S1083 Assessing Predictors of Microvascular Invasion of HCC at Explant in Liver Transplantation

Abstract

INTRODUCTION: Liver transplant (LT) is curative in patients with cirrhosis complicated by hepatocellular cancer (HCC) within T2/Milan Criteria. Microvascular invasion (MVI) of HCC portends poor prognosis and is associated with higher risk of recurrence post LT; however, is often undetectable with multiphasic imaging modalities during pre-LT staging. Factors associated with the presence of MVI at LT remain poorly defined. Our aim is to examine pre-LT clinical demographic and tumor related factors and their association with MVI on explant at LT. METHODS: Retrospective evaluation identifying 154 consecutive patients undergoing LT with HCC over a 5-year timeframe (2012-2017). HCC explant pathologic specimen reports reviewed identifying tumor focality, site, size (greatest dimension), histologic type and grade; and presence/absence of microvascular and perineural invasion. Review allowed for stratification into MVI on explant and no MVI on explant groups. Demographic and tumor variables were collected for the MVI and no MVI groups assessing for differences in: age, days on wait-list ( > or < 365) , gender, race, BMI, etiology of cirrhosis, biologic model for end-stage liver disease (MELD) score, number of presenting lesions, tumor volume, type of locoregional therapy (LRT), response to initial and number of bridging therapies; categorical variables analyzed using Fisher’s exact test; continuous variables compared using Levine’s t-test for equal variances and student’s t-test; P < 0.05, significant. RESULTS: 154 LT recipients for HCC reviewed with 16 (10.4%) demonstrating MVI on explant. No significant demographic differences between MVI and non MVI groups apart from age 59 +/- 6 years vs 60+/- 6 years (P < 0.0001) [Table 1]. No significant differences in LRT modality or number of presenting lesions. Although trends associated with presence of MVI were seen (shorter wait times for LT, larger total tumor volume, and increased number of LRT sessions); differences did not reach significance between cohorts. CONCLUSION: Demographic and current staging modalities for HCC do not reliably capture or predict the phenomenon of MVI on explant. Presence of MVI may be associated with larger tumor volumes and shorter wait times. Results support the current approach of 6 month wait times for MELD exception points and call further attention to the unmet need for tissue or serum-based biomarkers in HCC prognosis.Table 1.: Characteristics of liver transplant patients