There are many types of childhood cancer with different symptoms and treatments. Childhood cancer survival rates in the United States have increased from less than 20 percent in the 1960s to almost 80 percent today. Parents are the best advocates for their children so being informed will help guide a family to make the best decisions for the child battling cancer.
Rhabdomyosarcoma is the most common soft tissue sarcoma in children accounting for about 3% of childhood cancers. This tumor starts in the same embryonic cells that develop into striated (voluntary) muscles. It can happen in the head and neck, groin, abdomen, pelvis, arms and legs. It may cause pain, swelling (a lump), or both. Rhabdomyosarcoma occurs in two distinct age groups: children five years of age and under, who are most likely to have the embryonal form of disease; and adolescent children aged 14-20, who more often have alveolar rhabdomyosarcoma. The overall five-year survival rate for rhabdomyosarcoma is 70% when detected in an early, treatable stage.
Sarcomas are cancers that occur in the soft tissues of the body. Rhabdomyosarcoma (RMS) affects cells called rhabdomyoblasts, immature cells which go on to form the skeletal muscles of the body. Although it is the most common soft tissue cancer in children, only about 350 cases are diagnosed each year in the United States.
Embryonal tumors are most frequently found in the head and neck area, eye orbit, genitals and bladder. They are most common in children under the age of five. Seventy-five percent of rhabdomyoscarcomas are of this type.
Alveolar tumors are more likely to be seen in adolescents. More than one-third occur in the extremities (arms and legs), and less frequently in the head and neck, pelvis and trunk. More aggressive therapy is required to treat this form of rhabdomyosarcoma.
Symptoms depend on the location of the tumor:
Standard Rhabdomyosarcoma Treatment (additional new types of treatments are being tested in clinical trials and can be found on the NCI Web site): The treatments listed below are to be used as a suggestion of what you may expect. Please speak with your doctor about specific treatment plans he or she may have for your child.
In addition, new types of treatments are often being tested in clinical trials and can be found on the National Cancer Institute Website.
Staging of rhabdomyosarcoma is relatively complex. The process includes the following steps:
1. Assigning a stage (consider site, size, Surgico-pathologic Group, and presence/absence of metastases).
2. Assigning a local tumor Surgico-pathologic Group (status postsurgical resection/biopsy, with pathologic assessment of the tumor margin).
3. Assigning a Risk Group (classified by Stage, Group, and histology).
As noted previously, prognosis for children with rhabdomyosarcoma depends 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 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 (COG-STS).
Current COG-STS protocols for rhabdomyosarcoma use a TNM-based pretreatment staging system that incorporates the Surgico-pathologic Group, primary tumor site, regional lymph node status, and the presence or absence of metastases. This staging system is described in Table 2 below.[4,5]
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
I Favorable sites T1 or T2 Any size N0 or N1 or NX M0
II Unfavorable sites T1 or T2 a, ≤ 5 cm N0 or NX M0
III Unfavorable sites T1 or T2 a, ≤ 5 cm N1 M0
b, > 5 cm N0 or N1 or NX
IV Any site T1 or T2 Any size N0 or N1 or NX M1
M0 = absence of metastatic spread; M1 = presence of metastatic spread beyond the primary site; N0 = absence of nodal spread; N1 = presence of nodal spread beyond the primary site; X = unknown N status.
The IRS-I, IRS-II (POG-7898), and IRS-III studies prescribed treatment plans based on the Surgico-pathologic Group 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 for these Groups are shown in Table 3 below.[6,7]
Table 3. Soft Tissue Sarcoma Committee of the Children’s Oncology Group Surgico-pathologic Group System
I (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 (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 (Approximately 48% of all patients are in this group.) A localized tumor with gross residual disease after incomplete removal or biopsy only.
IV (Approximately 18% of all patients are in this group.) Distant metastases are present at diagnosis.
After patients are categorized by Stage and Surgico-pathologic Group, a Risk Group is assigned. This takes into account Stage, Group, and histology. Patients are classified for protocol purposes as having a low risk, intermediate risk, or high risk of disease recurrence.[8,9] Treatment assignment is based on Risk Group, as shown in Table 4. To be considered alveolar histology, the tumor must have greater than 50% alveolar elements; if the alveolar component is 50% or less, the tumor is considered embryonal.
Table 4. Soft Tissue Sarcoma Committee of the Children’s Oncology Group Rhabdomyosarcoma Risk Group Classification
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 sarcomas are treated on the COG-STS protocol for non-rhabdomyosarcomatous soft tissue sarcoma. Refer to the PDQ summary on Childhood Soft Tissue Sarcoma for more information.]
MD Anderson Childhood Cancer Types. Houston, TX: MD Anderson. Retrieved August 15, 2011 from http://www.mdanderson.org/patient-and-cancer-information/
National Institute of Health. Types of Cancers 2011. Retrieved September 13, 2011 from http://www.cancer.gov/cancertopics/pdq/treatment
American Cancer Society. Cancer Facts and Figures 2009. Atlanta, GA: American Cancer Society. Retrieved September 1, 2011, from http://www.cancer.org/downloads/STT/CAFF2009PWSecured.pdf.
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