Clinical outcomes of hepatocellular carcinoma variants compared to hepatocellular carcinoma.

435 Background: There is no consensus regarding treatment for HCC variants. Clinical outcomes of HCC variants differ from pure HCC. The aim of this study is to compare clinicopathological characteristics, treatment, and outcomes of HCC variants with pure HCC. Methods: Patients with HCC and variants with 8170/3-8175/3 and 8180/3 ICD-O-3 codes were identified from National Cancer Database between 2004 and 2013. 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. The mean age was similar in all except FLHCC (37.9 vs. 60.9-64.1 years, p < 0.001). 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 (10.57%) underwent surgical resection less often than variants; FLHCC (54.8%), clear cell (34.5%), mixed HCC (29.8%), spindle cell (33.3%), pleomorphic (34.8%), and scirrhous (9.9%) (p < 0.001). Ablation was performed in 9.8% of pure HCC, and in up to 8.7% of HCC variants. More than a third of all patients received chemotherapy; pure HCC (42.3%), mixed HCC (38.5%), scirrhous (31.1%), spindle cell (36.1%), clear cell (35.5%), pleomorphic (34.8%), and FLHCC (41.3%). FLHCC had the best 5-year OS (38.7%), spindle cell and pleomorphic had the worst (9.6% and 13.0%). In univariate and multivariate analyses, fibrolamellar histology, female sex, diagnosis between 2009 and 2013, treatment at academic center, well/moderately differentiated histology, early stage, and chemotherapy was associated with better OS compared to pure HCC, male sex, diagnosis between 2004 and 2008, treatment at community cancer program, poorly differentiated, late stage, and no chemotherapy (p < 0.001). Conclusions: HCC variants underwent surgical resection more often than HCC. FLHCC had the best 5-year OS. Liver transplant is commonly performed in HCC variants.