Hepatocellular carcinoma biology predicts survival outcome after liver transplantation in the USA.

Purpose: The aim of this study is to evaluate the clinicopathologic prognostic factors of cancer-specific survival (CSS) in hepatocellular carcinoma (HCC) patients who underwent liver transplantation (LT) stratified by tumor size.

Methods: From the Surveillance, Epidemiology, and End Results (SEER) 18 registries (2004-2012), we retrieved data of 570 patients who underwent LT for a solitary primary HCC lesion ≤5 cm. A two multivariable Cox models were constructed to identify prognostic factors of CSS in a two different tumor sizes (2 cm cutoff).

Results: Out of 570 HCC patients (median age 57 years), 16% had microvascular invasion (MVI) and 12% had a poorly differentiated tumor. Male sex (odds ratio [OR] 2.6), tumor size >2 cm (OR 1.78), elevated AFP (OR 2.31), and poor tumor differentiation (OR 2.59) are significant predictors of MVI. With a median follow up of 41.5 months (range 1-107 months), the 5-year CSS rate was 90% in the absence of MVI compared to 75% in the presence of MVI (p<0.001). Multivariate models revealed that age ≥60 years (hazard ratio [HR] 2.08), MVI (HR 2.26), and poor tumor differentiation (HR 2.42), were significant risk factors of a dismal CSS with HCC size >2 cm, but not with HCC ≤2 cm.

Conclusions: Primary HCC tumor size ≤2 cm had an excellent prognosis after LT and was not affect by the presence of MVI or poor tumor differentiation.