ROCKVILLE, MarylandThe US Preventive Services Task Force (USPSTF) has
recommended against the use of tamoxifen (Nolvadex) and raloxifene (Evista) for
the primary prevention of breast cancer in women at low or moderate risk of the
disease. Tamoxifen is currently approved for use as chemoprevention in
high-risk women. The panel urged physicians to fully discuss chemoprevention
with their high-risk patients and inform them of the risks and benefits of
using the drugs.
"The task force found fair evidence that tamoxifen can significantly
reduce the risk of invasive estrogen-receptor-positive breast cancer by
approximately 50% in women at high risk of the disease," said Janet Allan,
PhD, RN, the group’s vice chair. "We found consistent evidence for
raloxifene, but it was limited to one study that focused on the use of the drug
to prevent fractures."
USPSTF is an independent group of experts sponsored by the Agency for Health
Care Research and Quality (AHRQ) that makes recommendations across the
prevention spectrum. It based its recommendations on a review led by Linda
Kinsinger, MD, and Russell Harris, MD, of AHRQ’s Evidence-based Practice
Center at RTI International-University of North Carolina.
Tamoxifen is the only drug FDA approved for breast cancer risk reduction.
However, some research suggests that raloxifene may also reduce a woman’s
risk of the disease. Raloxifene is FDA approved for the prevention and
treatment of osteoporosis, and some clinicians prescribe it off-label for
breast cancer risk reduction.
The STAR Trial
Currently, researchers are accruing 22,000 postmenopausal women age 35 or
older who are at increased risk of breast cancer for the Study of Tamoxifen and
Raloxifene (STAR). This ongoing trial, supported by the National Cancer
Institute, is designed to compare the safety and efficacy of the two drugs. In
the first 3 years of the study, researchers at more than 500 sites in the
United States, Puerto Rico, and Canada enrolled 13,647 women. Enrollment is
scheduled to continue through June 2004.
The task force based its recommendation against use of the two drugs for
chemoprevention in low- and moderate-risk women on the potential for harmful
side effects that might not outweigh their benefit in reducing breast cancer.
These adverse effects include hot flashes and an increased risk of blood clots
in the legs and lungs. Tamoxifen also increases a woman’s risk of endometrial