Genistein in Preventing Breast Cancer in Women at High Risk for Breast Cancer

Inclusion Criteria

• •No known soy intolerance
• •At increased risk of developing breast cancer in \>= 1 previously unaffected breast, as defined by any of the following:
• •* Estimated 5-year risk of developing breast cancer using the Gail model, as defined by 1 of the following:
• •* Gail score \>= 1.66%
• •* Gail score \>= 0.1% for women age 20-29 years
• •* Gail score \>= 1.0% for women age 30-39 years
• •* Estimated 5-year risk of developing breast cancer using the Claus model:
• •* Claus score \>= 1.66%
• •* Claus score \>= 0.1% for women age 20-29 years
• •* Claus score \>= 1.0% for women age 30-39 years
• •* Prior diagnosis of unilateral in situ or invasive breast cancer OR history of atypical hyperplasia, BRCA 1 and/or BRCA 2 positivity
• •* History of lobular carcinoma in situ
• •No evidence of breast cancer, as determined by a negative mammogram within the past 6 months and a history and physical
• •No previously diagnosed breast cancer unless all systemic therapy (including endocrine therapy) was completed at least 1 year ago
• •Pre- or postmenopausal
• •ECOG performance status 0-1
• •Hemoglobin \> 10.0 g/dL
• •Platelet count \> 100,000/mm\^3
• •Absolute neutrophil count \> 1,000/mm\^3
• •Creatinine \< 2.0 mg/dL
• •SGPT \< 82 U/L
• •SGOT \< 68 U/L
• •Bilirubin \< 3 mg/dL\* \[Note: \* Patients with a higher level of bilirubin due to a familial metabolism may be eligible at the discretion of the investigator\]
• •Life expectancy \> 2 years
• •Not pregnant or nursing
• •Negative pregnancy test
• •Fertile patients must use effective barrier contraception
• •Must be willing to keep a dietary diary
• •No venous thrombosis within the past year
• •No unrecognized or poorly controlled thyroid disease
• •No other cancer within the past 5 years except nonmelanomatous skin cancer or noninvasive cervical cancer
• •No other medical condition that, in the opinion of the investigator, would jeopardize either the patient or the integrity of the data obtained
• •None of the following for \>= 2 weeks before the first random fine needle aspiration and during study participation:
• •* Oral contraceptives
• •* Soy supplements
• •* High soy-containing foods
• •* Fish oil supplements
• •* Multivitamins
• •* Vitamins C and E
• •* Daily aspirin or nonsteroidal
• •* Anti-inflammatory drugs
• •No other concurrent investigational agents
• •No concurrent warfarin or other blood thinners
• •Female patient