Table 2.

Extrinsic factors associated with HNSCC pathogenesis.

Function	Factors	Refs no in foot note
1. Mitogens, adhesion and motility molecules,and proteases	TGF‐α, Amphiregurlin, HGF, IGF, PDGF, ILs, MMPs, chemokines	[1]
2. Non‐cancerous cells in stroma	Bone marrow derived cells, cancer associated fibroblast, tumor associated macrophage,Treg	[2]
3. Angiogenesis	VEGF, PDGF	[3]
4. Extracellular metabolism	acidosis, hypoxia, ROS	[4]
5. Immune response	Rantes, IP‐10, TNF‐α, IFN‐γ, VEGF	[5]

References: 1 ‐ Barnes et al. (2007), Bran et al. (2009), Hunter et al. (2005), Knowles et al. (2009), Reuter et al. (2007). 2 ‐ De Boeck et al. (2010), Strauss et al. (2007), Tabachnyk et al. (2012); 3 ‐ Bran et al. (2009), Matta and Ralhan (2009); 4 ‐ Hoogsteen et al. (2007); 5 ‐ Jewett et al. (2006).