Interleukin-2, Interferon Alfa, and Fluorouracil Compared With Observation in Treating Patients Who Have Undergone Surgery for Kidney Cancer

RATIONALE: Interferon alfa may interfere with the growth of tumor cells. Interleukin-2 may stimulate a person's white blood cells to kill tumor cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining interferon alfa and interleukin-2 with fluorouracil may kill any remaining tumor cells following surgery. It is not yet known whether combining interferon alfa and interleukin-2 with fluorouracil is more effective than observation after surgery for kidney cancer. PURPOSE: Randomized phase III trial to compare the effectiveness of combining interleukin-2, interferon alfa, and fluorouracil to that of observation alone in treating patients who have undergone surgery for kidney cancer and are at high risk of relapse.