Soy Protein in Preventing Recurrent Cancer in Patients Who Have Undergone Surgery for Stage II Prostate Cancer

Study Overview
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Brief Summary
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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
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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.

Official Title
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Randomized Placebo-Controlled Adjuvant Study of Prevention of Prostate Cancer Recurrence After Radical Prostatectomy by Soy Protein Isolate

Conditions
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Prostate Cancer

Intervention / Treatment
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* Dietary Supplement: soy protein isolate
* Other: placebo


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arm I<br>Patients receive an oral soy protein isolate beverage once daily. | Dietary Supplement: soy protein isolate<br>* Given orally<br>|
| Placebo Comparator: Arm II<br>Patients receive an oral casein placebo beverage once daily. | Other: placebo<br>* Given orally<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Two-year PSA failure rate (as surrogate for recurrence) |  |  | 
| Time to PSA failure |  |  | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Isoflavone uptake or compliance as measured by serum isoflavone concentration |  |  | 
| Serum total cholesterol levels |  |  | 
| Steroid hormone axis as measured by serum testosterone, estradiol, and SHBG levels |  |  | 
| Thyroid activity as measured by serum T3 and T4 levels |  |  | 
| Apoptotic activity as measured by serum soluble Fas and Fas-ligand levels |  |  | 
| Angiogenesis as measured by serum VEGF and bFGF levels |  |  | 
| Oxidative stress as measured by serum 8-isoprostane levels |  |  | 
| IGF axis as measured by serum IGF-1 and IGFBP-3 levels |  |  | 
| Equol production as measured by serum equol concentration |  |  | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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stage IIB prostate cancer, stage IIA prostate cancer