Inclusion Criteria

DISEASE CHARACTERISTICS:

- Prior treatment on RTOG-9910 for intermediate relapse-risk stage II or III prostate
cancer as determined by any of the following combinations of factors:

- T1b-4, Gleason score 2-6, and prostate-specific antigen (PSA) greater than 10
ng/mL but no greater than 100 ng/mL

- T1b-4, Gleason score 7, and PSA less than 20 ng/mL

- T1b-1c, Gleason score 8-10, and PSA less than 20 ng/mL

- Radiotherapy completed within the past 6 months to 5 years

- Pretreatment (before enrollment on this study) erectile dysfunction as measured by
International Index of Erectile Function Question #1

- Erectile dysfunction before starting prostate cancer therapy allowed

- Patients without partners or without partners willing to participate allowed

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- Zubrod 0-2

Life expectancy

- Not specified

Hematopoietic

- Not specified

Hepatic

- Not specified

Renal

- Not specified

Cardiovascular

- No myocardial infarction within the past year

Other

- No other invasive cancer within the past 5 years except localized basal cell or
squamous cell skin cancer (stage 0-II)

- No anatomical genital abnormalities or concurrent conditions that would prohibit
sexual intercourse or preclude study participation

- No other major medical or psychiatric illness that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- Not specified

Endocrine therapy

- More than 6 months since prior androgen suppression (e.g., leuprolide or goserelin),
antiandrogen (e.g., bicalutamide, flutamide, or nilutamide), or estrogenic (e.g.,
diethylstibestrol) agents

Radiotherapy

- See Disease Characteristics

Surgery

- No prior penile implant

- No prior bilateral orchiectomy

Other

- No concurrent sildenafil

- No concurrent participation in another medical research study to treat prostate
cancer

- No concurrent organic nitrate or requirement for nitrates (e.g., nitroglycerin as
needed)

- No concurrent ketoconazole, itraconazole, or erythromycin

- No concurrent use of mechanical (vacuum) devices or intracorporeal, intraurethral,
topical, or oral agents for erectile dysfunction