Table 2.

HPV-positive and HPV-negative HNSCC molecular profiles

Molecular change	HPV-positive	HPV-negative
Viral DNA integration into host DNA	yes	no
DNA lesions (carcinogen adducts, breaks)	background level	frequently detected
Mutations in crucial genes e.g. TP53	infrequent, no	frequent
Failure of TP53 suppressor function	binding of cellular proteins by viral proteins: E6 (p53) and E7 (Rb)	dysfunction protein produced by mutated gene
TP16 expression	overexpression	common low expression following gene methylation
Loss of heterozygosity	uncommon	frequent
Chromosome instability	induction of centrosome instability	increased general instability
Chromosome aberrations	occasional chromosome loss	gross deletions
Oncogenic pathway	disrupting p53 and pRb molecular pathways	carcinogen exposure → DNA lesion → mutation → mutator phenotype → cancer