According to the results of small Chinese epidemiologic study, soy intake reduces risk of both developing prostate cancer and reduces risk of prostate cancer metastasis. For this study, 100 men underwent a prostate biopsy to determine whether cancer was present. Results showed that among the 46 men determined to have cancer, median plasma genistein concentration was significantly lower than the median concentration in the men without prostate cancer. Furthermore, the age-adjusted odds ratio of prostate cancer risk comparing plasma genistein level above the median to below the median was 0.31 (95% CI 0.13-0.71). In addition, among the men whose cancer had metastasized the median plasma genistein concentration was significantly lower that it was in men whose cancer had not metastasized. This latter finding is supportive of clinical data suggesting genistein has the potential to inhibit metastasis.
Wu Y, Zhang L, Na R, et al. Plasma genistein and risk of prostate cancer in Chinese population. Int Urol Nephrol. (2015).