CT scan is more accurate in predicting viable disease after microwave ablation then tace in patients undergoing locoregional treatment in hepatocellular carcinoma

Abstract

Presenter: Maria Baimas-George MD, MPH | Carolinas HealthCare System Background: The use of locoregional therapies such as laparoscopic tumor ablation or intra-arterial chemotherapy in hepatocellular carcinoma (HCC) to achieve local control, reduce transplant list dropout, downstage, or reduce recurrence is common practice. Assessing tumor response after treatment, however, remains difficult and unreliable without an explant specimen. We sought to determine the accuracy of imaging in treatment success after locoregional therapy in HCC. Methods: Patients with HCC who underwent either microwave ablation (MWA) and/or transarterial chemoembolization (TACE) prior to hepatectomy or transplantation were retrospectively identified from 2008 to 2018. Computed tomography (CT) scans after treatment and prior to resection were evaluated for characteristics consistent with viable tumor. The explant specimen was identified, and tumor response was assessed through pathologic evaluation. The accuracy of the pre-operative CT scan readings was compared with the pathologic findings of the explant specimen. Results: Ninety-one patients were identified who underwent locoregional treatment prior to resection or transplant. Of these, 14 patients underwent laparoscopic MWA, 46 underwent TACE, and 31 underwent both treatments in a neoadjuvant fashion. The ability of CT imaging to predict tumor viability was assessed by treatment modality. For MWA, CT scans demonstrated a 75% positive predictive value (PPV) and a 67% negative predictive value (NPV). This correlated with a 50% sensitivity and 86% specificity. For TACE, CT scans demonstrated an 87% positive predictive value (PPV) and a 25% negative predictive value (NPV). This correlated with an 82% sensitivity and 33% specificity. For MWA-TACE, CT scans demonstrated an 80% positive predictive value (PPV) and a 39% negative predictive value (NPV). This correlated with a 42% sensitivity and 78% specificity. Conclusion: Imaging to guide response to locoregional therapies in HCC has variable accuracy. There is a high probability of finding tumor given a positive CT scan after all three treatment modalities, whereas a negative CT scan is unreliable. Specifically, CT imaging after MWA demonstrates a high specificity and will likely rule out any residual tumor and CT imaging after TACE is highly sensitive and will likely find residual tumor.