Early and long-term outcome data on 2,298 patients with pseudomyxoma peritonei of appendiceal origin treated by a strategy of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy.

532 Background: Pseudomyxoma peritonei (PMP) originating from an appendiceal mucinous neoplasm remains a biologically heterogeneous disease. The purpose of this study was to evaluate the outcome and long-term survival after cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) consolidated through an International Registry study. METHODS A retrospective multi-institutional registry was established through collaborative efforts of participating units affiliated with the Peritoneal Surface Oncology Group International (PSOGI). RESULTS 2298 patients from 16 specialized units underwent CRS for PMP. Treatment related mortality was 2% and major operative complication was 24%. The median survival was 196 months (16.3 years) and the median progression-free survival was 98 months (8.2 years) with a 10- and 15-year survival rate of 63% and 59% respectively. Multivariate analysis identified prior chemotherapy treatment (P<0.001), PMCA histopathological subtype (P<0.001), major postoperative complication (P=0.008), high PCI (P=0.013), debulking surgery (CCR2/3) (P<0.001), not using HIPEC (P=0.030) as independent predictors for a poorer progression-free survival. Older age (P=0.006), major postoperative complication (P<0.001), debulking surgery (CCR2/3) (P<0.001), prior chemotherapy treatment (P=0.001) and PMCA histopathological subtype (P<0.001) were independent predictors of a poorer overall survival. CONCLUSIONS The combined modality strategy for PMP may be performed safely with acceptable morbidity and mortality in a specialized unit setting with 63% of patients surviving beyond 10-years. Minimizing non-definitive operative and systemic chemotherapy treatments prior to definitive cytoreduction may facilitate the feasibility and outcome of this therapy to achieve long-term survival. Optimal cytoreduction achieves the best outcomes.