Technical Feasibility of Modified Early Post-Operative Intraperitoneal Chemotherapy (mEPIC)

Inclusion Criteria: * Patient's age 18 years or older, both genders. * In good general health as evidenced by an ECOG score of 0 or 1. * Histological diagnosis of appendicular or colorectal tumors with peritoneal carcinomatosis, either synchronous (\< 12 months after primary diagnosis) or metachronous (\>12 months after the primary diagnosis) * Complete staging defined as: (1)Computed tomography (CT) scan of the chest, abdomen and pelvis. (2) Positron emission tomography (PET) scan when clinically appropriate. (3) Diagnostic laparoscopy reporting Peritoneal carcinomatosis index (PCI) +/- biopsy * Meets criteria for recommendation by combined multidisciplinary team and tumor board for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS+HIPEC) followed by mEPIC * Surgery must be performed within 4-6 weeks following the end of neoadjuvant therapy or 4-6 weeks following the patient's enrollment if no neoadjuvant therapy needed. * Provision of signed and dated informed consent form * Stated willingness to comply with all study procedures and availability for the study duration * Hematology: Absolute neutrophil count (ANC) ≥ 1,500/ μL; Platelets \> 75,000/ μL. * Adequate Renal function Creatinine \<1.5 x the upper limit of normal (ULN) or calculated creatinine clearance of ≥ 50ml/min. * Adequate Hepatic function: Bilirubin less than 1.5mg/dL; (except in patients with Gilbert's Syndrome, who must have a total bilirubin less than 3.0mg/dL). Exclusion Criteria: Pre-cytoreductive surgery: * Other malignancies other than appendicular and colorectal neoplasms with peritoneal involvement * Inability to complete cytoreductive surgery (ECOG 2 or above) or any patient deemed unfit for surgery * Known allergic reaction or major toxicity to Fluorouracil * Contraindications to Fluorouracil, including history of coronary spasm and/or known dihydropyrimidine dehydrogenase deficiency * Pregnancy * Evidence of extensive intraperitoneal adhesions at the time of surgery which prohibits intraperitoneal therapy, as determined by the operating surgeon. * Any condition that would preclude the ability to deliver appropriate intraperitoneal (IP) therapy. Post-cytoreductive surgery: * Patient deemed not medically suitable to receive mEPIC protocol according to surgical team * Uncorrected coagulopathy and/or thrombocytopenia and/or neutropenia * Active infection * Hemodynamic and / or respiratory compromise * Evidence of extensive intraperitoneal adhesions at the time of surgery which prohibits intraperitoneal therapy, as determined by the operating surgeon. * Any condition that would preclude the ability to deliver appropriate IP therapy.