Outcomes After Adjuvant Hyperthermic Intraperitoneal Chemotherapy for High-Risk Primary Appendiceal Neoplasms After Complete Resection

Introduction. Appendiceal neoplasms are uncommon tumors. Optimal treatment for patients with perforation or high-grade pathology after initial resection is unknown. This study evaluated patients with increased risk for peritoneal dissemination after primary resection, but no evidence of peritoneal disease, who underwent adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC). Methods. This multi-institutional cohort study evaluated 56 patients with high-risk (HR) appendiceal neoplasms with a peritoneal carcinomatosis index of 0 who underwent HIPEC. The patients were divided into two groups: perforated low-grade appendiceal (LGA) carcinoma and HR neoplasms, which included perforated high-grade appendiceal carcinoma, positive margins after initial resection, minimal macroscopic peritoneal disease that was previously resected or completely responded to systemic chemotherapy prior to HIPEC, goblet cell carcinoma, and adenocarcinoma with signet ring cell features. Overall survival (OS) and recurrence-free survival (RFS) were estimated by Kaplan-Meier analysis. Results. Thirty-eight percent of patients had perforated LGA and 68% had HR features. Five-year OS probability was 82.1% for the entire cohort, and 100% and 70.1% for patients with perforated LGA and HR features, respectively (p = 0.024). Five-year RFS probability was 79.3% for the entire cohort, and 90.0% and 72.4% for patients with perforated LGA and HR features, respectively (p = 0.025). Eight patients recurred after HIPEC and their OS was significantly worse (p < 0.001). Conclusion. While adjuvant HIPEC is both safe and feasible, there appears to be little benefit over close surveillance when outcomes are compared with historical and prospective studies, especially for perforated LGA carcinoma.