Serum core-fucosylated quiescin sulfhydryl oxidase 1 (cf-QSOX1) was found to be significantly associated with postoperative recurrence of HCC, and serum QSOX1 was shown to be completely represented by the 67 kDa short isoform of QSOX1 (QSOX1-S). Here, QSOX1 is linked to hepatocellular carcinoma.