Before biopsy of a suspected tumor mass, imaging studies of the mass and baseline laboratory studies should be obtained. After the diagnosis of rhabdomyosarcoma has been made, an extensive evaluation to determine the extent of the disease should be done prior to instituting therapy. This evaluation should include a chest x-ray, computed tomography (CT) scan of the chest, bilateral bone marrow aspirates and biopsies, bone scan, magnetic resonance imaging of the base of the skull and brain (for parameningeal primary tumors only), and CT scan of the abdomen and pelvis (for lower extremity or genitourinary primary tumors). Positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (FDG) scans identify areas of possible metastatic disease not seen by other imaging modalities. If proof of these metastatic sites might change therapy, than these sites should be biopsied so as to confirm this finding.[1][Level of evidence: 3iiDii]

One study has demonstrated that sentinel lymph node biopsies can be safely performed in children with rhabdomyosarcoma, and positive biopsies may alter the treatment plan.[2]

Terms used in this summary section are defined below in Table 1.

Table 1. Definition of Terms

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Term	Definition
Favorable site	Orbit; nonparameningeal head and neck; genitourinary excluding kidney, bladder, and prostate; biliary tract.
Unfavorable site	Any site not considered favorable.
T1	Tumor confined to anatomic site of origin.
T2	Tumor extension and/or fixative to surrounding tissue.
a	Tumor ≤5 cm in maximum diameter.
b	Tumor >5 cm in maximum diameter.
N0	No clinical regional lymph node involvement.
N1	Clinical regional lymph node involvement.
NX	Regional lymph nodes not examined; no information.
M0	No metastatic disease.
M1	Metastatic disease.

Staging of rhabdomyosarcoma is relatively complex. The process includes:

1. Assigning a local tumor group (status postsurgical resection/biopsy).
2. Assigning stage (consider site, size, group, presence/absence of metastases).
3. Assigning a risk group (consider stage, group, and histology).

As noted previously, prognosis for children with rhabdomyosarcoma is dependent on the primary site, size, group, and histologic subtype. Favorable prognostic groups have been identified by previous Intergroup Rhabdomyosarcoma Studies (IRS), and treatment plans have been designed based on assignment of patients to different groups based on prognosis. The IRS-I, IRS-II, and IRS-III studies prescribed treatment plans based on a surgical pathologic grouping system. In this system, groups are defined by the extent of disease and by the extent of initial surgical resection after pathologic review of the tumor specimen(s). The definitions of these groups in the IRS-I, IRS-II, and IRS-III studies are given in Table 2 below.[3,4]

Table 2. IRS Group Surgicopathologic Grouping System

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Group	Definition
I  [Note: Approximately 13% of all patients are in this group.]	A localized tumor that is completely removed with pathologically clear margins and no regional lymph node involvement.
II  [Note: Approximately 20% of all patients are in this group.]	A localized tumor that is grossly removed with: (A) microscopic disease at the margin, (B) involved, grossly removed regional lymph nodes, or (C) both A and B.
III  [Note: Approximately 48% of all patients are in this group.]	A localized tumor with gross residual disease after incomplete removal or biopsy only.
IV  [Note: Approximately 18% of all patients are in this group.]	Distant metastases are present at diagnosis.

The Intergroup Rhabdomyosarcoma Study Group (IRSG) has merged with the National Wilms Tumor Study Group and with the 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 (STS-COG).

Current STS-COG protocols for rhabdomyosarcoma utilize a TNM-based pretreatment staging system which incorporates the surgicopathologic group, primary tumor site, regional lymph node status, and the presence or absence of metastases. This staging system is described in Table 3 below.[5,6]

Table 3. STS-COG Pretreatment Staging System

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Stage	Sites of Primary Tumor	T Stage	Tumor Size	Regional Lymph Nodes	Distant Metastasis
1	Favorable sites	T1 or T2	Any size	N0 or N1 or NX	M0
2	Unfavorable sites	T1 or T2	T1a or T2a	N0 or NX	M0
3	Unfavorable sites	T1 or T2	T1a, T2a	N1	M0
			T1b, T2b	N0 or N1 or NX
4	Any site	T1 or T2	Any size	N0 or N1	M1

Following stage assignment, a risk group is assigned. This takes into account stage, group, and histology. Patients are classified for protocol purposes as low risk, intermediate risk, or high risk.[7,8] Treatment assignment is based on risk group. Table 4 shows the current risk group classification.

Table 4. IRSG Rhabdomyosarcoma Risk Group Classification

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Risk Group	Histology	Stage	Group
Low Risk	Embryonal	1	I, II, III
	Embryonal	2, 3	I, II
Intermediate Risk	Embryonal	2, 3	III
	Alveolar	1, 2, 3	I, II, III
High Risk	Embryonal or Alveolar	4	IV

 [Note: Since 2006, patients with undifferentiated sarcoma are treated on the STS-COG protocol for non-rhabdomyosarcomatous soft tissue sarcoma.]

References

1. Völker T, Denecke T, Steffen I, et al.: Positron emission tomography for staging of pediatric sarcoma patients: results of a prospective multicenter trial. J Clin Oncol 25 (34): 5435-41, 2007.  [PUBMED Abstract]
   
   
2. Kayton ML, Delgado R, Busam K, et al.: Experience with 31 sentinel lymph node biopsies for sarcomas and carcinomas in pediatric patients. Cancer 112 (9): 2052-9, 2008.  [PUBMED Abstract]
   
   
3. Crist WM, Garnsey L, Beltangady MS, et al.: Prognosis in children with rhabdomyosarcoma: a report of the intergroup rhabdomyosarcoma studies I and II. Intergroup Rhabdomyosarcoma Committee. J Clin Oncol 8 (3): 443-52, 1990.  [PUBMED Abstract]
   
   
4. Crist W, Gehan EA, Ragab AH, et al.: The Third Intergroup Rhabdomyosarcoma Study. J Clin Oncol 13 (3): 610-30, 1995.  [PUBMED Abstract]
   
   
5. Lawrence W Jr, Gehan EA, Hays DM, et al.: Prognostic significance of staging factors of the UICC staging system in childhood rhabdomyosarcoma: a report from the Intergroup Rhabdomyosarcoma Study (IRS-II). J Clin Oncol 5 (1): 46-54, 1987.  [PUBMED Abstract]
   
   
6. Lawrence W Jr, Anderson JR, Gehan EA, et al.: Pretreatment TNM staging of childhood rhabdomyosarcoma: a report of the Intergroup Rhabdomyosarcoma Study Group. Children's Cancer Study Group. Pediatric Oncology Group. Cancer 80 (6): 1165-70, 1997.  [PUBMED Abstract]
   
   
7. Raney RB, Anderson JR, Barr FG, et al.: Rhabdomyosarcoma and undifferentiated sarcoma in the first two decades of life: a selective review of intergroup rhabdomyosarcoma study group experience and rationale for Intergroup Rhabdomyosarcoma Study V. J Pediatr Hematol Oncol 23 (4): 215-20, 2001.  [PUBMED Abstract]
   
   
8. Breneman JC, Lyden E, Pappo AS, et al.: Prognostic factors and clinical outcomes in children and adolescents with metastatic rhabdomyosarcoma--a report from the Intergroup Rhabdomyosarcoma Study IV. J Clin Oncol 21 (1): 78-84, 2003.  [PUBMED Abstract]
   
   

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