Modified RECIST to assess tumor response after transarterial chemoembolization of hepatocellular carcinoma: CT-pathologic correlation in 178 liver explants

Abstract

Purpose: To retrospectively evaluate agreement between modified RECIST (mRECIST) assessed at Computed Tomography (CT) and pathology in a large series of patients with hepatocellular carcinoma (HCC) who were transplanted after transarterial chemoembolization (TACE).

Materials and methods: IRB approval was obtained. The study included 178 patients (M/F=155/23; mean age 55.8 ± 6.3 years) with HCC who were transplanted after TACE from January 1996 to December 2010 and with at least one CT examination before liver transplantation (LT). Two blinded independent readers retrospectively reviewed CT examinations, to assess tumor response to TACE according to mRECIST. Patients were classified in responders (complete and partial response) and non-responders (stable and progressive disease). On the explanted livers, percentage of tumor necrosis was classified as 100, >50 and <50%.

Results: The mean interval between latest CT and LT was 57.4 ± 39.8 days. At latest CT examination, the objective response rate was 78.1% (139/178), with 86 cases (48.3%) of complete response (CR). A good intra- (k=0.75 and 0.86) and inter-observer (k=0.81) agreement was obtained. On a per-patient basis, agreement between mRECIST and pathology was obtained in 120 patients (67.4%), with 19 cases (10.7%) of underestimation and 39 cases (21.9%) of overestimation of tumor response at CT. CT sensitivity and specificity in differentiating between responders and non-responders were 93 and 82.9%, respectively. Out of 302 nodules, sensitivity and specificity of CT in detecting complete necrosis were 87.5 and 68.9%, respectively.

Conclusions: CT can overestimate tumor response after TACE. Nonetheless, mRECIST assessed at CT after TACE are reproducible and reliable in differentiating responders and non-responders.