Randomized Placebo-Controlled Adjuvant Study of Prevention of Prostate Cancer Recurrence After Radical Prostatectomy by Soy Protein Isolate
- Determine whether soy protein isolate reduces the PSA failure rate and time to PSA
failure within 2 years following radical prostatectomy in patients who are at high risk
for prostate cancer recurrence.
- Determine the effects of soy protein isolate on intermediate biomarkers of steroid
hormone axis (testosterone, estradiol, and SHBG) and thyroid activity (T3 and T4).
- Determine the effects of soy protein isolate on intermediate biomarkers of apoptosis
(soluble Fas and Fas-ligand), angiogenesis (VEGF and bFGF), antioxidant activity
(8-isoprostanes), and IGF axis (IGF-1 and IGFBP-3).
- Compare patients who are equol producers to those who are non-producers.
OUTLINE: This is a multicenter study. Patients are stratified according to hospital/clinic
site (NYU vs UIC or Jesse Brown VA Medical Center vs other sites), number of high-risk
characteristics (1 vs > 1), and race (African American vs non-African American [i.e.,
non-Hispanic White, Hispanic, Asian, and other]). Patients are randomized to 1 of 2
- Arm I: Patients receive an oral soy protein isolate beverage once daily.
- Arm II: Patients receive an oral casein placebo beverage once daily. Treatment in both
arms continues for up to 2 years in the absence of disease progression or unacceptable
Blood samples are collected periodically for biomarker laboratory studies. Samples are
analyzed to measure PSA levels by Tosoh PSA assay; cholesterol levels; isoflavone and equol
concentrations by HPLC and ESA; and indicators of steroid hormone axis (testosterone,
estradiol, and SHBG), indicators of thyroid activity (T3 and T4), indicators of apoptosis
(soluble Fas and Fas-ligand), indicators of angiogenesis (VEGF and bFGF), indicators of
oxidative stress (8-isoprostanes), and indicators of IGF axis (IGF-1 and IGFBP-3) by ELISA.
Allocation: Randomized, Masking: Double-Blind, Primary Purpose: Treatment
Two-year PSA failure rate (as surrogate for recurrence)
Maarten C. Bosland, DVSc, PhD
University of Illinois
|University of Illinois Cancer Center||Chicago, Illinois 60612-7243|