• Effect on the clinical incidence of cancer [ Designated as safety issue: No ]
  
• Effect on cancer-free survival, overall survival and serious cardiovascular events [ Designated as safety issue: No ]
  
• Quality of life [ Designated as safety issue: No ]
  
• Association of biological molecular markers with cancer risk [ Designated as safety issue: No ]
  
• Relationship between effects on cancer risk and genetic factors [ Designated as safety issue: No ]
  
• Effects in terms of intake of other nutrients, foods, and dietary supplements [ Designated as safety issue: No ]
  
• Effect of other dietary nutrients and dietary patterns on cancer risk [ Designated as safety issue: No ]
  
• Effects on the reduction of Alzheimer's disease incidence [ Designated as safety issue: No ]
  
• Reduction in the risk of age-related macular degeneration or cataract [ Designated as safety issue: No ]
  

OBJECTIVES:

• Compare the effect of selenium and vitamin E administered alone vs in combination on the clinical incidence of prostate cancer.
• Compare the effect of these prevention regimens on the incidence of lung cancer, colorectal cancer, and all cancers combined in participants on this study.
• Compare the effect of these prevention regimens on prostate cancer-free survival, lung cancer-free survival, colorectal cancer-free survival, cancer-free survival, overall survival, and serious cardiovascular events in these participants.
• Compare the quality of life of participants treated with these regimens.
• Determine the association of biological molecular markers with the risk of prostate cancer, lung cancer, and colon cancer in these participants.
• Determine the relationship between the effects of these regimens on prostate cancer risk and genetic factors in these participants.
• Determine whether the effects of these regimens on prostate cancer risk are conditional upon pre-study use of these supplements by these participants.
• Determine whether the effects of these regimens are conditional upon intake of other nutrients, foods, and dietary supplements by these participants.
• Determine the effect of other dietary nutrients and dietary patterns on prostate cancer risk in these participants.
• Determine the effects of these regimens on the reduction of Alzheimer's disease incidence in these participants.
• Determine whether these regimens reduce the risk of age-related macular degeneration or cataract in these participants.

OUTLINE: This is a randomized, double-blind, multicenter study. Participants are randomized to one of four prevention arms.

• Arm I: Participants receive 2 different oral placebos once daily.
• Arm II: Participants receive oral selenium and oral placebo once daily.
• Arm III: Participants receive oral vitamin E and oral placebo once daily.
• Arm IV: Participants receive oral selenium and oral vitamin E once daily. Treatment continues for 7-12 years in the absence of unacceptable toxicity or diagnosis of prostate cancer.

Quality of life is assessed at baseline and then at 1, 3, 5, and 7 years.

Participants are followed annually.

PROJECTED ACCRUAL: A total of 32,400 participants (8,100 per prevention arm) will be accrued for this study within 5 years.

DISEASE CHARACTERISTICS:

• Healthy male volunteers

• Digital rectal examination (DRE) deemed not suspicious for prostate cancer performed within 364 days prior to study entry

  • Participants with a suspicious DRE are ineligible even if a recent or subsequent biopsy is negative for cancer
• Total prostate-specific antigen ≤ 4.0 ng/mL within 364 days prior to study entry
• No prior prostate cancer or high-grade (grade 2-3) prostatic intraepithelial neoplasia

PATIENT CHARACTERISTICS:

Age:

• See Disease Characteristics

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Not specified

Renal:

• Not specified

Cardiovascular:

• Systolic blood pressure < 160 mm Hg
• Diastolic blood pressure < 90 mm Hg
• No history of hemorrhagic stroke

Other:

• No malignancies within the past 5 years except basal cell or squamous cell skin cancer
• No uncontrolled medical illness
• No retinitis pigmentosa

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• Not specified

Endocrine therapy

• Not specified

Radiotherapy

• Not specified

Surgery

• Not specified

Other

• At least 7 years since prior randomization to SWOG-9217, with completion of end-of-study biopsy requirement
• No additional concurrent selenium or vitamin E (contained in individual supplements, antioxidant mix, or multivitamin)
• Concurrent multivitamins allowed (supplied on study)
• No concurrent anticoagulation therapy (e.g., warfarin)

• Concurrent prophylactic aspirin (average daily dose no greater than 175 mg/day) allowed

  • Concurrent daily aspirin dose ≤ 81 mg for participants receiving clopidrogel
• Concurrent anti-hypertension medication allowed
• No concurrent participation in another study involving a medical, surgical, nutritional, or life-style intervention (unless no longer receiving the intervention and are in the follow-up phase only)