Neoadjuvant Pressurized Intraperitoneal Aerosol Chemotherapy for Conversion to Cytoreductive Surgery in Unresectable Malignant Peritoneal Mesothelioma: A Report of 2 Cases

BACKGROUND Peritoneal mesothelioma (PM) is the second most common presentation site of malignant mesothelioma. The standard of care for PM is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). Because of its insidious manifestations, PM is often diagnosed at advanced, unresectable stages, precluding optimal cytoreduction and diminishing long-term survivability. CASE REPORT We report 2 cases of advanced and unresectable PM (stages III and IV) presenting with symptomatic with low-grade epithelioid disease. Both cases had a high peritoneal cancer index (PCI >30) and extensive small-bowel involvement. The patients underwent pressurized intraperitoneal aerosol chemotherapy (PIPAC) with cisplatin and doxorubicin as downstaging conversion therapy. Patient 1 was a 47-year-old man with a laparoscopic PCI of 34 and progression of disease despite 5 months of systemic intravenous chemotherapy. After 2 cycles of PIPAC, the patient showed disease regression and complete resolution of large ascites; CRS-HIPEC was feasible with complete cytoreduction (CC-0). The patient was discharged after a 60-day hospital stay. Patient 2 was a 43-year-old man with a laparoscopic PCI of 30 and no prior lines of therapy. After a single PIPAC cycle, there was clear disease regression (PCI=23), allowing CRS-HIPEC with optimal cytoreduction (CC-1). The patient was discharged after 10 days. CONCLUSIONS PIPAC is established as a suitable option for palliation of massive ascites in PM; however, in selected candidates with favorable prognostic biomarkers and appropriate fitness for surgery, the procedure can serve as a bridge to definitive open surgery (CRS-HIPEC) aimed at achieving complete cytoreduction.