Soy Isoflavones in Treating Patients Who Are Undergoing Radical Prostatectomy for Stage I or Stage II Adenocarcinoma of the Prostate

RATIONALE: Chemoprevention therapy is the use of certain drugs to try to prevent or delay the development of early cancer. Soy isoflavones may be effective in delaying the development of early prostate cancer. PURPOSE: This randomized phase II trial is studying different regimens of soy isoflavones to compare how well they work in treating patients who are undergoing radical prostatectomy for stage I or stage II prostate cancer (adenocarcinoma).