OUTLINE: This is a randomized, multicenter study. Patients are stratified according to center and mode of surgery. Patients are randomized to one of two treatment arms. Arm I: Patients undergo complete resection of tumor on day 0. Patients then receive mitomycin intraperitoneally (IP) over 23 hours on day 1 and fluorouracil IP over 24 hours on days 2-5. Patients then receive one of three systemic chemotherapy regimens for 6 months: Regimen I: Patients receive leucovorin calcium IV over 2 hours and fluorouracil IV over 22 hours on days 1 and 2. Treatment repeats every 2 weeks. Regimen II: Patients receive fluorouracil IV continuously for 7 weeks. Treatment repeats every 8 weeks. Regimen III: Leucovorin calcium and fluorouracil are administered as per standard procedure. Arm II: Patients receive treatment as in arm I but without early intraperitoneal chemotherapy. Patients are followed every 3 months for 2 years.