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

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.

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.

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).

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.