Vitamin E, Selenium, and Soy Protein in Preventing Cancer in Patients With High-Grade Prostate Neoplasia

N

NCIC Clinical Trials Group

Status and phase

Completed
Phase 3

Conditions

Precancerous/Nonmalignant Condition
Prostate Cancer

Treatments

Dietary Supplement: soy protein isolate
Dietary Supplement: vitamin E
Dietary Supplement: selenium

Study type

Interventional

Funder types

NETWORK

Identifiers

NCT00064194
CAN-NCIC-PRP1 (Other Identifier)
CDR0000310096 (Other Identifier)
PRP1

Details and patient eligibility

About

RATIONALE: Chemoprevention therapy is the use of certain substances to try to prevent the development or recurrence of cancer. Vitamin E, selenium, and soy protein may be effective in preventing the development of prostate cancer. PURPOSE: Randomized phase III trial to study the effectiveness of combining vitamin E, selenium, and soy protein in preventing prostate cancer in patients who have high-grade prostate neoplasia.

Full description

OBJECTIVES: Determine whether nutritional supplementation with soy protein isolate, vitamin E, and selenium can delay the time to development of invasive prostate cancer (disease-free survival) in patients with high-grade prostatic intraepithelial neoplasia. Determine the effect of this supplementation on intermediate endpoints that may reflect a lessened risk of invasive prostate cancer (e.g., serum PSA levels, hormone levels, lycopene, malondialdehyde, vitamin E, and reduced thiol groups) in these patients. Determine the safety of this supplementation in these patients. OUTLINE: This is a randomized, double-blind, multicenter study. Patients are stratified according to participating center. Patients are randomized to 1 of 2 treatment arms. Arm I: Patients receive oral vitamin E, oral selenium, and oral soy protein isolate twice daily. Arm II: Patients receive oral placebo twice daily. In both arms, treatment continues for 3 years in the absence of invasive prostate cancer (demonstrated on biopsy) or unacceptable toxicity. Patients are followed every 3 months for 1 year and then every 6 months for 2 years. PROJECTED ACCRUAL: A total of 306 patients (153 per treatment arm) will be accrued for this study within 6 years.

Enrollment

310 patients

Sex

Male

Ages

Under 120 years old

Volunteers

No Healthy Volunteers

Inclusion and exclusion criteria

DISEASE CHARACTERISTICS:

Histologically confirmed high-grade prostatic intraepithelial neoplasia (HGPIN)

  • No evidence of invasive prostate cancer by at least 2 biopsies within the past 18 months
  • At least 1 biopsy must show evidence of HGPIN within the past 6 months
  • No prior invasive prostate cancer

PATIENT CHARACTERISTICS:

Age

Not specified

Performance status

Not specified

Life expectancy

More than 5 years

Hematopoietic

  • Platelet count at least 75,000/mm^3
  • No coagulopathies

Hepatic

  • Bilirubin no greater than 2 times upper limit of normal (ULN)
  • PT (INR) no greater than 1.5 times ULN
  • PTT no greater than 1.5 times ULN
  • No hepatic insufficiencies

Renal

  • Creatinine no greater than 2 times ULN
  • No renal insufficiencies

Other

  • No prior nonmelanoma skin cancer (e.g., squamous cell or basal cell carcinoma)
  • No other malignancy within the past 5 years except superficial bladder cancer
  • No known bowel malabsorption
  • No dietary behavior (e.g., morbid obesity or eating disorders) that would limit adherence to study therapy
  • No major illness, including psychiatric illness, that would preclude study compliance and follow-up

PRIOR CONCURRENT THERAPY:

Biologic therapy

Not specified

Chemotherapy

Not specified

Endocrine therapy

  • More than 3 months since prior androgen therapy
  • More than 3 months since prior hormonal therapy for benign prostatic hyperplasia (e.g., finasteride)
  • No concurrent finasteride
  • No concurrent androgen therapy

Radiotherapy

More than 2 years since prior radiotherapy to the pelvic region

Surgery

Not specified

Other

  • More than 2 weeks since prior supplemental vitamin E or selenium
  • No other concurrent vitamin E (greater than 100 IU/day), selenium, or soy protein isolate (more than 2 servings/week)
  • No other concurrent treatment for high-grade prostatic intraepithelial neoplasia

Trial contacts and locations

3

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Data sourced from clinicaltrials.gov

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