 Involvement of the cervical lymph nodes with metastatic cancer is the single most important prognostic factor in head and neck squamous cell carcinoma and may be associated with a halving of survival.Where the cancer has penetrated the capsule of the lymph gland (extracapsular extension) survival may be decreased by a further 50%.Other important factors are the level, the number of nodes and their size, which are also correlated with the risk of distant metastases.