RATIONALE: Estrogen may cause the growth of prostate cancer cells. Hormone therapy using fulvestrant may fight prostate cancer by blocking the use of estrogen by the tumor cells.

PURPOSE: This phase II trial is studying how well fulvestrant works in treating patients with advanced prostate cancer.

OBJECTIVES:

Primary

• Determine if the prostate-specific antigen objective response (complete and partial response) rate is > 0.2 in patients with androgen-independent advanced prostate cancer treated with fulvestrant.

Secondary

• Determine the toxicity of this drug in these patients.

OUTLINE: This is an open-label study.

Patients receive fulvestrant intramuscularly on days 0, 14, and 28. Courses repeat once a month in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed periodically for survival.

PROJECTED ACCRUAL: A total of 33 patients will be accrued for this study.

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