A neck dissection also depends on the tumor size, thickness, location of tumor, tumor histology or grade, if it's midline on the tongue, base of tongue, other areas, and the base of tongue, tonsils have a high propensity to metastasise due to the high lymphatics they are, as well as
HPV metastising early to the nodes, which tumors may bigger than the primary itself, and and other negative prognostic findings like extracapsular spread, invasion, perineural invasion, lymphovascular invasion.
