Femara May Be Better Than Tamoxifen
Side Effects of Breast Cancer Drugs May Determine Choice
Dec. 28, 2005 - It's official: Femara beats tamoxifen in preventing
A large 27-nation clinical trial shows that postmenopausal women with
estrogen-receptor-positive breast cancer are less likely to get new breast
cancers -- especially cancers in distant parts of the body -- if they take
Femara than if they take tamoxifen.
"Particularly notable was our finding of a significant [27%] reduction
in the risk of distant recurrence with Femara as compared with tamoxifen,"
write Beat Thürlimann, MD, and colleagues. Thürlimann, a senior lecturer at the
University of Basel, Switzerland, owns stock in Novartis, which makes Femara.
Novartis is a WebMD sponsor.
We've heard the news before: The New England Journal of Medicine.
Novartis, which makes the drug, and then at a . Now the report on
the Breast International Group (BIG) 1-98 study appears in the Dec. 29 issue of
It's not that tamoxifen didn't work. Cancer-free, five-year survival was
estimated at 84% for women taking tamoxifen -- only 2.6% lower than for Femara.
Yet Femara had a distinct benefit, with a 27% lower risk of metastatic
Tamoxifen Still Has Large Role
Femara is the most potent member of a new class of drugs called aromatase
inhibitors. These drugs almost totally shut down the body's ability to make
estrogen. Estrogen-receptor-positive tumors grow in the presence of estrogen.
Tamoxifen also blocks estrogen's effects, but not in the same way as Femara and
its sister drugs Arimidex and Aromasin.
Other large clinical trials show that Femara and other aromatase inhibitors
fight breast cancer better than tamoxifen, notes an NEJM editorial by
Sandra M. Swain, MD, of the U.S. National Cancer Institute.
"It is clear ... that these trials, with close to 30,000 participants,
consistently demonstrate that treatment with an aromatase inhibitor alone or
after tamoxifen treatment is beneficial," Swain writes.
Choosing a Treatment Plan
Swain says many questions remain:
- How long should treatment last?
- Should patients take tamoxifen before an aromatase inhibitor, or
- Which is best: Femara, Arimidex, or Aromasin?
- Is taking one drug and then another beneficial?
- Do women whose ovaries have been removed benefit from aromatase
And the biggest question is which drug to take. Aromatase inhibitors are
still expensive, brand-name drugs. Tamoxifen is available in generic form and
is much less expensive.
And aromatase inhibitors raise a woman's risk of osteoporosis. In the BIG
1-98 study, women taking Femara had a significantly higher risk of bone
fracture than those taking tamoxifen.
"A woman with osteoporosis wouldn't be a good candidate for Femara,"
Thürlimann told WebMD last May.
Tamoxifen carries its own risks, including deadly blood clots and uterine
Women taking Femara had higher cholesterol and a higher incidence of heart
trouble than women taking tamoxifen. It's not clear whether this is due to a
side effect of Femara or a possible protective effect of tamoxifen.
The bottom line is that the best cancer drug for one woman isn't the best
for another. Women with breast cancer -- and their doctors -- face difficult
choices. The good news is that the choices are getting better and better.