Results from cancer study show osteoporosis drug raloxifene is as effective as tamoxifen in preventing breast cancer

Monday, April 17, 2006

Initial results from one of the largest studies of breast cancer prevention ever undertaken in North America show that an osteoporosis drug used to treat postmenopausal women works as well as tamoxifen in reducing the likelihood of developing breast cancer. The University of Texas Health Science Center at Tyler participated in this study.

The Study of Tamoxifen and Raloxifene, or STAR, compared tamoxifen, a drug proven to reduce the chance of breast cancer, with raloxifene, used to treat osteoporosis in postmenopausal women.

Both drugs reduced the risk of older, high-risk women developing invasive breast cancer by about 50 percent, study results show. In addition, women who were randomly assigned to take raloxifene daily, and who were followed for an average of four years, had 36 percent fewer uterine cancers and 29 percent fewer blood clots than women who took tamoxifen. Uterine cancers are a rare but serious side effect of tamoxifen. Both tamoxifen and raloxifene are known to increase the risk of blood clots.

UT Health Science Center was one of more than 500 institutions in the United States, Puerto Rico, and Canada – and the only one in Northeast Texas – to participate in the study. Dr. Patti Olusola is principal investigator for the study at UTHSCT. STAR was sponsored by the National Cancer Institute, part of the National Institutes of Health, and coordinated by the National Surgical Adjuvant Breast and Bowel Project, a network of cancer research professionals.

“It appears that raloxifene has fewer serious side effects than tamoxifen. That is great news, because women currently at risk of breast cancer have only one option – tamoxifen. The Food and Drug Administration has not yet approved raloxifene for breast cancer prevention, but approval of raloxifene will give women at risk for breast cancer the opportunity to take a drug with fewer side effects,” Dr. Olusola said.

UTHSCT enrolled 21 women in the five-year study, she said. Neither the women nor study investigators have known which drug each woman received.

“Some women are finished with their five years, and others aren’t. We have women in all stages of the trial. On Thursday, we will be informing them which drug they are taking and also discussing their options with them,” Dr. Olusola said.

Women who are currently on tamoxifen will be given the option to change to raloxifene for the rest of the five years, she said. Women on raloxifene will continue to receive that drug. In addition, women in the study will continue to be followed after the trial ends to evaluate the long-term benefits of this five-year treatment, Dr. Olusola said.

STAR recruited a total of 19,747 postmenopausal women who were at high-risk for breast cancer. The Health Center enrolled 21 participants in STAR; 1,624 women in Texas participated in the study. About 11,200 cases of female invasive breast cancer are diagnosed in Texas each year, and almost 2,500 women die from the disease, according to the Texas Department of State Health Services.

Participants in STAR were randomly assigned to receive either 60 milligrams of raloxifene or 20 milligrams of tamoxifen daily for five years. Women who participated in STAR were postmenopausal, at least 35 years old, and had an increased risk of breast cancer as determined by their age, family history of breast cancer, personal medical history, age at first menstrual period, and age at first live birth.

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