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Table 3 TNM staging system for bone tumours

From: Guidelines for histopathological specimen examination and diagnostic reporting of primary bone tumours

T - Primary tumour     
TX Primary tumour cannot be assessed    
T0 No evidence of primary tumour    
T1 Tumour 8 cm or less in greatest dimension    
T2 Tumour more than 8 cm in greatest dimension    
T3 Discontinuous tumours in the primary bone site    
N - Regional lymph nodes     
NX Regional lymph nodes cannot be assessed    
N0 No regional lymph node metastasis    
N1 Regional lymph node metastasis    
M - Distant metastasis     
MX Distant metastasis cannot be assessed    
M0 No distant metastasis    
M1 Distant metastasis    
M1a Lung    
M1b Other distant sites    
G - Histologic grade     
GX Grade cannot be assessed    
G1 Well differentiated - low grade    
G2 Moderately differentiated - low grade    
G3 Poorly differentiated - high grade    
G4 Undifferentiated - high grade*    
Stage grouping     
Stage Tumour (T) Node (N) Metastasis (M) Grade (G)
Stage IA T1 NO MO G1, 2 low grade
Stage IB T2 NO MO G1, 2 low grade
Stage IIA T1 NO MO G3, 4 high grade
Stage IIB T2 N0 MO G3, 4 high grade
Stage III T3 NO MO Any G
Stage IVA Any T NO M1a Any G
Stage IVB Any T N1 Any M Any G
  Any T Any N M1b Any G
  1. *Ewing's sarcoma is classified as high grade.