Classification of Tumors According to Their Spread

Stage O: Preinvasive carcinoma in situ,
Stage I: Early local invasion, no metastases,
Stage II: Limited local tumor spread with minimal regional lymph node infestation,
Stage III: Extensive local tumor infestation with extensive regional lymph node infestation, possibly already inoperable.
Stage IV: Normally inoperable extensive spread of the tumor and severe infestation of lymph nodes; or any finding with distant metastases without consideration of local tumor spread.