Progression of pseudomyxoma peritonei after combined modality treatment: management and outcome.

Background: Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment strategy for pseudomyxoma peritonei (PMP) with curative intent. The aim of this study was to determine the patterns of failure in patients who underwent such a procedure and to evaluate management and outcome of progressive disease.

Methods: After exclusion of patients with overt malignancy, progression was studied in 96 PMP patients treated primarily by CRS with HIPEC. Location, pathology, management and outcome were recorded.

Results: Median follow-up was 51.5 months (0.1-99.5). Median progression free survival (PFS) was 28.2 months (95% CI 18.3->). Progressive disease was mainly located sub hepatic (38%) or in multiple regions (36%). Pathological dedifferentiation was observed in 8 patients (20%). The choice of treatment depended on pathology, extent of disease and PFS. Seventeen patients were treated for progression by second CRS with (n=8) or without HIPEC (n=10). The 3-years overall survival (OS) probability after this treatment was 100% and 53.3% (95% CI 28.2-100%), respectively. Fifteen patients with (slow) progression were observed. Three-years OS probability of these patients was 66.0% (95% CI 43.4-100%). All patients treated for progression by systemic chemotherapy only (n=6) had died of disease after a median follow up of 14.8 (9.8-33.6) months. A longer PFS after primary treatment was associated with longer OS after progression (P = 0.04).

Conclusions: Progressive PMP after primary CRS with HIPEC is probably the result of technical failure and/or tumor biology. Management of progressive PMP can be valuable for selected patients and should depend primarily on the PFS.