Prognostic and clinicopathological significance of hypoxia-inducible factors 1α and 2α in hepatocellular carcinoma: a systematic review with meta-analysis

BACKGROUND: Hepatocellular carcinoma (HCC) is a highly recurrent tumor after resection and has been closely related to hypoxia. Hypoxia-inducible factors 1α and 2α (HIF-1α and HIF-2α) have been shown to contribute to tumor progression and therapy resistance in HCC. We evaluated the prognostic and clinicopathological significance of HIF-1α and HIF-2α in HCC patients. METHODS: We systematically searched Embase, Cochrane, PubMed, Scopus and Web of Science (WOS) from inception to 1 June 2020 for studies evaluating HIF-1α and/or HIF-2α expression in HCC. Selected articles evaluate at least one factor by immunohistochemistry (IHC) in HCC patients who underwent surgical resection, and its relationship with prognosis and/or clinicopathological features. Study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CDR42020191977). We meta-analyzed the data extracted or estimated according to the Parmar method employing STATA software. We evaluated the overall effect size for the hazard ratio (HR) and odds ratio (OR) with 95% confidence interval (CI), as well as heterogeneity across studies with the I(2) statistic and chi-square-based Q test. Moreover, we conducted subgroup analysis when heterogeneity was substantial. Publication bias was assessed by funnel plot asymmetry and Egger’s test. RESULTS: HIF-1α overexpression was correlated with overall survival (OS), disease-free survival (DFS)/recurrence-free survival (RFS) and clinicopathological features including Barcelona Clinic Liver Cancer (BCLC), capsule infiltration, intrahepatic metastasis, lymph node metastasis, tumor–node–metastasis (TNM), tumor differentiation, tumor number, tumor size (3 cm), vascular invasion and vasculogenic mimicry. We also detected a possible correlation of HIF-1α with alpha-fetoprotein (AFP), cirrhosis, histological grade, tumor size (5 cm) and albumin after subgroup analysis. Initially, only DFS/RFS appeared to be associated with HIF-2α overexpression. Subgroup analysis denoted that HIF-2α overexpression was related to OS and capsule infiltration. CONCLUSIONS: HIF-1α and HIF-2α overexpression is related to poor OS, DFS/RFS and some clinicopathological features of HCC patients, suggesting that both factors could be useful HCC biomarkers.