The 'N' component of the TNM system describes the involvement of regional lymph nodes. It is crucial because the spread of cancer to lymph nodes often indicates a higher stage of disease:
N0: No regional lymph node involvement. N1-N3: Increasing involvement of regional lymph nodes. N1 might indicate a small number of affected nodes, while N3 could denote extensive regional lymph node involvement.
Histological examination of lymph node biopsies is essential for accurate staging.
