women with breast cancer, with node-positive
patients gaining the greatest survival benefit. Clinical trials
are ongoing to determine the optimal timing and sequencing
of aromatase inhibitors and tamoxifen in the treatment of
hormone-positive breast cancer. Postmenopausal patients with
hormone-positive breast cancer may wish to speak with their
physician about the risks and benefits of continued Femara ®
following tamoxifen in their treatment regimen, or the participation
in a clinical trial further evaluating the role of aromatase
inhibitors. Two sources of information regarding ongoing clinical
trials include the National Cancer Institute (cancer.gov)
and www.cancerconsultants.com. Personalized clinical trial
searches are also performed at cancerconsultants.com.
References:
1. Goss P, Ingle J, Martino S, et al. Updated analysis of
the NCIC CTC MA.17 randomized placebo (P) controlled trial
of letrozole (L) after five years of tamoxifen in postmenopausal
women with early stage breast cancer. Proceedings from the
40th annual meeting of the American Society of Clinical Oncology.
New Orleans, LA. 2004. Abstract #847. “Best of oncology
symposium” presented June 8, 2004.
2. Goss P, Ingle J, Martino S, et al. A randomized trial
of letrozole in postmenopausal women after five years of tamoxifen
therapy for early-stage breast cancer. The New England Journal
of Medicine. Early publication available at: www.nejm.org.
October 9, 2003.
3. Goss, et al. A randomized trial of letrozole in postmenopausal
women after five years of tamoxifen therapy for early-stage
breast cancer. Proceedings from the 2003 San Antonio Breast
Cancer Symposium. December 2003.
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