Correlation of Tumor Response on Computed Tomography With Pathological Necrosis in Hepatocellular Carcinoma Treated by Chemoembolization Before Liver Transplantation

The purpose of this article was to compare the results of Response Evaluation Criteria in Solid Tumors (RECIST), modified Response Evaluation Criteria in Solid Tumors (mRECIST), and European Association for the Study of the Liver (EASL) criteria for the evaluation of tumor necrosis in patients treated with transarterial chemoembolization before liver transplantation (LT) for hepatocellular carcinoma. Response to treatment was evaluated on computed tomography scan by 2 independent readers based on RECIST, mRECIST, and EASL criteria, and compared with tumor necrosis assessed by explant pathology. Necrosis was defined as major when >90%. Factors associated with major necrosis were tested by multivariate analysis. Fifty-eight patients (53 males; mean age, 54 years; range, 31-64 years) were included with 88 nodules. Fifty-one (58%) nodules were shown to have major necrosis. Among them readers 1 and 2 identified a complete response (CR) according to RECIST, mRECIST, and EASL criteria in 2 (4%), 47 (92%), and 47 (92%), and 1 (2%), 45 (88%), and 45 (88%) nodules, respectively. However, 12-14 of 59 nodules classified as CR on mRECIST or EASL criteria were found to have intermediate or minor necrosis (overestimation in 20%-24% of the patients). Combining the classification of CR by mRECIST and EASL criteria and complete lipiodol deposition reduced the overestimation to 11%. Among 59 nodules classified with a CR according to mRECIST or EASL, those with complete lipiodol deposition (n = 36, 61%) had a higher rate of necrosis than those with incomplete lipiodol deposition (n = 23, 39%): 95% versus 68% and 95% versus 63% for reader 1 and 2, respectively. In conclusion, CR based on mRECIST/EASL combined with complete lipiodol deposition was better for identification of major tumor necrosis. Even in the presence of CR according to mRECIST/EASL, incomplete lipiodol deposition should be considered indicative of substantial viable tumor remnant.