Within 80 HCC tissues, circRNA_100338 displayed diverse expression levels despite high expression relative to pericancerous tissues; we thus further divided HCC patients into two groups according to their circRNA_100338 expression levels in HCC tissues (see Methods): circRNA_100338-low group (circRNA_100338/GAPDH ≤ 0.015, n = 51) and circRNA_100338-high group (circRNA_100338/GAPDH > 0.015, n = 29) and evaluated the patient cumulative survival rate in these two groups. Here, GAPDH is linked to hepatocellular carcinoma.