Prediction of Resectability in Pseudomyxoma Peritonei with a New CT Score

Curative treatment of pseudomyxoma peritonei (PMP) is complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). The aim of this study was to build and evaluate a preoperative imaging score to predict resectability. Between 2007 and 2014, all PMP patients in two tertiary reference centers who underwent laparotomy with intent to undergo CRS and HIPEC were included in this study retrospectively. Thickness of tumor burden was measured on preoperative multidetector-row computed tomography (MDCT) by two radiologists blinded to surgical results in five predetermined areas. Patients were divided into two cohorts with the same resectability rate (building and validation). The performances of the scores were assessed using receiver operating characteristic (ROC) curve analyses. Overall, 126 patients were included, with compete CRS being achieved in 91/126 patients (72.2%). Two cohorts of 63 patients matched by age, sex, burden of disease, resectability rate, and pathological grade were constituted. The MDCT score was the sum of the five measures, and was higher in unresectable disease [median 46.2 mm (range 27.9-74.6) vs. 0.0 mm (range 0.0-14.0), p < 0.001]. Area under the ROC curve was 0.863 (range 0.727-0.968) and 0.801 (range 0.676-0.914) in the building and validation cohorts, respectively. A threshold of 28 mm yielded a sensitivity, specificity, positive predictive and negative predictive value of 94, 81, 81 and 94% in the building cohort, and 80, 68, 59 and 85% in the validation cohort, respectively. Using our score, overall and disease-free survival were increased in the group classified as resectable. A simple preoperative MDCT score measuring tumor burden in the perihepatic region is able to predict resectability and survival of PMP patients.