Grading

Grading (cell differentiation): The term refers to the degree of histological malignancy.

G1 means high differentiation (good prognosis, because highly differentiated tumors with a low degree of malignancy (in practice: bronchial carcinoids, rarely also squamous epithelial or azinic (berry-shaped) adenocarcinomas))

G2 mean differentiation, mean highly differentiated tumors with mean malignancy (in practice: mostly bronchial wall gland carcinomas, rarely also squamous epithelial or papillary adenocarcinomas)

G3 extensive de-differentiation (poor prognosis, because little differentiated tumors with high degree of malignancy (in practice: depending on staging) all advanced non-small-cell lung carcinomas).

G4 undifferentiated tumors with very high degree of malignancy (in practice: depending on staging all small cell lung carcinomas).