Prolonged Survival in Peritoneal Metastatic Appendiceal Carcinoma Patients Treated With Combined Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

INTRODUCTION: Primary treatment for peritoneal dissemination of appendiceal cancer is the combination of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. The endpoints were overall survival and evaluation of prognostic factors. METHODS: Clinicopathological and treatment-related factors were obtained from a prospective database. A total of 84 patients, 55 (65%) primary and 29 (35%) recurrent malignant appendiceal carcinomas with synchronous and metachronous peritoneal metastases, underwent multimodal treatment between 2011 and 2021. The endpoints of the study were overall survival and evaluation of prognostic factors. RESULTS: The median follow-up was 4.8 y; the mean age was 54.5 y (range 25-77), with a sex distribution of 69% female and 31% male. The mean peritoneal cancer index was 11.3. The proportion of mucinous, intestinal-type, signet ring cell, and goblet cell carcinoma was 56%, 23%, 11%, and 10%, respectively. The 5-y survival rate of the whole cohort was 56.7%. In primary and recurrent diseases, the overall median survival was 8.4 and 4.9 y. Significantly improved survival was detected after complete cytoreduction resection (hazard ratio [HR] for CCR-2 versus CCR-0: 9.388, 95% confidence interval [CI] 3.026-29.124, P = 0.001) and initial local operation with undelayed admission to the center (HR 0.262, 95% CI 0.089-0.773; P = 0.015). The five independent factors in Kaplan-Meier analysis and univariable Cox regression analysis associated with significant adverse survival were cancer antigen (CA) 19-9 over 37 IU/mL, signet ring cell and intestinal-type histology, positive nodal status, grading, and peritoneal cancer index >20. Neoadjuvant chemotherapy administration did not impact survival (HR 1.220, 95% CI 0.612-2.432, P = 0.571). CONCLUSIONS: With multimodal treatment, prolonged survival is attainable in stage IV primary and recurrent appendiceal carcinoma with peritoneal dissemination. Direct referral to specialized centers after confirmation of peritoneal metastasis is recommended because prompt definitive treatment may significantly improve survival.