Hope on the Horizon for Advanced Breast Cancer
New Treatments Are Prolonging Survival and Improving Quality of Life
The female hormone estrogen stimulates the growth of breast
cells, including cancerous cells. So drugs that block estrogen in various ways
can combat cancers that are estrogen receptor positive (ER+). In essence, the
drugs "starve" the abnormal cells of the estrogen they need to
proliferate. Tamoxifen (brand name Nolvadex) is the best known hormone therapy.
It was the first anti-estrogen drug available for use for treating advanced
breast cancer, and it works by selectively blocking estrogen's effects on
breast cancer cells. (These types of drugs are called SERMs.) Another drug,
Fareston, works similarly to Tamoxifen, and is available to treat advanced
breast cancer. Unfortunately, not all breast cancers respond to SERMs, and
others become resistant to this treatment over time.
But now, a new type of anti-estrogen drug is available. Three
of these drugs are currently available -- Arimidex, Femara and Aromasin -- and
each is taken in pill form. These medications promise more options for women
with advanced disease -- even for those whose cancer has become resistant to
In fact, Arimidex and Femara are now approved for initial use
in postmenopausal women with advanced breast cancer, rather than as a
second-line of defense after Tamoxifen has failed. Arimidex has also been
approved as adjuvant therapy -- drugs given after surgery or radiation -- for
women with certain types of early breast cancer.
Aromatase inhibitors work differently than
Tamoxifen; they actually lower the amount of estrogen the body produces.
There's also evidence that they may be more effective drugs. The landmark ATAC
study recently showed that Arimidex was significantly more effective than
Tamoxifen in post-menopausal women with early breast cancer, and several
studies have indicated that aromatase inhibitors cause less toxicity and fewer
side effects than Tamoxifen.
"In terms of hormonal therapies, we now
have a significant number of agents available, with new ones appearing all the
time, and we can sequence them," says Isaacs.
Another anti-estrogen drug, Faslodex, is
representative of a whole new class of drugs that work by destroying the
estrogen receptors in cancerous breast cells. Faslodex was approved by the FDA
and is now available. It's given as an injection and is approved for use in
women with ER+ Tamoxifen-resistant metastatic breast cancer. At least one study
shows that it may also be helpful for women who have previously received other
hormonal treatments in addition to Tamoxifen, such as aromatase
Earlier versions of hormone therapy
sometimes caused nausea, bleeding and blood clots, but those side effects have
been reduced significantly with the newer drugs. "Quality of life with
these drugs is much better and the side effects are much more tolerable,"