Insulin-Like Growth Factors One study showed that serum levels of insulin-like growth factor (IGF)-1 and IGF-binding protein (IGFBP-3) and the IGF-1/IGFBP-3 ratio were significantly lower after treatment with polyphenon E, which contained 800 mg of EGCG and lesser amounts of EC, EGC, and ECG (a total of 1 1.3 g of tea polyphenols) [84]. Therefore, in this review, we present current knowledge regarding the anti-cancer effects of green tea extracts in the prevention and treatment of prostate malignancy, with a particular focus on the molecular mechanisms of action, such as influencing tumor growth, apoptosis, androgen receptor signaling, cell cycle, and various malignant behaviors. Finally, the future direction for the use of green tea extracts as treatment strategies in patients with prostate malignancy is launched. (Theaceae family), has been widely consumed as a beverage in Asian countries such as China, Japan, Korea, and India for centuries [4,9,10,11,12]. Green tea catechins (GTCs) are a type of green tea polyphenols (GTP) that are present at high levels in green tea, and they are the source of its unique bitter taste. GTCs present in green tea include (?)-epigallocatechin-3-gallate (EGCG); (?)-epicatechin (EC); (?)-epigallocatechin (EGC); and (?)-epicatechin-3-gallate (ECG) [13]. Among these GTCs, in vitro and animal studies have shown that EGCG is usually highly bioactive and targets the molecular pathways implicated in prostate carcinogenesis [7,11,12,14,15]. In general, the growth of hormone-na?ve Fluorocurarine chloride PC cells is usually strongly suppressed by androgen deprivation. In addition, the prognosis of patients with organ-confined PC is usually good with radical prostatectomy and radiotherapy. Therefore, in these patients, there is little need for treatments involving the use of green tea or GTPs. Hormonal therapy, including androgen deprivation therapy, is recognized as the standard for these patients even in the case of advanced or metastatic disease. However, regrettably, most patients develop castration-resistant prostate malignancy (CRPC) despite therapeutic suppression of testosterone levels. In addition, the prognosis of CRPC patients is poor owing to the high malignant potential Fluorocurarine chloride and aggressiveness of CRPC. CRPC is considered to involve numerous gene mutations and alternate signaling pathways. Therefore, Fluorocurarine chloride treatment strategies targeting a few pathways are not effective, leading to the rapid development of chemoresistance. Thus, the development of new treatment strategies is essential to improve the prognosis of CRPC patients. PC has a long latency period and is typically diagnosed in elderly men. Therefore, chemoprevention strategies have been studied in detail by many investigators [16,17]. Conversely, security and cost are important since long-term periodic administration is necessary for the chemoprevention of PC. In addition, an JAM3 ideal agent for the chemoprevention of PC would also prevent other diseases and promote the maintenance of healthy Fluorocurarine chloride conditions. Thus, natural compounds, including green tea, rather than chemical agents, are the major subjects of in vivo, in vitro, and epidemiological studies around the chemoprevention of PC [18]. In this review, we paid special attention to three aspects of the effects of green tea on PC: the chemopreventive effect against PC, therapeutic effects for treating PC, and the molecular mechanisms of such anti-cancer effects. Several prospective trials are investigating the chemoprevention of PC by green tea. Further, basic research is being conducted with regard to the therapeutic effect of green tea against PC. Recently, some studies have suggested the preoperative administration of green tea before radical prostatectomy. Therefore, desire for the therapeutic effects of green tea is usually increasing. However, the limitations of the anti-cancer effects and the clinical usefulness of green tea must also be understood to evaluate the prevention and treatment strategies by using green tea-based methods. Herein, we present data on green tea with respect to PC and believe that these data will be useful for future experts. 2. Anti-Cancer Effects of Green Tea 2.1. Case-Control Studies Several case-control studies have investigated the preventive effects of green tea for PC. For example, a case-control study with 140 PC cases and an equal number of hospital patients as controls was performed in Japan [19]. This study showed an inverse correlation between green tea consumption and PC risk, although it did not reach the level of significance [19]. Conversely, another case-control study in China showed that increasing the frequency, period, and quantity of green tea consumption could lead to a lower risk of PC [7]. In this study, a hospital-based 1:2 case-control design (130 cases and 274 hospital controls) was used to investigate the association between green tea consumption and PC. This was the first study providing comprehensive evidence of the protective effect of green tea against PC. The adjusted odds ratios (OR) compared with those of men who by no means or seldom drank green tea were 0.28 (95% CI: 0.17, 0.47) for those drinking tea, 0.12 (95% CI: 0.06, 0.26) for those drinking tea for over 40 years, and 0.27 (95% CI: 0.15, 0.48) for those drinking more than 3 cups (1 L) per day. These results suggest that green tea has a protective effect against PC. A second case-control study in China, which consisted of.