RATIONALE: Chemoprevention is the use of certain drugs to keep cancer from forming, growing, or coming back. The use of IH636 grape seed extract may prevent breast cancer. PURPOSE: This phase I trial is studying the side effects and best dose of IH636 grape seed extract in preventing breast cancer in postmenopausal women at risk of developing breast cancer.

OBJECTIVES: * Determine the efficacy of IH636 grape seed proanthocyanidin extract, in terms of suppression of estrogen biosynthesis, in healthy post-menopausal women at high risk of developing breast cancer. * Determine the safety and tolerability of this dietary supplement, in terms of symptoms and changes in markers of bone and lipid metabolism and in markers of nonspecific adrenal suppression, in these participants. * Determine, preliminarily, an optimum biologic dose of this dietary supplement, as defined by suppression of serum estradiol, in these participants. * Determine a minimum duration of use of this dietary supplement to achieve aromatase inhibition in these participants. OUTLINE: This is a pilot, dose-finding, placebo-controlled study. Participants receive oral placebo once or twice daily on days -14 to 0. Participants then receive oral IH636 grape seed proanthocyanidin extract once or twice daily on days 1-85. Treatment continues in the absence of toxicity. Cohorts of 6 participants receive one of four dose levels of IH636 grape seed proanthocyanidin extract up to an established safe dose. PROJECTED ACCRUAL: A total of 24 participants will be accrued for this study within 12 months.