A new and rare type of hepatocellular carcinoma: Survival and gene analysis of portal vein tumour thrombus-type hepatocellular carcinoma.

Background: Portal vein tumour thrombus (PVTT) in patients with hepatocellular carcinoma (HCC) is known as a major complication associated with poor survival. We clinically defined a new and rare type of HCC, PVTT-type HCC (PVTT-HCC), in a small group of HCC patients with HCC presenting only as PVTT without a demonstrable parenchyma tumour. The clinicopathological and biological features of PVTT-HCC are not clear.
Methods: The data for patients who had PVTT-HCC with histologically confirmed HCC from January 2004 to December 2012 at the Eastern Hepatobiliary Surgery Hospital were retrospectively analysed. The survival outcomes of patients with PVTT-HCC were compared with those of HCC patients with PVTT (HCC-PVTT). Propensity score matching (PSM) analysis was performed to match patients at a ratio of 1:3. Then, we performed RNA-Seq analysis of liver samples from PVTT-HCC and HCC-PVTT patients to identify and compare differentially expressed genes and biological pathways between the two groups.
Results: We observed and collected 10 rare cases of PVTT-HCC and performed a prospective cohort study to compare overall survival (OS) between PVTT-HCC and HCC-PVTT. PVTT invaded the main portal vein in 10 PVTT-HCC patients. Univariate and multivariate analyses demonstrated that ChildPugh (A/B), different treatments (LR/non-LR), and different groups were independent risk factors for OS. The median OS was 10.3 months (95 % CI = 6.7-13.8) in the HCC-PVTT group and 7.5 months (95 % CI = 2.8-12.1) in the PVTT-HCC group (P = 0.042). From RNA-Seq, 1630 differentially expressed genes were obtained, of which 731 were upregulated and 899 downregulated in PVTT-HCC compared with HCC-PVTT.
Conclusions: The survival outcomes of patients with PVTT-HCC were worse than those of patients with HCC-PVTT. RNA-Seq demonstrated differential gene expression between PVTT-HCC and HCC-PVTT, indicating that the former may have distinguishing biological characteristics and be a new and rare type of HCC.
Competing Interests: Conflict of interest statement The authors who participate in this study have no conflicts of interest to declare.
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