Clinical staging has an important role in predicting the clinical outcome and determining the most effective therapy for pediatric soft tissue sarcomas. As yet, there is no well-accepted staging system that is applicable to all childhood sarcomas; the system from the American Joint Commission for Cancer (AJCC) that is used for adults has not been validated in pediatric studies, however, the current Children's Oncology Group (COG) trial is using the AJCC staging system (see Tables 2-5 below) to facilitate comparison of results with other pediatric and adult soft tissue sarcoma trials. Two systems are currently in use for staging pediatric nonrhabdomyosarcomatous soft tissue sarcoma (NRSTS) tumors. The surgicopathologic staging system used by the Intergroup Rhabdomyosarcoma Study (see below) is based on the amount of tumor that remains after initial surgery and whether the disease has metastasized.
Group I: Tumor completely resected with histologically negative margins.
Group II: Grossly resected tumor with microscopic residual tumor.
- IIA: Grossly resected tumor with microscopic residual disease.
- IIB: Regional disease with involved nodes completely resected with no microscopic disease.
- IIC: Regional disease with involved nodes grossly resected but with evidence of residual microscopic disease and/or histologic involvement of the most distal regional lymph node in the dissection.
Group III: Incomplete resection or biopsy with gross residual tumor.
Group IV: Any localized or regional tumor with distant metastases present at the time of diagnosis.
- Any soft tissue sarcoma that recurs after initial treatment or progresses after radiation therapy, chemotherapy, or initial surgery.
The other schema typically used to stage pediatric soft tissue tumors is the TNM system of the International Union Against Cancer. In this staging system, T1 lesions are 5 cm or less in greatest dimension, and T2 lesions are more than 5 cm in greatest dimension. These categories can be subclassified to reflect the maximum tumor depth (a: superficial tumor; b: deep tumor). Regional nodal involvement is indicated by the N1 (N0: no regional nodal involvement) designation and the presence of distant metastases at the time of diagnosis is indicated by the M1 (M0: no metastatic involvement) designation.
TNM Stage Information
The American Joint Committee on Cancer (AJCC) has designated staging by the four criteria of tumor size, nodal status, grade, and metastasis (TNGM).
Table 2. Primary Tumor (T)a
a Reprinted with permission from AJCC: Soft tissue sarcoma. In: Edge SB, Byrd DR, Compton CC, et al., eds.: AJCC Cancer Staging Manual. 7th ed. New York, NY: Springer, 2010, pp 291-8.
b Superficial tumor is located exclusively above the superficial fascia without invasion of the fascia; deep tumor is located either exclusively beneath the superficial fascia, superficial to the fascia with invasion of or through the fascia, or both superficial yet beneath the fascia.
||Primary tumor cannot be assessed.
||No evidence of primary tumor.
||Tumor ?5 cm in greatest dimension.b
||Tumor >5 cm in greatest dimension.b