Fluorouracil and Biological Therapy in Treating Patients With Metastatic Kidney or Colorectal Cancer

RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Biological therapies use different ways to stimulate the immune system and stop cancer cells from growing. Combining chemotherapy with biological therapy may kill more tumor cells.
PURPOSE: Phase I trial to study the effectiveness of fluorouracil combined with biological therapy in treating patients who have metastatic kidney or colorectal cancer.