Table 5. Summary of previous studies regarding hepatocellular carcinoma in young patients.

Author	Year	Country	Total N	Cutoff (years)	Proportion of young patients	Diagnosis	Treatment	Clinicopathologic findings	Prognostic finding
Shimada et al. [14]	2013	Japan	811	40	31 (3.8%)	Pathologically	liver resection	more frequent HBV, less frequent HCV, higher AFP levels, more cases with a maximum tumor size of >=5cm, more microscopic tumor thrombus in portal vein, more intrahepatic metastasis	not significant in OS and
Niederle et al. [9]	2012	Germany	1108	40	25 (2%)	Pathologically or clinically	variable	less common underlying chronic liver disease in young age group, higher AFP levels, more frequent fibrolamellar carcinoma	better OS (p = 0.048)
Takeishi et al. [10]	2011	Japan	610	40	13 (2.1%)	Pathologically	curative resection	more frequent HBV, less frequent HCV, higher platelet count, higher AFP levels, larger size, poorly differentiated, more portal vein invasion, more advanced stage, shorter operative time	tendency to better OS (p = 0.057) not significant in DFS (p = 0.762)
Chang et al. [8]	2008	Singapore	638	40	55 (8.6%)	Pathologically or clinically	variable	more frequent HBV, less frequent HCV, higher AFP levels, higher albumin, less cirrhosis, better child-Pugh class, more portal vein invasion, more advanced stage	tendency to better OS (p = NS) better OS in stage I-III (p = 0.025)
Yamazaki et al. [15]	2007	Japan	NA	40	20	Pathologically or clinically	variable	HBV 75%, Child Pugh Grade A 85%	eleven patients out of 20 died within 1 year
Cho et al. [12]	2007	Korea	320	30	71 (22%)	NA	NA	more frequent HBV, less frequent HCV, higher AFP levels, less cirrhosis, more advanced stage, more symptomatic patients	poor survival than other age groups (p = 0.007) - not significant after stage adjustment
Chen et al. [11]	2006	Taiwan	11,312	40	1229 (10.9%)	Pathologically or clinically	variable	more frequent HBV, less frequent HCV, larger size	paradoxical influence on survival worse 1 year survival (p < 0.001) better survival after 1 year (p < 0.001)
Kim et al. [3]	2006	Korea	4,234	30	38 (0.9%)	Pathologically or clinically	variable	low frequency of smoking history, more frequent HBV, less frequent HCV, higher AFP levels, well-preserved liver function, larger tumor size, more advanced stage, more frequent application of surgical resection and chemotherapy as initial treatment.	better OS than age group (40-59) (p = 0.04) similar OS with age group (>=60) better OS than other age groups in TNM stage I and II (p = 0.04)
Lam et al. [13]	2004	HongKong	1863	40	121 (6.5%)	clinically	variable	more frequently presented with pain, hepatomegaly, ruptured HCC/less frequently detected by routine screening/better Child-Pugh grading and ICG test/higher AFP level, larger tumor size, more frequent metastasis	shorter OS (p = 0.004)