The importance of primary tumor origin in gastrointestinal malignancies undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy

Background: Appendiceal and colorectal cancers with peritoneal carcinomatosis (PC) can derive benefit from cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). However, its role in gastric and small bowel malignancies remains undefined. Methods: We retrospectively analyzed 251 gastrointestinal adenocarcinomas with PC which underwent CRS/HIPEC at our institution from 2007 to 2017. We compared outcomes of gastric, small bowel, appendiceal, and colorectal cohorts. Results: Thirty-one gastric, 8 small bowel, 91 appendiceal, and 121 colorectal cohorts were included. More gastric cancers (90%) received neoadjuvant chemotherapy than any other cohort, p = 0.002. Although colorectal had the lowest peritoneal cancer index (PCI) (9) and appendiceal the highest (16), all cohorts underwent similar rates of organ resection and complete cytoreduction. Length of stay (p = 0.005) and major perioperative morbidity (Clavien III/IV, p = 0.011) were significantly higher in gastric and small bowel. Median overall survival (OS, p < 0.001) was significantly shorter in gastric (13 months) and small bowel (9 months) than in appendiceal (33 months) and colorectal (42 months) cohorts. On multivariate analysis, complete cytoreduction and PCI score were significant predictors of OS, p < 0.05. Conclusions: Primary tumor origin significantly affects outcomes after CRS/HIPEC for gastrointestinal malignancies. Though there was a survival benefit in appendiceal and colorectal, gastric and small bowel survival was comparable to systemic chemotherapy.