OBJECTIVES: I. Evaluate the toxic effects, patient tolerance, and practicality of administering interferon alfa-2b, fluorouracil, interleukin-2, and isotretinoin (FUNIL-cRa) in patients with metastatic and/or recurrent renal cell carcinoma. II. Obtain a pilot indication of responsiveness of these patients to this regimen. III. Evaluate the measurement of tumor thymidylate synthetase as a prediction of response of these patients to this and other fluorouracil based regimens.