Objective: To determine prognostic factors and the impact of intraperitoneal (IP) treatment after surgical resection of peritoneal mucinous carcinomatosis (PMC) of appendiceal origin.
Summary of background data: PMC is a rare, malignant, intra-abdominal neoplasm that produces large amounts of mucin. Patients typically present with diffuse peritoneal disease. After surgical treatment, multiple locoregional recurrences are common; recurrences outside the abdomen are infrequent. Treatment regimens include debulking, radiotherapy with IP radioisotopes, and chemotherapies (IP, systemic, or both). Because reported data are variable and heterogeneous, treatment evaluations are challenging.
Methods: We retrospectively reviewed 115 consecutive patients with PMC who underwent maximal surgical resection with or without postoperative therapy between 1985 and 2000 at Mayo Clinic Rochester. After maximal resection, 37 patients received IP 5-fluorouracil, 35 of whom also received IP chromic phosphate P 32. The Kaplan-Meier method was used to estimate overall survival (OS) and disease-free survival.
Results: All gross disease was removed in 61% of patients. With a median follow-up of 6.1 years, the median OS was 8.1 years. Median OS for patients receiving versus not receiving IP therapy was 23.5 years versus 7.5 years, respectively. The 5-, 10-, and 15-year OS for those receiving and not receiving IP therapy was 82%, 65%, and 52% versus 60%, 27%, and 15%, respectively. Adverse prognostic factors for OS identified by univariate analysis included partial mucin debulking, adenocarcinoma histology, systemic chemotherapy, diffuse IP disease at presentation, and no IP therapy. On multivariate analysis, diffuse IP disease at presentation and no IP therapy remained significant. A separate analysis was performed for the 70 patients who underwent gross total resection, 51% of whom received IP therapy. Adverse prognostic factors for OS included adenocarcinoma histology, systemic chemotherapy, and no IP therapy.
Conclusions: This large, single-institution, retrospective series with long-term follow-up suggests that IP chromic phosphate P 32 and 5-fluorouracil after maximal surgical resection of PMC of appendiceal origin is associated with improved OS and disease-free survival.