By Amanda Gardner
WEDNESDAY, June 11 (HealthDay News) -- A drug already approved to reduce the risk of breast cancer in high-risk women also seems to cut the risk for other women.
A new analysis finds that those who took raloxifene (Evista) regularly over a number of years were less likely to develop invasive estrogen-receptor (ER) positive breast cancer, compared with women who did not take the drug.
Raloxifene did not, however, cut the risk for noninvasive breast cancer or invasive ER-negative cancers.
"This is a reaffirmation that the drug raloxifene is a very powerful SERM [selective estrogen receptor modulator] for reducing the risk of invasive breast cancer," said Dr. Jay Brooks, chief of hematology/oncology at Ochsner Health System in Baton Rouge, La.
The study, published in the June 10 online issue of the Journal of the National Cancer Institute, was funded by Eli Lilly and Co., which makes Evista.
SERMs block the female hormone estrogen by binding to estrogen receptors; estrogen helps fuel the growth of some breast cancers. Raloxifene and other hormonal therapies have an "estrogenic tickle" effect, explained V. Craig Jordan, author of an accompanying editorial in the journal and vice president and research director for medical science at Fox Chase Cancer Center in Philadelphia. Jordan did some of the early laboratory research on raloxifene.
Raloxifene was originally developed to prevent and treat osteoporosis, and only later was found to help reduce the risk of invasive breast cancer in high-risk women.
The new study expands on the original results of the RUTH (Raloxifene Use for the Heart) trial, originally designed to see if raloxifene, which has cholesterol-lowering properties, could reduce the risk of dying from coronary heart disease.
The trial involved more than 10,000 postmenopausal women with coronary heart disease or at risk for the condition. Participants were randomly chosen to receive either daily raloxifene or a placebo and followed for a median of 5.6 years.
Raloxifene turned out not to have any effect on heart disease mortality risk, but it did reduce the risk of invasive breast cancer by 44 percent, which translates into 1.2 women per 1,000 treated for one year who were spared the agony of a breast cancer diagnosis.
The new analysis looked more specifically at raloxifene's effect on breast cancer and found a 55 percent lower incidence of invasive ER-positive tumors, but no effect on noninvasive breast cancer or invasive ER-negative breast cancer.
According to the study authors, these findings are consistent with results from other trials involving women without heart disease. This trial and others found an increased risk of blood clots and fatal strokes among women taking raloxifene, indicating that women need to weigh the risks and benefits of the drug.
Another question is how long to take raloxifene for breast cancer prevention, although the authors speculated that up to eight years might be safe and effective.
"We're learning more about this class of drugs, what works and what doesn't work," Jordan said. "[Raloxifene] is good for osteoporosis, no good for coronary heart disease, but breast cancer is inhibited."
The U.S. National Cancer Institute has more on SERMs and how they work.