Grade and TNM Definitions
AJCC Stage Groupings

Staging has an important role in determining the most effective treatment of soft tissue sarcomas. The stage is determined by the size of the tumor, the histologic grade, and whether it has spread to lymph nodes or distant sites. Intracompartmental or extracompartmental extension of extremity sarcomas is also important for surgical decision making. For complete staging, a thorough physical examination, x-rays, laboratory studies, and careful review of all biopsy specimens (including those from the primary tumor, lymph nodes, or other suspicious lesions) are essential. Computed tomographic scan of the chest is recommended for sarcomas larger than 5 cm (T2) or with moderate to poor differentiation (grades 2–4). Nodal involvement is rare, occurring in less than 3% of patients with sarcoma.[1]

The American Joint Committee on Cancer (AJCC) has designated staging by the four criteria of tumor size, nodal status, grade, and metastasis (TNGM).[2]

Tumor grade (G)

• GX: Grade cannot be assessed
• G1: Well differentiated
• G2: Moderately differentiated
• G3: Poorly differentiated
• G4: Poorly differentiated or undifferentiated

Primary tumor (T)

• TX: Primary tumor cannot be assessed
• T0: No evidence of primary tumor
• T1: Tumor 5 cm or less in greatest dimension
  • T1a: Superficial tumor
  • T1b: Deep tumor
• T2: Tumor 5 cm or larger in greatest dimension
  • T2a: Superficial tumor
  • T2b: Deep tumor

 [Note: Superficial tumor is located exclusively above the superficial fascia without invasion of the fascia; deep tumor is located either exclusively beneath the superficial fascia, or superficial to the fascia with invasion of or through the fascia, or both superficial yet beneath the fascia. Retroperitoneal, mediastinal, and pelvic sarcomas are classified as deep tumors.]

Regional lymph nodes (N)

• NX: Regional lymph nodes cannot be assessed
• N0: No regional lymph node metastasis
• N1: Regional lymph node metastasis  [Note: Presence of positive nodes (N1) is considered stage IV.]

Distant metastasis (M)

• MX: Distant metastasis cannot be assessed
• M0: No distant metastasis
• M1: Distant metastasis

Stage I

Stage I tumor is defined as low-grade, superficial, and deep.

• G1, T1a, N0, M0
• G1, T1b, N0, M0
• G1, T2a, N0, M0
• G1, T2b, N0, M0
• G2, T1a, N0, M0
• G2, T1b, N0, M0
• G2, T2a, N0, M0
• G2, T2b, N0, M0

Stage II

Stage II tumor is defined as high-grade, superficial, and deep.

• G3, T1a, N0, M0
• G3, T1b, N0, M0
• G3, T2a, N0, M0
• G4, T1a, N0, M0
• G4, T1b, N0, M0
• G4, T2a, N0, M0

Stage III

Stage III tumor is defined as high-grade, large, and deep.

• G3, T2b, N0, M0
• G4, T2b, N0, M0

Stage IV

Stage IV is defined as any metastasis to lymph nodes or distant sites.

• Any G, any T, N1, M0
• Any G, any T, N0, M1

References

1. Fong Y, Coit DG, Woodruff JM, et al.: Lymph node metastasis from soft tissue sarcoma in adults. Analysis of data from a prospective database of 1772 sarcoma patients. Ann Surg 217 (1): 72-7, 1993.  [PUBMED Abstract]
   
   
2. Soft tissue sarcoma. In: American Joint Committee on Cancer.: AJCC Cancer Staging Manual. 6th ed. New York, NY: Springer, 2002, pp 193-7.