Indole-3-Carbinol in Preventing Breast Cancer in Nonsmoking Women Who Are at High Risk For Breast Cancer

DISEASE CHARACTERISTICS: Women at high risk for breast cancer, defined by at least 1 of the following criteria: Projected 5-year probability of invasive breast cancer at least 1.66%, as determined by the Breast Cancer Risk Assessment Tool Prior node-negative breast cancer Prior biopsy indicating atypical lobular or ductal hyperplasia or carcinoma in situ Age 60 and over Non-smoker confirmed by urine cotinine test No concurrent breast cancer Hormone receptor status: Not specified PATIENT CHARACTERISTICS: Age: 18 to 70 Sex: Female Menopausal status: Premenopausal (regular menstrual cycles of 24-36 days within the past 6 months) OR Postmenopausal (no menstrual cycle for at least 6 months) Performance status: Not specified Life expectancy: At least 1 year Hematopoietic: Absolute granulocyte count greater than 1,500/mm^3 Hemoglobin greater than 10 g/dL Hepatic: Bilirubin less than 1.8 mg/dL Aspartate aminotransferase (AST) and Alanine transaminase (ALT) less than 110 U/L Alkaline phosphatase less than 300 U/L Albumin greater than 3 g/dL Renal: Creatinine less than 2.0 mg/dL Cardiovascular: No acute or unstable cardiovascular condition based on electrocardiogram Other: Mild seasonal allergies allowed No serious or life-threatening drug allergies No other serious intolerances or allergies No more than 20% above or below ideal body weight No acute or unstable medical condition by physical examination or laboratory tests No chronic headaches, dysphoria, fatigue, dizziness, blurred vision, insomnia, rhinorrhea, nausea, vomiting, abdominal pain, diarrhea, constipation, or similar conditions No serious illness requiring chronic drug therapy No active malignancy Not pregnant or nursing Negative pregnancy test Fertile patients must use effective barrier contraception 1 month before, during, and for 1 month after study PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior chemotherapy Endocrine therapy: At least 2 months since prior hormonal therapy as contraception or hormone replacement therapy (HRT) No concurrent sex hormones as contraception for premenopausal women No concurrent HRT for postmenopausal women Radiotherapy: Not specified Surgery: Not specified Other: At least 6 months since prior investigational drugs At least 1 month since prior weekly consumption of more than 3 medium servings (half cup each) of cruciferous vegetables No concurrent vegetarian diet or weekly consumption of more than 3 medium servings (half cup each) of cruciferous vegetables No continuous supplement intake No recent change in medications or dosage of medications