Randomized Placebo-Controlled Adjuvant Study of Prevention of Prostate Cancer Recurrence After Radical Prostatectomy by Soy Protein Isolate
Trial Snapshot
- Phase
- Phase 2
- Status
- Completed
- Enrollment
- 284
- Locations
- 1
- Primary Endpoint
- Two-year PSA failure rate (as surrogate for recurrence)
Study Overview
Brief Summary
RATIONALE: Soy protein may help prevent prostate cancer recurrence in patients who have undergone surgery for prostate cancer.
PURPOSE: This randomized phase II/III trial is studying how well soy protein works and compares it to a placebo in preventing recurrent cancer in patients who have undergone surgery for stage II prostate cancer.
Detailed Description
OBJECTIVES:
- 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 treatment arms.
- 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 toxicity.
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.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Primary Purpose
- Treatment
- Masking
- Double
Eligibility Criteria
- Ages
- 40 Years to 75 Years (Adult, Older Adult)
- Sex
- Male
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •DISEASE CHARACTERISTICS:
- •Diagnosis of prostate cancer
- •Clinically localized (T1c or T2) disease
- •At high risk for recurrence, as defined by ≥ 1 of the following:
- •Preoperative PSA > 20.0 ng/mL
- •Seminal vesicle invasion
- •Extracapsular extension (excluding the bladder neck)
- •Positive surgical margins (excluding apical margins)
- •Micrometastases in any removed pelvic lymph nodes
- •Final Gleason score of ≥ 8
- •Must have undergone radical prostatectomy for prostate cancer within the past 4 months
- •Must have an undetectable PSA (< 0.07 ng/mL) at baseline, as measured by Tosoh PSA assay
- •No clinical evidence of locally recurrent or metastatic disease
- •PATIENT CHARACTERISTICS:
- •No significant intake of soy (i.e., more than once a week) at baseline including, but not limited to, any of the following:
- •Vegetarians who regularly consume soy products (e.g., tofu)
- •Individuals with customary Asian dietary habits, including regular intake of soy products
- •Individuals who use soy-based milk replacements
- •No anemia, iron deficiency problems, or subclinical iron deficiency at baseline
- •No diabetes
- •No thyroid disease
- •No requirement for a sodium-free diet
- •No substantive tendency to be constipated (i.e., ≥ grade 2 constipation experienced regularly)
- •No medical problem that would preclude the consumption of the soy containing beverage powder, including allergies against soy (or milk protein)
- •No concurrent major disease, including major mental disease or major substance abuse problems
- •No significant side effects from medication
- •PRIOR CONCURRENT THERAPY:
- •See Disease Characteristics
- •No concurrent radiotherapy or hormonal therapy
- •No other concurrent adjuvant therapy for prostate cancer
Exclusion Criteria
- Not provided
Arms & Interventions
Arm I
Patients receive an oral soy protein isolate beverage once daily.
Intervention: soy protein isolate (Dietary Supplement)
Arm II
Patients receive an oral casein placebo beverage once daily.
Intervention: placebo (Other)
Outcomes
Primary Outcomes
Two-year PSA failure rate (as surrogate for recurrence)
Time to PSA failure
Secondary Outcomes
- Serum total cholesterol levels
- Apoptotic activity as measured by serum soluble Fas and Fas-ligand levels
- Oxidative stress as measured by serum 8-isoprostane levels
- Equol production as measured by serum equol concentration
- Angiogenesis as measured by serum VEGF and bFGF levels
- Steroid hormone axis as measured by serum testosterone, estradiol, and SHBG levels
- Thyroid activity as measured by serum T3 and T4 levels
- Isoflavone uptake or compliance as measured by serum isoflavone concentration
- IGF axis as measured by serum IGF-1 and IGFBP-3 levels