Childhood Rhabdomyosarcoma Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Stage Information
Table 1. Definition of Terms continued...
Staging of rhabdomyosarcoma is relatively complex. The process includes the following steps:
- Assigning a Stage: Determined by primary site, tumor size (widest diameter), and presence or absence of regional lymph node and/or distant metastases.
- Assigning a local tumor Group: Determined by status postsurgical resection/biopsy, with pathologic assessment of the tumor margin and of lymph node disease.
- Assigning a Risk Group: Determined by Stage, Group, and histology.
As noted previously, prognosis for children with rhabdomyosarcoma depends predominantly on the primary site, tumor size, Group, and histologic subtype. Favorable prognostic groups were identified in previous Intergroup Rhabdomyosarcoma Study Group (IRSG) studies, and treatment plans were designed on the basis of assignment of patients to different treatment groups according to prognosis. Several years ago, the IRSG merged with the National Wilms Tumor Study Group and two large cooperative pediatric cancer treatment groups to form the Children's Oncology Group (COG). New protocols for children with soft tissue sarcoma are developed by the Soft Tissue Sarcoma Committee of the COG (COG-STS).
Current COG-STS protocols for rhabdomyosarcoma use the TNM-based pretreatment staging system that incorporates the primary tumor site, presence or absence of tumor invasion of surrounding tissues, tumor size, regional lymph node status, and the presence or absence of metastases. This staging system is described in Table 2 below.[6,7]
Table 2. Soft Tissue Sarcoma Committee of the Children's Oncology Group: Pretreatment Staging System
|Stage||Sites of Primary Tumor||T Stage||Tumor Size||Regional Lymph Nodes||Distant Metastasis|
|N0 = absence of nodal spread; N1 = presence of regional nodal spread beyond the primary site; X = unknown N status; M0 = absence of metastatic spread; M1 = presence of metastatic spread beyond the primary site and regional lymph nodes; T1 = tumor confined to anatomic site of origin (noninvasive); T2a = tumor extension and/or fixation to surrounding tissue (invasive), tumor ≤5 cm in maximum diameter; T2b = tumor extension and/or fixation to surrounding tissue (invasive), tumor >5 cm in maximum diameter.|
|1||Favorable sites||T1 or T2||Any size||N0 or N1 or NX||M0|
|2||Unfavorable sites||T1 or T2||a, ≤ 5 cm||N0 or NX||M0|
|3||Unfavorable sites||T1 or T2||a, ≤ 5 cm||N1||M0|
|b, > 5 cm||N0 or N1 or NX|
|4||Any site||T1 or T2||Any size||N0 or N1 or NX||M1|
The IRS-I, IRS-II, and IRS-III studies prescribed treatment plans based on the Surgical-pathologic Group system. In this system, Groups are defined by the extent of disease and by the completeness or extent of initial surgical resection after pathologic review of the tumor specimen(s). The definitions for these Groups are shown in Table 3 below.[8,9]