This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall goal of this proposal is to investigate the effect of sy protein on cognition, quality of life and hot flashes in men with prostate cancer who are currently undergoing medical castration or have undergone surgical castration. Historically, radical prostatectomy and/or radiation therapy has been the mainstay of treatment in patients with locally confined PCa. However, for patients with metastatic PCa or those with a recurrence (detected by a rising PSA), androgen deprivation therapy (ADT) is frequently employed. The most common mode of ADT is the use of GnRH agonists which result in central hypogonadism (orchiectomy is performed in minority). Several complications of hypotestosteronemia have been described in men with hypogonadism. These include decline in lean body mass (LBM), muscle strength, osteoporosis, decrease in quality of life (QOL) and sexual dysfunction. Another complication of hypogonadism is hot flashes. This complication is seen with the highest frequency in men with PCa undergoing ADT (80-90% of the patients). Studies of postmenopausal women indicate that performance on tasks of memory improves following estrogen replacement therapy. Due to the potential risks involved with estrogen therapy, focus is being shifted to plant estrogens (isoflavones). Studying men with PCa proves the best model to evaluate the effects of isoflavones on cognition in men, while providing needed improvement in QOL. Furthermore, it may also result in an improvement in hot flashes.