Background: Pseudomyxoma peritonei (PMP) is a low-grade malignancy characterized by mucinous tumor on the peritoneal surface. Treatment involves cytoreductive surgery (CRS) to remove all macroscopic tumor and perioperative intraperitoneal chemotherapy (PIC) to eliminate remaining microscopic disease.
Patients and methods: Between 1994 and 2009, 93 patients were treated at the Norwegian Radium Hospital with complete CRS and PIC. PIC was administered as early postoperative intraperitoneal chemotherapy (EPIC) using mitomycin C (MMC) and 5-fluoruracil (n = 48) and as hyperthermic intraperitoneal chemotherapy (HIPEC) using MMC (n = 45). Patients were classified into three histopathological subgroups: Disseminated peritoneal adenomucinosis (n = 57), peritoneal mucinous carcinomatosis (n = 21) and an intermediate group (n = 15). Tumor distribution by peritoneal cancer index (PCI) was PCI ≤ 10 (n = 31), PCI 11-20 (n = 29), PCI ≥ 21 (n = 33).
Results: Recurrence was diagnosed in 38 patients and 25 patients died during follow-up. Estimated 10-year overall survival (OS) was 69% and 10-year disease-free survival (DFS) was 47%. Mean OS was 154 months (95% CI 131-171) and median OS was not reached (follow-up median 85 months (3-207)). Low-grade malignant histology (p = 0.001) and female gender (p = 0.045) were associated with improved OS. Almost equal OS and DFS were observed between patients treated with EPIC and HIPEC.
Conclusions: Patients treated for PMP with complete CRS and PIC achieved satisfactory long-term outcome. The most important prognostic factor was histopathological differentiation, but acceptable survival was observed even in patients with aggressive histology and extensive intraperitoneal tumor growth. Administration of EPIC and HIPEC was equally efficacious with respect to long-term outcome.
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