HIF1A and neoplasm: However, when TACE induces tumor necrosis, it can also aggravate hypoxia at the tumor site, which leads to upregulation of hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF), thus resulting in tumor-associated angiogenesis, tumor recurrence and metastasis [5, 6].