Number of Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) Treatments is Associated with Longer Survival

Objective: To analyze the reasons for stopping pressurized intraperitoneal aerosolized chemotherapy (PIPAC) delivered for unresectable peritoneal surface malignancies (PSM) and to determine survival in a large patient cohort of an experienced PIPAC center. Background: PIPAC alone or combined with systemic chemotherapy was developed to palliatively treat unresectable PSM. Safety, tolerance and promising survival results were already reported, but the reasons for stopping treatment remain unclear and the influence of the number of PIPAC procedures on prognosis has not been evaluated. Methods: A retrospective analysis of PIPAC procedures from a prospectively maintained single institution PSM database was conducted from January 2016 to January 2023. Results: A total of 346 patients underwent 1200 PIPAC treatments in the defined time period. Two-thirds of the patients completed 3 or more PIPAC procedures, and 2 patients had more than 15 treatment procedures. Reasons for PIPAC cessation were disease progression or complication (56%), reorientation to a potential curative procedure (19%), surgical complications of the procedure (13%), death between procedures (8%) and patient request (3%). PSM origin and receiving 3 or more PIPAC treatments were independently correlated with better survival in the overall population, in the group of ultimately unresectable PSM and after propensity score weighting. Conclusion: The main reason for stopping PIPAC treatment in palliative management of PSM is disease progression. When 3 or more PIPAC procedures can be delivered in combination to systemic chemotherapy, survival is significantly improved. Its use should be validated by prospective studies.