PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics At least 1 month but no longer than 8 months since prior immunotherapy Chemotherapy: Not specified Endocrine therapy: At least 1 week since prior systemic corticosteroids for symptomatic treatment of renal cell carcinoma At least 28 days since prior medroxyprogesterone acetate No concurrent medroxyprogesterone acetate Concurrent corticosteroids for symptomatic treatment of neurological complications caused by renal cancer allowed Radiotherapy: Concurrent radiotherapy to symptomatic lesions for symptom relief allowed Surgery: See Disease Characteristics Concurrent surgical removal of symptomatic lesions for symptom relief allowed Other: At least 28 days since other prior experimental therapeutic agents At least 28 days since other prior shark cartilage products No other concurrent therapies for metastatic renal cell carcinoma No other concurrent shark cartilage products