ZD 1839 in Treating Patients With Prostate Cancer That Has Not Responded to Hormone Therapy

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed adenocarcinoma of the prostate PSA at least 20 ng/mL at study entry Must have documented evidence of disease progression, defined by 1 of the following conditions: Rising PSA documented after discontinuation of peripheral antiandrogens Minimum evidence of progression is a 25% increase in PSA over the reference value, provided that the increase is at least 5 ng/mL Must have a first increase in PSA documented at least 1 week after the reference value and a second increase in PSA documented at least 1 week after the first increase Progressive measurable disease during androgen ablative therapy (including medical or surgical castration) Castrate level (no greater than 50 ng/mL) of testosterone required if receiving medical androgen-ablative therapy at study entry Concurrent luteinizing hormone-releasing hormone agonist therapy required if receiving this medication at study entry PATIENT CHARACTERISTICS: Age: 16 and over Performance status: ECOG 0-1 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 2 times upper limit of normal (ULN) AST/ALT no greater than 2.5 times ULN (5 times ULN if documented liver metastases) Renal: Creatinine no greater than 2 times ULN Other: No other malignancy within the past 5 years No active uncontrolled bacterial, fungal, or viral infection No significant neurological disorder that would preclude informed consent No other serious illness or medical condition that would preclude study PRIOR CONCURRENT THERAPY: Biologic therapy: Concurrent epoetin alfa allowed Chemotherapy: No prior chemotherapy No concurrent cytotoxic therapy Endocrine therapy: See Disease Characteristics At least 4 weeks since prior peripheral antiandrogens (6 weeks for bicalutamide) Concurrent steroids allowed if on stable dose for at least 4 weeks before study and no dose increase planned Radiotherapy: At least 4 weeks since prior radiotherapy except low-dose, nonmyelosuppressive radiotherapy approved by the National Cancer Institute of Canada, Clinical Trials Group Surgery: See Disease Characteristics No concurrent ophthalmic surgery Other: No prior investigational agents No other concurrent investigational therapy No concurrent ketoconazole No concurrent high-dose narcotic therapy for pain (e.g., morphine equivalent dose more than 60 mg/day) Concurrent bisphosphonates allowed