A Phase II Study of Surgical Debulking With Peritonectomy and Biweekly Intraperitoneal 5FU With Systemic Oxaliplatin/5FU/Leucovorin in Patients With Pseudomyxoma Peritonei or Peritoneal Carcinomatosis

Eligibility Criteria: * Histological Diagnosis: Patients must have a histologically documented pseudomyxoma peritonei or peritoneal carcinomatosis from colorectal/appendiceal and small intestinal adenocarcinoma. * Patients may have prior chemotherapy. * Age: Patients must be greater than or equal to 18 years old. Because no dosing or toxicity data are currently available on the use of oxaliplatin in patients \<18 years of age, children are excluded from this study, but will be eligible for other pediatric Phase I single-agent trials, when available. * Performance Status: ECOG 0-2. * Life Expectancy: greater than 8 weeks. * Recovery from Intercurrent Illness: Patients must have recovered from uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris or cardiac arrhythmia. * Hematological Status: Patients must have adequate bone marrow function defined as an absolute neutrophil count greater than or equal to 1,500/mm3, platelet count greater than or equal to 100,000/mm3 and hemoglobin greater than or equal to 8 g/dl. * Hepatic Function: Total bilirubin must be less than or equal to institutional upper limit of normal (ULN). Transaminases (SGOT and/or SGPT) may be up to 2.5 X ULN if alkaline phosphatase is less than or equal to ULN, or alkaline phosphatase may be up to 4 x ULN if transaminases are less than or equal to ULN. However, patients who have both transaminase elevation greater than 1.5 x ULN and alkaline phosphatase greater than 2.5 x ULN are not eligible for the study. * Renal Function: Patients must have adequate renal function defined as serum creatinine less than or equal to 2.0 mg/dl or creatinine clearance greater than or equal to 60 ml/min/1.73 m2 for patients with creatinine levels above 2.0 mg/dl. * Sexually Active Patients: For all sexually active patients, the use of adequate barrier contraception (hormonal or barrier method of birth control) will be required during therapy, prior to study entry and for the duration of study participation. Non-pregnant status will be determined in all women of childbearing potential. Pregnant and nursing women patients are not eligible. * HIV-Positive Patients: Patients receiving anti-retroviral therapy (HAART) for HIV infection are excluded from the study because of possible pharmacokinetic interactions. Appropriate studies will be undertaken in patients receiving HAART therapy, when indicated. * Informed Consent: After being informed of the treatment involved, patients must give written consent. The patient should not have any serious medical or psychiatric illness that would prevent either the giving of informed consent or the receipt of treatment. * Inclusion of Women and Minorities: Entry to this study is open to both men and women and to all racial and ethnic subgroups.