The largest North American breast cancer prevention trial ever undertaken has reached its goal of enrolling 19,000 women

The largest North American breast cancer prevention trial ever undertaken, the Study of Tamoxifen and Raloxifene (STAR), reached its goal of enrolling 19,000 women to the trial in June 2004, a month earlier than originally expected.

Women still being evaluated for the study will be allowed to join the trial until October. Researchers from the National Surgical Adjuvant Breast and Bowel Project (NSABP) predict that women will know by the summer of 2006 which drug, tamoxifen (marketed under the name Nolvadex) or raloxifene (Evista), is more effective in preventing breast cancer with fewer side effects. More than 500 sites in the United States, Canada and Puerto Rico are involved in STAR.

One of the sites is the Arizona Cancer Center in Tucson. The study's principal investigator is Dr. David S. Alberts, director of cancer prevention and control at the Cancer Center. The co-principal investigator is Dr. Ana María López, an associate professor of clinical medicine at the UA.

According to study coordinator Heidi Fritz, 119 patients have been enrolled in STAR through the Arizona Cancer Center.

"It's a remarkable achievement," said Dr. Norman Wolmark, chairman of the NSABP and the department of human oncology at Allegheny General Hospital in Pittsburgh. "Women at increased risk for developing breast cancer chose to be proactive about finding options to prevent the disease. We owe a debt of gratitude to these women who are leading the charge in preventing breast cancer."

Women participating in STAR are randomly assigned to tamoxifen or raloxifene for five years. They will continue to obtain close follow-up care until study results are known. The STAR study began in 1999, and some women have already completed their five years of treatment.

Tamoxifen, a mainstay in breast cancer treatment, also is approved for breast cancer risk reduction in women with an increased risk of getting the disease. Raloxifene is approved to prevent and treat osteoporosis in postmenopausal women. The initial results of the STAR trial should be available by early 2006.

"Data from these large-scale clinical trials in breast cancer prevention is critically important and will help women at increased risk for breast cancer make choices about their health," said Dr. Leslie Ford, associate director for clinical research in the Division of Cancer Prevention at the National Cancer Institute. "The women who have chosen to join this trial are advancing the medical frontier and should be congratulated."

STAR is conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP), a not-for-profit cancer research group, and is funded primarily by the National Cancer Institute. Eli Lilly in Indianapolis, has provided the raloxifene, and AstraZeneca Pharmaceuticals in Wilmington, Del., has provided the tamoxifen for the trial at no charge.