"Although no drugs are without side effects, tamoxifen and raloxifene are vital options for women who are at increased risk of breast cancer and want to take action," said Leslie Ford, M.D., associate director for clinical research in NCI's Division of Cancer Prevention. "For many women, raloxifene's benefits will outweigh its risks in a way that tamoxifen's benefits do not."

The STAR researchers also tracked known menopausal side effects that occur with both drugs and monitored the participants' quality of life. The data show that side effects of both drugs were mild to moderate in severity, and quality of life was the same for both drugs.


Participants in STAR are now receiving information about which drug they were taking. Women assigned to raloxifene will continue to be provided with the drug until they have completed five years of treatment. Those women assigned to tamoxifen can choose to continue taking tamoxifen or to receive raloxifene to complete their five years of treatment.

Study details include:

* STAR enrolled 19,747 women. This data analysis is based on the 19,471 women for whom complete study information was available.

* The numbers of invasive breast cancers in both groups of women were statistically equivalent. Among the 9,745 women in the raloxifene group, 167 developed invasive breast cancer, compared to 163 of 9,726 women in the tamoxifen group.

* More than half of the women who joined STAR had had a hysterectomy and, therefore, were not at risk of uterine cancer. For those women with a uterus, 36 of 4,732 who were assigned to take tamoxifen developed uterine cancers (mainly endometrial cancer) compared to 23 of 4,712 women who were assigned to take raloxifene.

* In STAR, women in the raloxifene group had 29 percent fewer deep vein thromboses (blood clots in a major vein) and pulmonary embolisms (blood clots in the lung) than women in the tamoxifen group. Specifically, 87 of 9,726 women in the tamoxifen group had a deep vein thrombosis compared to 65 of 9,745 women taking raloxifene. In addition, 54 of 9,726 women taking tamoxifen developed pulmonary embolisms compared to 35 of 9,745 women taking raloxifene.

* The number of strokes occurring in both groups of women was statistically equivalent: 53 of 9,726 women in the tamoxifen group and 51 of 9,745 women in the raloxifene group had a stroke during the trial. There was no difference in deaths from strokes: 6 of 9,726 women in the tamoxifen group and 4 of 9,745 women in the raloxifene group died from this event. Women at increased risk of stroke (those with uncontrolled hypertension or uncontrolled diabetes, or a history of stroke, transient ischemic attack, or atrial fibrillation) were not eligible to participate in STAR.

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