Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed adenocarcinoma of the prostate

- Measurable or non-measurable disease

- Metastatic disease allowed

- Castrate levels of serum testosterone (either after orchiectomy or maintained on a
luteinizing hormone-releasing hormone agonist or antagonist)

- Prostate-specific antigen (PSA) greater than 10 ng/mL at baseline and rising, with 2
consecutive increases measured at least 1 week apart*

- No known brain metastases NOTE: *If the third PSA value has not risen above the
second PSA value, a fourth measurement must be obtained that is higher than the
second value

PATIENT CHARACTERISTICS:

Age

- Over 18

Performance status

- ECOG 0-1

Life expectancy

- More than 12 weeks

Hematopoietic

- Absolute neutrophil count greater than 1,500/mm^3

- WBC greater than 3,000/mm^3

- Platelet count greater than 100,000/mm^3

Hepatic

- AST and ALT no greater than 2.5 times upper limit of normal

- Bilirubin normal

Renal

- Creatinine normal OR

- Creatinine clearance greater than 60 mL/min

Cardiovascular

- No symptomatic congestive heart failure

- No unstable angina pectoris

- No cardiac arrhythmia

Other

- Able to tolerate oral medication

- Fertile patients must use effective contraception

- No prior allergic reaction to compounds of similar chemical or biological composition
to fenretinide

- No other concurrent uncontrolled illness

- No ongoing or active infection

- No psychiatric illness or social situation that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- No prior cytotoxic chemotherapy

Endocrine therapy

- See Disease Characteristics

- At least 6 weeks since prior antiandrogen therapy with any of the following:

- Cyproterone

- Flutamide

- Bicalutamide

- Nilutamide

- Concurrent corticosteroids allowed provided therapy was initiated before study entry

Radiotherapy

- At least 4 weeks since prior radiotherapy and recovered

- No concurrent radiotherapy, including for pain

- No concurrent radioisotopes (e.g., strontium chloride Sr 89 or samarium Sm 153
lexidronam pentasodium)

Other

- More than 4 weeks since prior investigational agents

- No concurrent antioxidants (e.g., ascorbic acid or vitamin E), vitamin A, or beta
carotene supplements

- No concurrent combination antiretroviral therapy for HIV-positive patients

- No other concurrent investigational or commercial anticancer agents or therapies