PHILADELPHIA - Raloxifene protects postmenopausal women from developing invasive breast cancer whether they are at high or low risk of developing the disease, according to a new study.
The study, published in the September 1 issue of Clinical Cancer Research, also revealed that the drug appears to reduce risk in women with a family history of breast cancer down to a similar level to women without affected relatives.
Compared with a placebo drug, the study found that use of raloxifene was associated with a 58 percent reduction in breast cancer risk in women without a family history of the disease, and an 89 percent reduction in risk for women with a family history of breast cancer.
But the researchers say they cannot explain why protection seems greatest in women who may be genetically predisposed to develop the disease.
"We don't know what to make of this observation," said Marc E. Lippman, M.D., professor in the Department of Internal Medicine at the University of Michigan and the study's lead author. "It could be due to chance, or there may be other factors at work that we don't know about."
"But our bottom-line analysis as to why raloxifene universally reduces the risk of developing invasive cancer in women without a family history is that it interferes with the duration and concentration of estrogen, which acts as a tumor promoter in the majority of breast cancers," said Dr. Lippman.
The research team conducted a new analysis of the first large study of raloxifene, which tested the ability of the drug to prevent vertebral fractures in 7,705 postmenopausal women diagnosed with osteoporosis.
The secondary endpoint of this multi-center, double-blind trial, known as MORE (Multiple Outcomes of Raloxifene Evaluation) was the drug's effect on breast cancer
development; results, announced in 1999, demonstrated a 72 percent reduction in invasive breast cancer incidence after four years of raloxifene tr
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Contact: Warren Froelich
froelich@aacr.org
215-440-9300
American Association for Cancer Research
13-Sep-2006