ABSTRACT
The spread of lymph from the tumor is typical and common in most of the carcinomas. It often occurs when these tumor cells from the primary cancer site are transported or drain to the adjacent lymph nodes through a system called lymphatic channels. This is often the first ladder in the spread of cancer in particular for carcinomas. When invaded by adjacent tumor cells, these lymph nodes usually get enlarged and these are known as regional lymph nodes because they drain in the region of the particular anatomical area in the head and neck. For most of the head and neck cancers, having enlarged lymph nodes clinically puts the staging of cancer into at least in stage III. Histopathologically positive lymph nodes reduce the probability of disease-free survival rate of five years by about flat 50% as compared to the disease that does not have positive lymph node and limited to the primary site in early stages. When the cancer spreads outside the capsule of lymph node of one or more number of lymph nodes and when these involved lymph nodes are situated in the lower triangle of neck, then they might be associated with a worse prognosis and higher incidence for distant metastasis. This chapter highlights the lymphatic system and its pathways and the classification of lymph nodes on head and neck.
