Fulvestrant in Treating Patients With Advanced Prostate Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed adenocarcinoma of the prostate * Advanced disease * Must have androgen-independent prostate cancer meeting the following criteria: * Evidence of rising prostate-specific antigen (PSA) level and absolute value ≥ 5 ng/mL based on 2 measurements taken ≥ 2 weeks apart (measurements must be done after androgen deprivation \[orchiectomy or luteinizing hormone-release hormone (LHRH) analogue\] and antiandrogen withdrawal) * Rising PSA required for ≥ 28 days after antiandrogen or progestational therapy for prostate cancer (≥ 42 days after bicalutamide or nilutamide) * Testosterone \< 50 ng/mL (unless surgically castrated) * Measurable or evaluable disease * PSA elevation constitutes evaluable disease PATIENT CHARACTERISTICS: Performance status * ECOG 0-2 Life expectancy * Not specified Hematopoietic * WBC \> 3,000/mm\^3 * Neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 8 g/dL (transfusion or epoetin alfa allowed) * No bleeding diathesis (e.g., disseminated intravascular coagulation or clotting factor deficiency) Hepatic * Bilirubin normal * Gilbert's disease with bilirubin ≤ 3 times upper limit of normal (ULN) allowed in the absence of other etiology (e.g., hemolysis-reticulocyte count \< 5%) and liver function tests normal * SGOT and/or SGPT ≤ 2 times ULN * INR \< 1.6 Renal * Creatinine \< 2.5 mg/dL Cardiovascular * No unstable cardiac disease requiring medication * No new onset crescendo or rest angina * Stable exertional angina allowed Other * Fertile patients must use effective barrier contraception during and for 3 months after completion of study treatment * No other active malignancy within the past 2 years except nonmelanoma skin cancer or superficial bladder cancer * No history of significant neurologic or psychiatric disorders, including psychotic disorders, dementia, or seizures * No other serious illness or medical condition * No active infection * No known hypersensitivity to active or inactive excipients of fulvestrant (e.g., castor oil or mannitol) PRIOR CONCURRENT THERAPY: Biologic therapy * Prior retinoids, vaccines, and cytokines are not considered cytotoxic and are allowed Chemotherapy * No more than 1 prior cytotoxic chemotherapy regimen * More than 3 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) * No concurrent chemotherapy Endocrine therapy * See Disease Characteristics * Prior glucocorticoids, antiandrogens, progestational agents, estrogens, and LHRH analogues are not considered cytotoxic and are allowed * At least 4 weeks since prior flutamide (6 weeks for bicalutamide or nilutamide) * Concurrent megestrol acetate allowed at a stable dose of ≤ 40 mg/day * Concurrent androgen deprivation using LHRH analogues allowed but must continue during study treatment or orchiectomy is required to maintain castrate levels of testosterone Radiotherapy * More than 3 weeks since prior radiotherapy * No concurrent radiotherapy Surgery * See Disease Characteristics * See Endocrine therapy Other * Recovered from all prior therapy * Prior cholecalciferol analogues, ketoconazole, aminoglutethimide, peroxisome-proliferation-activated receptor-gamma agonists or antagonists, or PC-SPES are not considered cytotoxic and are allowed * No prior long-term anticoagulation therapy (antiplatelet therapy allowed) * More than 4 weeks since prior investigational drugs * No other concurrent anticancer therapy (e.g., PC-SPES) * No concurrent bisphosphonates unless receiving a stable dose at study entry * No concurrent therapy that may alter androgen metabolism or androgen levels * No concurrent full anticoagulation