Table 1.

Overview of differences in cellular processes between HPV-positive and HPV-negative HNSCC.

Cellular Processes	HPV-Positive HNSCC	HPV-Negative HNSCC
Angiogenesis	Increased levels of HIF-1α [52,53,54] Inverse correlation with angiogenic factors [19,20]	Higher levels of angiogenic factors [19,20]
Metabolism	Higher rates of oxidative phosphorylation, mostly in the tumor core [22,55,56]	Higher rates of glycolysis, mostly in the tumor core [22,55,56]
DNA Damage Response	Impaired DNA DSB repair with less HR and more NHEJ [14,18,57,58,59]	Enhanced DNA DSB repair [14,18,57,58,59]
Immune Response	Higher rate of active immune cells [22,23,24,25]	Lower rate of active immune cells [22,23,24,25]
Cell Death Mechanisms	p53 suppression by HPV oncogene E6 [4,5,60]	p53 mutations [3,61,62]

HIF-1α: Hypoxia inducible factor-1α, DNA DSB: DNA double strand breaks, HR: Homologous recombination, NHEJ: Non-homologous end-joining.