Staging Systems (Enneking, AJCC)

Staging Systems (Enneking, AJCC)

Prepared by Dr. Ahmet Mucteba YILDIRIM

Staging plays a crucial role in treatment planning and prognosis estimation for primary bone and soft tissue tumours. The two main systems used in orthopaedic oncology are:

Enneking Staging System (commonly used in surgical planning)

AJCC TNM Staging System (widely used in oncology)

 1. Enneking Staging – Bone Sarcomas

This system includes:

• Grade (G): Histological aggressiveness
• T (Tumour extension): Local vs extracompartmental
• M (Metastasis): Distant spread

 2. Grade Classification (Enneking) 

G1 (Low Grade):

• Mild atypia, mitosis <1/10 HPF
• Examples: ACT, parosteal osteosarcoma

G2 (High Grade):

• Distinct atypia, mitosis 1–2/10 HPF
• Examples: Classic osteosarcoma, Grade 2 chondrosarcoma

G3 (Anaplastic/Dedifferentiated):

• Marked atypia, mitosis >2/10 HPF
• Examples: Ewing sarcoma, undifferentiated chondrosarcoma

 3. T&M Definitions (Enneking)

• T1: Tumour within compartment
• T2: Extension to soft tissue, skip metastasis, or pelvic involvement
• M1: Presence of distant metastasis

 4. Enneking Stage Summary Table

• Stage IA
  Grade 1 (low grade)
  Tumour confined within the bone (T1)
  No metastasis (M0)
• Stage IB
  Grade 1
  Tumour has extended beyond the compartment (T2)
  No metastasis (M0)
• Stage IIA
  Grade 2 or 3 (high grade)
  Tumour confined (T1)
  No metastasis (M0)
• Stage IIB
  Grade 2 or 3
  Tumour has spread beyond compartment (T2)
  No metastasis (M0)
• Stage III
  Any grade
  Any tumour extent
  Distant metastasis present (M1)

 5. AJCC Staging – Bone Tumours (8th Edition)

More commonly used by oncologists. Uses:

• T (Tumour size)
• N (Lymph node involvement)
• M (Metastasis site: M1a = lung, M1b = other)
• Grade (G1–G4)

 6. T Category Definitions (AJCC)

T1: ≤5 cm
T2: >5–10 cm
T3: >10–15 cm
T4: >15 cm

 7. AJCC Bone Staging Table

StageTNMGradeIAT1N0M0G1–2IBT2–T3N0M0G1–2IIAT1N0M0G3–4IIBT2N0M0G3–4IIIT3N0M0G3–4IVAny TN1 or M1Any MAny G

 8. AJCC – Soft Tissue Sarcomas (Extremity & Trunk)

Uses TNM + Grade system. Version 8 no longer considers superficial vs deep location.

Grade Definitions:

• G1: Well-differentiated (e.g., liposarcoma)
• G2: Moderately differentiated (e.g., leiomyosarcoma)
• G3: Poorly/undifferentiated (e.g., pleomorphic or synovial sarcoma)

References

• Siegel, G. W., & Biermann, J. S. OKU: Musculoskeletal Tumours 5
• Choi, J. H., & Ro, J. Y. 2020 WHO Classification of Bone Tumours
• Tanaka, K., & Ozaki, T. AJCC 8th Edition – Bone & Soft Tissue Tumours

References

• Siegel, G. W., & Biermann, J. S. OKU: Musculoskeletal Tumours 5
• Choi, J. H., & Ro, J. Y. 2020 WHO Classification of Bone Tumours
• Tanaka, K., & Ozaki, T. AJCC 8th Edition – Bone & Soft Tissue Tumours