Drug Switch Ups Breast Cancer Survival
After 2-3 Years of Tamoxifen, Switch to Arimidex May Lower Death Risk
Nov. 17, 2006 -- Postmenopausal breast cancer survivors do best if they
switch to Arimidex after two to three years of tamoxifen therapy.
The finding comes from an analysis of clinical trial data funded by
AstraZeneca, the company that makes Arimidex. AstraZeneca is a WebMD
The study itself was performed by Walter Jonat, MD, of the University of
Kiel, Germany; Michael Gnant, MD, of the University of Vienna, Austria; and
Jonat's team combined data from three studies of postmenopausal women who,
after breast cancer surgery, took
tamoxifen (brand name, Nolvadex) to prevent their cancers from coming back.
After two or three years of tamoxifen therapy, some of these women switched to
In the combined analysis, there were about 2,000 women in each group. Those
who switched to Arimidex did better than those who stayed on tamoxifen:
- The Arimidex group had a 29% lower risk of death.
- The Arimidex group had a 41% higher chance of disease-free survival.
- The Arimidex group had a 45% lower chance of cancer relapse in any part of
Arimidex is in a class of drugs known as nonsteroidal aromatase inhibitors.
Another drug in this class, Femara, is made by Novartis. Aromasin, made by
Pfizer, is a steroidal aromatase inhibitor. Novartis and Pfizer are WebMD
These drugs block an enzyme the body uses to make estrogen, thereby
suppressing estrogen levels throughout the body. After surgery, they help
prevent cancer recurrence in women who have had estrogen-sensitive breast
Some women and their doctors choose to start treatment with aromatase
inhibitors. Many doctors, however, start with tamoxifen and switch to aromatase
inhibitors after five years.
"A lot of people have been waiting to see whether aromatase inhibitors
will show a survival advantage, and I think this data will assure them that
five years of tamoxifen is no longer the standard of care," Jonat said in a
news release. "The best treatment for women with hormone-sensitive
early-stage breast cancer should include an aromatase inhibitor."
Jonat and colleagues note that their analysis is not proof that women should
switch to aromatase inhibitors after two or three years of tamoxifen. Such
proof can come only from clinical trials. Such trials currently are
Jonat and colleagues report their findings in the Nov. 17 online edition of
The Lancet Oncology.