Rhabdomysarcoma

Rhabdomyosarcoma (RMS or ‘rhabdo’) is a tumor made up of cancerous muscle cells called rhabdomyoblasts. In the United States, about 350 new cases are diagnosed each year in children less than 15 years of age. Almost two-thirds of RMS cases develop in children under the age of 10.

RMS may arise in any muscle in the body, but the most common sites for this tumor are:

  • Adjacent to the base of the skull (parameningeal)
  • Around the eye (orbital)
  • Other sites in the head and neck, such as the nose and throat (nasopharngeal)
  • Arms and legs (extremities)
  • Urinary system and reproductive sexual organs (GU, or genitourinary: includes bladder, vagina, prostate and paratesticular sites)1

 

Staging of Rhabdomyosarcoma

 

Childhood rhabdomyosarcoma is staged by using three different ways to describe the cancer:

  • A staging system.
  • A grouping system.
  • A risk group.

The staging system is based on the size of the tumor, where it is in the body, and whether it has spread to other parts of the body:

Stage 1: In stage 1, cancer is any size, has not spread to lymph nodes, and is found in only one of the following "favorable" sites:

  • Eye or area around the eye.
  • Head and neck (but not in the tissue next to the brain and spinal cord).
  • Gallbladder and bile ducts.
  • In the testes or vagina (but not in the kidney, bladder, or prostate).

Rhabdomyosarcoma that occurs in a "favorable" site has a better prognosis. If the site where cancer occurs is not one of the favorable sites listed above, it is said to be an "unfavorable" site.

Stage 2: In stage 2, cancer is found in any one area not included in stage 1. The tumor is 5 centimeters or smaller and has not spread to lymph nodes.

Stage 3: In stage 3, cancer is found in any one area not included in stage 1 and one of the following is true:

  • The tumor is 5 centimeters or smaller and cancer has spread to nearby lymph nodes.
  • The tumor is larger than 5 centimeters and cancer may have spread to nearby lymph nodes.

Stage 4: In stage 4, the tumor may be any size and cancer may have spread to nearby lymph nodes. Cancer has also spread to distant parts of the body such as the lung, bone marrow, or bone.

The grouping system is based on whether the cancer has spread and how much cancer remains after surgery to remove the tumor:

Group I

Cancer was found only in the place where it started and it was completely removed by surgery. Tissue was taken from the edges of where the tumor was removed. The tissue was checked under a microscope by a pathologist and no cancer cells were seen.

Group II

Group II is divided into groups IIA, IIB, and IIC.

  • IIA: Cancer was removed by surgery but cancer cells were seen when the tissue, taken from the edges of where the tumor was removed, was viewed under a microscope by a pathologist.
  • IIB: Cancer had spread to nearby lymph nodes and the cancer and lymph nodes were removed by surgery.
  • IIC: Cancer had spread to nearby lymph nodes and the cancer and lymph nodes were removed by surgery. Tissue was taken from the edges of where the tumor was removed. The tissue was checked under a microscope by a pathologist and no cancer cells were seen.

Group III

Cancer was partly removed by surgery and there are cancer cells (a lump or mass) remaining that can be seen by x-ray or other imaging test. Cancer has not spread to distant parts of the body.

Group IV

Cancer had spread to distant parts of the body at the time of diagnosis. The risk group is based on the staging system and the grouping system and is used to plan treatment. The risk group describes the chance that rhabdomyosarcoma will recur (come back). The following risk groups are used:

Low-risk childhood rhabdomyosarcoma

Low-risk childhood rhabdomyosarcoma is one of the following:

  • An embryonal tumor of any size that is found in a "favorable" site. There may be tumor remaining after surgery that can be seen without a microscope. The cancer may have spread to nearby lymph nodes. The following areas are "favorable" sites:
    • Eye or area around the eye.
    • Head or neck (but not in the tissue next to the brain and spinal cord).
    • Gallbladder and bile ducts.
    • In the testes or vagina (but not in the kidney, bladder, or prostate).
  • An embryonal tumor of any size that is not found in one of the "favorable" sites listed above. There may be tumor remaining after surgery that can be seen only with a microscope. The cancer may have spread to nearby lymph nodes.

Intermediate-risk childhood rhabdomyosarcoma

Intermediate-risk childhood rhabdomyosarcoma is one of the following:

  • An embryonal tumor of any size that is not found in one of the "favorable" sites listed above. There is tumor remaining after surgery, that can be seen with or without a microscope. The cancer may have spread to nearby lymph nodes.

  • An alveolar tumor of any size in a "favorable" or "unfavorable" site. There may be tumor remaining after surgery that can be seen with or without a microscope. The cancer may have spread to nearby lymph nodes.

High-risk childhood rhabdomyosarcoma

High-risk childhood rhabdomyosarcoma may be the embryonal type or the alveolar type. It may have spread to nearby lymph nodes and has spread to one or more distant parts of the body.

 

Treatment of Rhabdomyosarcoma

 

Three types of standard treatment are used:

  • Surgery
  • Radiation therapy
  • Chemotherapy

 

New types of treatment are being tested in clinical trials

 

  • High-dose chemotherapy with stem cell transplant
  • Immunotherapy
  • Targeted therapy2

Search for clinical trials in Georgia.

References for this page:

1Children’s Oncology Group (COG) at: http://www.curesearch.org/for_parents_and_families/newlydiagnosed/article.aspx?ArticleId=3135&StageID=1&TopicId=1&Level=1. (Accessed July 2016)

2Adapted from the National Cancer Institute's PDQ Database: http://www.cancer.gov/cancertopics/pdq/treatment/childrhabdomyosarcoma/Patient/page1. (Accessed July 2016)