RATIONALE: Interferon alfa may interfere with the growth of the cancer cells and slow the growth of kidney cancer. Isotretinoin may help kidney cancer cells develop into normal cells. It is not yet known whether interferon alfa plus isotretinoin is more effective than interferon alfa alone for kidney cancer.

PURPOSE: Randomized phase III trial to compare the effectiveness of interferon alfa with or without isotretinoin in treating patients who have metastatic kidney cancer.

OBJECTIVES: I. Assess the response rate and response duration of interferon alfa with vs without isotretinoin in patients with bidimensionally measurable progressive metastases from renal cell cancer. II. Assess the toxic effects of these regimens in this patients population. III. Determine the overall survival of this patient population treated with these regimens.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to participating center. Patients are randomized to one of two treatment arms. Arm I: Patients receive interferon alfa subcutaneously daily. Arm II: Patients receive interferon alfa as in arm I plus oral isotretinoin daily. Treatment continues for up to 1 year in the absence of disease progression or unacceptable toxicity. Patients are followed until death.

PROJECTED ACCRUAL: A total of 296 patients will be accrued for this study.

• Biological: recombinant interferon alfa
• Drug: chemotherapy
• Drug: isotretinoin

DISEASE CHARACTERISTICS: Histologically confirmed metastatic renal cell adenocarcinoma Histologic confirmation of metastases desirable Progression of metastases within 2 months of study No clinically manifest CNS metastasis Bidimensionally measurable metastases, as follows: Lung lesion with diameter greater than 2 cm Superficial lymph node or skin or subcutaneous lesion with diameter greater than 2.5 cm Lymph node in the mediastinum or retroperitoneal region, liver lesion, or soft tissue lesion visible on CT or ultrasound with initial diameter greater than 2.5 cm No bone lesion without surrounding, measurable soft tissue lesion

PATIENT CHARACTERISTICS: Age: 18 to 75 Performance status: WHO 0 or 1 Life expectancy: At least 90 days Hematopoietic: WBC greater than 3,000/mm3 OR Absolute granulocyte count greater than 1,500/mm3 OR Platelet count greater than 100,000/mm3 Hepatic: Bilirubin no greater than 1.1 mg/dL Lipids no greater than 1.5 times normal Renal: Creatinine no greater than 1.6 mg/dL Cardiovascular: No congestive heart failure No significant arrhythmia No complete bundle branch block Pulmonary: No serious concurrent pulmonary illness Other: No recent uncontrolled bleeding No serous effusion No history of autoimmune disease No controlled or uncontrolled active infection No seizure disorder or compromised CNS function No secondary gastrointestinal dysfunction that could interfere with drug absorption No psychological condition that would preclude participation or consent No second malignancy except basal cell skin cancer or carcinoma in situ of the cervix Not pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior immunotherapy Chemotherapy: No prior chemotherapy Endocrine therapy: No concurrent hormonal therapy Radiotherapy: At least 3 months since irradiation of target lesions Subsequent progression or new lesion required No concurrent radiotherapy Surgery: Prior nephrectomy required No concurrent surgery Other: No concurrent tetracyclines or hepatotoxic drugs