Early Postoperative Intraperitoneal Chemotherapy for Low-Grade Appendiceal Mucinous Neoplasms with Pseudomyxoma Peritonei: Is it Beneficial?

There is little evidence for the use of early postoperative intraperitoneal chemotherapy (EPIC) in patients with low-grade appendiceal mucinous neoplasms (LAMNs) with pseudomyxoma peritonei (PMP). This study aims to assess the outcomes regarding the use of EPIC in a large cohort of patients with LAMNs with PMP uniformly treated by cytoreductive surgery (CRS) and perioperative intraperitoneal chemotherapy (PIC), all of whom received hyperthermic intraperitoneal chemotherapy (HIPEC), and most of whom also received EPIC. This was a retrospective study of prospectively collected data of consecutive patients with peritoneal carcinomatosis of appendiceal origin who underwent CRS and PIC by one surgical team at St George Hospital in Sydney, Australia, between January 1996 and November 2015. Subgroup analyses were performed for patients with a high Peritoneal Cancer Index (PCI) > 20 and also based on histopathological subtypes of LAMNs. A total of 250 patients formed the cohort of this study. No significant differences were observed in terms of hospital mortality (p = 0.153), major morbidity rate (i.e., grade III/IV; p = 0.593), intensive care unit stay (p = 0.764), and total hospital stay (p = 0.927); however, patients who received HIPEC + EPIC had a significantly longer stay in the high dependency unit. Multivariate analysis showed combined HIPEC with EPIC is an independent prognostic factor for better survival outcomes (hazard ratio 0.30, 95 % confidence interval 0.12-0.74; p = 0.009), adjusted for age, PCI, and histopathological subtypes. The combination of HIPEC + EPIC can provide additional survival benefits for patients with LAMNs with PMP compared with HIPEC alone, without increasing postoperative morbidity and mortality. EPIC should be considered following CRS and HIPEC for patients with LAMNs with PMP.