Serum alpha-fetoprotein as a predictive biomarker for tissue alpha-fetoprotein status and prognosis in patients with hepatocellular carcinoma

Background: Alpha-fetoprotein (AFP) expression is closely related to hepatocarcinogenesis, and it is an important prognostic factor for hepatocellular carcinoma (HCC). We aimed to investigate the relationship between serum AFP concentration and tissue AFP status and identify the prognostic value of serum and tissue AFP for HCC. Methods: This is a retrospective review of 248 patients with HCC from January 2012 to December 2018. Receiver operating characteristic (ROC) curves were plotted to investigate the predictive value of serum AFP for tissue AFP status. Overall survival (OS) was analyzed using the Kaplan-Meier method and log-rank tests were used for comparison between two groups. Multivariate Cox proportional hazards regression analysis was performed for various risk factors. Results: The serum AFP level in patients with tissue AFP-positive HCC was higher than those with tissue AFP-negative HCC (506.7 vs. 7.7 ng/mL, P<0.0001). Youden's index yielded an optimal cut-off value of serum AFP for tissue AFP status of 92.33 ng/mL with a sensitivity and specificity of 0.84 (95% CI: 0.74-0.90) and 0.88 (95% CI: 0.82-0.92), respectively. Moreover, high serum AFP concentrations (>_92.33 ng/mL) were significantly correlated with positive hepatitis B virus (HBV, P=0.012), tumor size (P=0.025) and histological grade (P=0.001); tissue AFP-positive status was associated with positive HBV (P=0.006), tumor number (P=0.033) and histological grade (P<0.001). Further, serum AFP level >_92.33 ng/mL and tissue AFP-positive status were associated with poorer OS, and positive HBV (Positive: HR 3.496; 95% CI: 1.349-9.064; P=0.010) and larger tumor size (>_5; HR 2.617; 95% CI: 1.372-4.992; P=0.003) were independent factors of OS. Conclusions: This study showed that serum AFP level could be a highly predictive biomarker for tissue AFP status in patients with HCC. Furthermore, serum AFP levels >_92.33 ng/mL and tissue AFP-positive status were associated with poorer OS but were not independent factors of OS.