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There are currently no Cancer Prevention Trials available at CCMB.

The Clinical Investigations Office (CIO) at CancerCare Manitoba (CCMB) has been actively involved in conducting cancer prevention trials for breast cancer since 1992. The three prevention trials we have participated in are outlined below:

BCPT

The first large scale Breast Cancer Prevention Trial (BCPT) conducted in North America in the 1990's by the National Surgical Adjuvant Breast and Bowel Project (NSABP) to determine the worth of tamoxifen for preventing breast cancer. Manitoba accrued 140 of the 13,388 women who participated in this study. Study results released in April 1998 showed a 49% reduction in breast cancer among the high risk women who took tamoxifen.

THE STAR TRIAL

STAR, a Study of Tamoxifen and Raloxifene, is one of the largest breast cancer prevention clinical trials ever conducted. The study enrolled 19,490 post menopausal women at increased risk for the disease. Manitoba accrued 139 participants for this study. STAR opened at CCMB in July 1999 and closed October 2004. This trial is also coordinated by the NSABP.

Results to April 15, 2010 indicate that raloxifene retained 76% of the effectiveness in preventing invasive disease and grew closer to tamoxifen in preventing noninvasive disease, while remaining less toxic. However, tamoxifen remains superior to raloxifene in reducing the risk of both invasive and non-invasive breast cancer among postmenopausal women at increased risk.

EXCEL TRIAL

The ExCel research study is coordinated by the NCIC Clinical Trials Group and is a phase III breast cancer prevention clinical trial. It is designed to determine whether Exemestane can prevent breast cancer in healthy postmenopausal women at increased risk for developing breast cancer.

The study opened in May 2005 at CCMB and closed to entry March 2010. NCIC has reached its recruitment goal of 4560 women entered in the study. Manitoba has entered 103 participants.

Trial results were released in June 2011.

Exemestane, an oral anti-estrogen demonstrated a 65% relative reduction in the incidence of invasive breast cancer compared to the placebo control with no serious toxicity and minimal quality of life differences. This is a very significant improvement over tamoxifen or raloxifene, which had been the agents used for breast cancer prevention. Both reduced breast cancer incidence by about 50% but had significant side effects, and therefore had been little used in this preventative role.

It is important to note that despite the positive trial results, Health Canada, the FDA and European regulatory authorities have not as yet approved the sale or use of exemestane for breast cancer prevention, although they did approve its use for the amended study.

The plan will be to carry on with 5 full years of exemestane in the treated participants, and to follow yearly for toxicity assessments. Those who have been on placebo have been informed and offered exemestane for 5 years.

Women in Manitoba are playing a major role in finding ways to reduce the risk of developing breast cancer in high risk women. These women are paving the way for better health in future generations and help to place CCMB at the forefront of research in breast cancer prevention.