Clinical outcomes of rare hepatocellular carcinoma variants compared to pure hepatocellular carcinoma

BACKGROUND: HCC variants are rare primary hepatic tumors. The aim of this study is to compare clinical characteristics and outcomes of HCC variants with pure HCC. METHODS: Patients diagnosed between 2004 and 2013 with ICD-O-3 8180/3 and 8170/3-8175/3 were identified from the National Cancer Database. Univariate and multivariate survival analyses were conducted to analyze the association between histology and overall survival (OS). RESULTS: 80,280 patients were identified; pure HCC 78,461 (97.7%), fibrolamellar (FLHCC) 310 (0.4%), scirrhous 161 (0.2%), spindle cell 72 (0.1%), clear cell 487 (0.6%), pleomorphic 23 (0.0%), and combined HCC and cholangiocarcinoma (mixed HCC) 766 (1.0%). 76.7% were male and 72% Caucasian. Liver transplant was performed in 10.1% of pure HCC, 14.5% of mixed HCC, 16.2% of scirrhous, 6.9% of spindle cell, 8.8% of clear cell, 8.7% of pleomorphic, and 3.2% of FLHCC (p<0.001). Pure HCC (10.6%) underwent surgical resection without transplant less often than variants except for scirrhous (9.9%) (p<0.001). More than a third of patients in each histological type received chemotherapy. FLHCC had the best 5-year OS (38.7%), spindle cell and pleomorphic had the worst (9.6% and 13.0%). In multivariate analysis stratified by histology variants, chemotherapy was associated with improved OS in all histologies except for scirrhous and pleomorphic HCC. CONCLUSION: HCC variants underwent surgical resection more often than pure HCC. FLHCC had the best 5-year OS. Liver transplant was commonly performed in HCC variants.