Outcomes of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemoperfusion in Patients with High-Grade, High-Volume Disseminated Mucinous Appendiceal Neoplasms

Background: High-grade (HG) mucinous appendiceal neoplasms (MAN) have a worse prognosis than low-grade histology. Our objective was to assess the safety and efficacy of cytoreductive surgery with hyperthermic intraperitoneal chemoperfusion (CRS/HIPEC) in patients with high-grade, high-volume (HG–HV) peritoneal metastases in whom the utility of this aggressive approach is controversial. Methods: Prospectively collected perioperative data were compared between patients with peritoneal metastases from HG–HV MAN, defined as simplified peritoneal cancer index (SPCI) ≥12, and those with high-grade, low-volume (HG–LV; SPCI <12) disease. Kaplan–Meier curves and multivariate Cox regression models identified prognostic factors affecting oncologic outcomes. Results: Overall, 54 patients with HG–HV and 43 with HG–LV peritoneal metastases underwent CRS/HIPEC. The HG–HV group had longer operative time, increased blood loss/transfusion, and increased intensive care unit length of stay (p < 0.05). Incomplete macroscopic cytoreduction (CC-1/2/3) was higher in the HG–HV group compared with the HG–LV group (68.5 vs. 32.6 %; p = 0.005). Patients with HG–HV disease demonstrated worse survival than those with HG–LV disease (overall survival [OS] 17 vs. 42 m, p = 0.009; time to progression (TTP) 10 vs. 14 m, p = 0.024). However, when complete macroscopic resection (CC-0) was achieved, the OS and progression-free survival of patients with HG–HV disease were comparable with HG–LV disease (OS 56 vs. 52 m, p = 0.728; TTP 20 vs. 19 m, p = 0.393). In a multivariate Cox proportional hazard regression model, CC-0 resection was the only significant predictor of improved survival for patients with HG–HV disease. Conclusions: Although patients with HG–HV peritoneal metastases from MAN have worse prognosis compared with patients with HG–LV disease, their survival is comparable when complete macroscopic cytoreduction is achieved.