The GISS trial: a phase II prevention trial of screening plus goserelin, ibandronate, versus screening alone in premenopausal women at increased risk of breast cancer.

BACKGROUND Genetic testing for inherited mutations in breast cancer genes provides valuable information for disease prevention. Today, premenopausal women with increased risk for breast cancer have only limited nonsurgical options to reduce their risk. METHODS The GISS trial, a randomized, multicenter, open-label phase II trial, assessed the feasibility of a preventive treatment with goserelin and ibandronate for premenopausal women at increased risk for breast cancer. The primary endpoints were refusal to undergo randomization and discontinuation of treatment. Safety and quality of life were also evaluated. RESULTS Between the years 2001 and 2003, 31 of 322 eligible women participated in the trial; 15 received goserelin/ibandronate plus screening, 15 screening only, and 1 withdrew her consent after randomization. The treatment duration was 24 months. Here, mainly the results from the first 12 months were evaluated because of the low compliance thereafter. Hot flushes, headache, and vaginal dryness/discharge occurred more often in the goserelin arm. No difference was observed between the two arms in the agreement to randomization, compliance, or any other endpoints. CONCLUSIONS Acceptance of chemoprevention with goserelin and ibandronate was low. Premenopausal women at increased risk for breast cancer should be better informed about chemoprevention through physician counseling and a more feasible study design (e.g., oral medication) should be provided. IMPACT This is the first chemoprevention trial in premenopausal women at increased risk for breast cancer.