Table 1.
Clinical Trials of Soy chemoprevention of PCa.
| Reference | Design | Participants | Soy or isoflavone intake in the intervention group | Duration of trial | Main outcomes | Results |
|---|---|---|---|---|---|---|
| Bosland et al, 2013 [14] | Randomized, double-blind trial | 177 men with localized prostate cancer after radical prostatectomy ((intervention (n=87) and placebo (n=90)) | Daily consumption of 20g soy protein isolate | 2 years | Serum PSA | Null |
| Lazarevic et al, 2011 [20] | Randomized, double-blind trial | 54 men with localized prostate cancer prior to prostatectomy ((intervention (n = 23) and placebo (n = 24)) | Daily consumption of 30 mg synthetic genistein | 3–6 weeks | Tissue and serum PSA | Genistein reduced serum PSA levels in patients with localized PCa |
| Napora et al, 2011 [15] | Randomized, double-blind trial | 33 men undergoing androgen ablation therapy for PCa ((intervention (n=17) and placebo (n=16)) | Daily consumption of 20 g of soy protein containing 160 mg of total isoflavones | 12 weeks | Metabolic and inflammatory parameters | Null |
| deVere White et al, 2010 [12] | Randomized, double-blind trial from 0–6 months and open-label study from 6–12 months | 53 men with localized prostate cancer ((intervention (n = 23) and placebo (n = 24)) | Daily consumption of 450 mg genistein, 300 mg daidzein, and other isoflavones | 6 months | Serum PSA | Null |
| Kwan et al, 2010 [17] | Phase II trial | 29 PCa patients with biochemical failure after radiotherapy | Daily consumption of 50–100 mg of isoflavones | 6 months | PSA doubling times | Soy induced significant prolongation of PSA doubling time in 41% of PCa patients |
| Swami et al, 2009 [23] | Randomized, double-blind trial | 25 men with localized prostate cancer ((intervention (n = 13) and placebo (n = 12)) | Daily consumption of 81.6 isoflavone aglycones | 2 weeks | Prostaglandin synthesis | Soy isoflavones significantly reduced prostate COX-2 mRNA and increased p21 mRNA in PCa patients |
| Pendleton et al, 2008 [18] | Open-labeled, Phase II, nonrandomized trial | 20 patients with biochemical failure after prior local therapy | Daily consumption of 47 mg of isoflavonoid | 12 months | Serum PSA | Soy isoflavones decreased the slope of PSA in PCa patients. |
| Grainger et al, 2008 [19] | Open-labeled randomized trial | 21 patients with biochemical failure after prior local therapy | Daily consumption of 40 g of soy protein contain 80 mg of isoflavones | 4 weeks | Serum PSA and VEGF | Soy protein prolonged PSA doubling time and reduced VEGF in PCa patients |
| Hamilton-Reeves et al, 2008 [10] | Randomized trial | 58 men at high risk of prostate cancer ((HGPIN (n=40) or atypical small acinar proliferation (n=13)) or low grade prostate cancer (n=5) | Daily consumption of 40 g protein of soy protein (107 mg isoflavones) | 6 months | Anti-apoptotic (BAX) and proliferative (PCNA) tumor markers and serum PSA | Soy isoflavones decreased anti-apoptotic tumor markers and reduced the incidence of developing Pca with no significant effect on serum PSA levels |
| Hamilton-Reeves et al, 2007 [24] | same as Hamilton-Reeves et al, 2008 | same as Hamilton-Reeves et al, 2008 | same as Hamilton-Reeves et al, 2008 | same as Hamilton-Reeves et al, 2008 | Tumor AR and ER-β | Soy isoflavones suppressed tumor AR expression with no significant effect on ER-β expression |
| Maskarinec et al, 2006 [7] | Randomized double-blind crossover clinical trial | 23 healthy men | Daily consumption of 35–38 mg soy isoflavones | 3 months | Serum PSA | Insignificant reduction in PSA in 14% |
| Dalais et al, 2004 [21] | Randomized, double-blind trial | 29 men diagnosed with localized prostate cancer prior to radical prostatectomy | Daily consumption of 117mg soy isoflavones | NA | Serum PSA | Soy isoflavones reduced total PSA in PCa patients |
| Kumar et al, 2004 [13] | Randomized, double-blind trial | 59 men with localized prostate cancer ((intervention (n = 29) and placebo (n = 30)) | Daily consumption of 60 mg soy isoflavones | 12 weeks | Serum PSA | Insignificant reduction in total and free PSA in the intervention arm relative to the placebo arm |
| deVere White et al, 2004 [16] | open-label pilot study | 52 patients with biochemical failure after prior therapy | Daily consumption of 450 mg genistein and 450 mg aglycone isoflavones | 6 months | Serum PSA | Null |
| Adams et al, 2004 [8] | Randomized, double-blind trial | 81 healthy men ((intervention (n = 34) and control (n = 47)) | Daily consumption of 83 mg soy isoflavones | 12 months | Serum PSA | Null |
| Jenkins et al, 2003 [9] | Randomized double-blind crossover clinical trial | 46 healthy middle-aged men | Daily consumption of 116 mg isoflavones | 3–4 weeks | Serum PSA | Null |
| Hussain et al, 2003 [22] | open-label pilot study | 39 patients with Pca under watchful waiting with rising PSA (group I) or had increasing serum PSA following local therapy (group II) or while receiving hormone therapy (group III). | Daily consumption of 200 mg soy isoflavones | 3–6 months | Serum PSA | Soy isoflavones decreased the rate of the rise of serum PSA |
| Urban et al, 2001 [11] | Randomized double-blind crossover clinical trial | 34 men with elevated PSA more than 4ng/ml | Daily consumption of 40 gm of isolated soy protein contain 42 mg genistein and 27 mg daidzein | 6 weeks | Serum PSA | Null |