Letrozole
Following Tamoxifen Improves Cancer-Free Survival in Early
Breast Cancer
According to a recent article published in The New England
Journal of Medicine, letrozole (Femara ®) following 5 years
of tamoxifen (Nolvadex ®) improves cancer-free survival
in postmenopausal women with hormone-positive, early breast
cancer.
Early-stage breast cancer refers to cancer that has not spread
from its site of origin. Patients with early-stage breast
cancer may have 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.
Recently, researchers conducted a clinical trial to evaluate
the aromatase inhibitor letrozole following tamoxifen in women
with early-stage breast cancer. This trial involved over 5,000
postmenopausal women with hormone-positive breast cancer,
who had completed 5 years of treatment with tamoxifen. Approximately
half of the women then received either letrozole or placebo
(inactive substitute) and were directly compared. At an average
of almost 2 years following initiation of the trial, cancer
recurrences or a new cancer in the other breast occurred in
only 75 patients treated with letrozole, compared to 132 receiving
placebo. Cancer-free survival at 4 years is estimated to be
93% for the group treated with letrozole, compared with 78%
for those receiving placebo. Side effects of letrozole include
an increased risk of osteoporosis (reduced bone density),
muscle and joint aches, and menopausal symptoms such as hot
flashes.
The researchers concluded that treatment with letrozole following
5 years of tamoxifen appears to improve cancer-free survival
in postmenopausal women with hormone-positive, early breast
cancer. Clinical trials are ongoing to determine if aromatase
inhibitors used prior to tamoxifen in different stages of
breast cancer, as well as in the preventive setting, may provide
an even greater benefit. Postmenopausal women with hormone-positive
breast cancer may wish to speak with their physician about
the use of letrozole following standard tamoxifen therapy.
Reference: 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.
© CancerConsultants.com
|
