Accuracy and clinical relevance of computed tomography scan interpretation of peritoneal cancer index in colorectal cancer peritoneal carcinomatosis: A multi‐institutional study

Abstract

Background Evaluation of peritoneal metastases by computed tomography (CT) scans is challenging and has been reported to be inaccurate. Methods A multi‐institutional prospective observational registry study of patients with peritoneal carcinomatosis from colorectal cancer was conducted and a subset analysis was performed to examine peritoneal cancer index (PCI) based on CT and intraoperative exploration. Results Fifty‐two patients (mean age 52.6 ± 12.4 years) from 16 institutions were included in this study. Inaccuracies of CT‐based assessment of lesion sizes were observed in the RUQ (P = 0.004), LLQ (P < 0.0005), RLQ (P = 0.003), distal jejunum (P = 0.004), and distal ileum (P < 0.0005). When CT‐PCI was classified based on the extent of carcinomatosis, 17 cases (33%) were underestimations, of which, 11 cases (21%) were upstaged from low to moderate, 4 cases (8%) were upstaged from low to severe, and 2 cases (4%) were upstaged from moderate to severe. Relevant clinical discordance where an upstage occurred to severe carcinomatosis constituted a true inaccuracy and was observed in six cases (12%). Conclusions The actual clinical impact of inaccuracies of CT‐PCI was modest. CT‐PCI will remain as a mandatory imaging tool and may be supplemented with other tools including positron emission tomography scan or diagnostic laparoscopy, in the patient selection for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy. J. Surg. Oncol. 2010;102:565–570.