Insight into Predictors of Cytoreduction Score Following Cytoreductive Surgery-Hyperthermic Intraperitoneal Chemotherapy for Gastric Peritoneal Carcinomatosis Improves Patient Selection and Prognostic Outcomes

Background Peritoneal metastases due to gastric adenocarcinoma (GCPM) carry a dismal prognosis. A promising treatment strategy is cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC), but clear eligibility criteria for GCPM are lacking. We sought to identify factors associated with overall survival (OS) following CRS-HIPEC for GCPM to help optimize patient selection and clinical outcomes. Patients and Methods In this single-center retrospective cohort study, we examined CRS-HIPEC outcomes for patients with GCPM between 2001 and 2021. After analyzing patient demographic, clinicopathologic, and perioperative variables, we applied multivariable Cox hazard models to assess factors associated with OS. We then assessed associations between baseline predictors and prognostically important variables using multivariable logistic regression. Results We analyzed 55 patients with GCPM who underwent CRS-HIPEC. Median age was 54 years and 42% were female. Median peritoneal carcinomatosis index (PCI) was 8, and 75% of patients achieved a cytoreduction completeness score (CC score) of 0. Median progression-free survival (PFS) was 6.9 months, and median OS was 14.1 months. On adjusted analysis, a CC score > 0 (HR 2.3, p = 0.02) was significantly associated with worse OS. A peritoneal carcinomatosis index greater than 13 (OR 52.6, p = 0.001) and fewer lymph nodes (especially < 18) resected with the primary tumor (OR 0.86, p = 0.042) in the metachronous setting were significantly associated with incomplete macroscopic cytoreduction (CC score > 0). Conclusions We demonstrated that PCI > 13 and primary lymph nodes harvested < 18 in metachronous tumors are associated with CC score > 0, which in turn portends a worse OS. Although these results warrant prospective validation, they provide insight into improved selection of patients with GCPM for CRS-HIPEC.