Oncologic Risk Stratification Following Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Appendiceal Carcinomatosis

Patients with peritoneal carcinomatosis (PC) of appendiceal origin demonstrate variable oncologic outcomes, despite aggressive cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). We sought to devise a prognostic risk stratification system for oncologic outcomes following CRS-HIPEC. A total of 197 patients undergoing CRS-HIPEC for the treatment of appendiceal PC were reviewed from a prospective database. Kaplan-Meier survival curves and multivariate Cox regression models were used to identify prognostic factors affecting oncologic outcomes. Clinicopathologic variables affecting overall survival (OS) were utilized to develop a prognostic staging system and nomograms. Univariate and multivariate Cox regression analysis indicated that high-grade tumor histology, lymph node metastasis, and incomplete cytoreduction were high-risk features, adversely affecting OS. Patients were stratified on the presence of high-risk features as follows: low-risk patients had no risk factors (n = 102); intermediate-risk patients had one risk factor (n = 49); and high-risk patients had more than one risk factor (n = 46). Median OS for low-risk patients was not reached, and was 43 and 22 months for intermediate-risk and high-risk patients, respectively. Five-year OS was 72, 43, and 13 % for low-, intermediate- and high-risk patients, respectively (p < 0.0003 for low vs. intermediate risk, and p = 0.06 for intermediate vs. high risk). We propose a three-tier staging system for appendiceal PC following CRS-HIPEC, based on histologic grade, lymph node involvement, and completeness of cytoreduction. The presence of any one or more of these high-risk features significantly decreased survival in our single-institution database and provided the basis for a prognostic staging system and corresponding nomograms.