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Rhabdomyosarcoma

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Staging rhabdomyosarcoma

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. Extent includes:

  • where the tumour started (called the site of the primary tumour)
  • the size of the tumour
  • whether or not the tumour has grown into, or invaded, nearby tissue
  • if the cancer has spread to lymph nodes
  • if the cancer has spread to other parts of the body

Your healthcare team uses this information to determine the stage. They also consider where the cancer has spread and how much of the cancer was removed with surgery to determine the clinical group. They use the type of rhabdomyosarcoma, stage and clinical group to divide children into risk groups, which are used to plan treatment and estimate prognosis (outcome of the treatments).

Stages

The most common staging system for rhabdomyosarcoma is based on the site of the primary tumour, size of the tumour and the TNM system. Each stage is given a number from 1 to 4.Generally, the higher the number, the more the cancer has spread.

Site of the primary tumour

Doctors describe the site of the primary tumour as favourable or unfavourable. Favourable sites have a better prognosis. Unfavourable sites have a poorer, or less favourable, prognosis.

Favourable sites include the:

  • area around the eye (called the orbit)
  • eyelid
  • head and neck but not areas near the meninges (tissue surrounding the brain and spinal cord) – also called non-parameningeal sites
  • ovaries, fallopian tubes, uterus, cervix, vagina, the area adjacent to the testicles (paratesticular), penis, ureters or urethra
  • organs in the biliary tract (including the gallbladder and bile ducts)

 

Unfavourable sites include all other sites such as:

  • the kidney
  • the bladder
  • the prostate
  • muscles in an arm or leg
  • the head and neck close to the meninges (tissue surrounding the brain and spinal cord), including the nasal passages, paranasal sinuses, middle ear and the back of the upper throat – also called parameningeal sites
  • muscles in the trunk (chest or abdomen)
  • the retroperitoneum

Size of the tumour

Tumour size is described as a or b. a means the tumour is 5 cm or less at its greatest diameter. b means the tumour is more than 5 cm at its greatest diameter.

TNM descriptions

T describes the tumour. T1 means the tumour is non-invasive. It has not spread from where it started. T2 means the tumour is invasive. It touches, has grown into or is attached to surrounding tissue.

 

N describes the number and location of any lymph nodes close to the tumour (called regional lymph nodes) that have cancer cells in them. N0 means cancer hasn’t spread to any nearby lymph nodes. N1 means cancer has spread to nearby lymph nodes.

M describes whether or not the cancer has spread, or metastasized, to other parts of the body. M0 means that cancer has not spread to other parts of the body. M1 means that it has spread to other parts of the body.

Stage 1

Site of the primary tumourTumour sizeTNMDescription

favourable

a or b (any size)

T1 or T2

N0 or N1

M0

The tumour is in a favourable site. It can be any size. It may be non-invasive or invasive. The cancer may have spread to regional lymph nodes. It hasn’t spread to other parts of the body.

Stage 2

Site of the primary tumourTumour sizeTNMDescription

unfavourable

a (5 cm or less in diameter)

T1 or T2

N0

M0

The tumour is in an unfavourable site. It is 5 cm or less in diameter. It may be non-invasive or invasive. The cancer has not spread to regional lymph nodes. It hasn’t spread to other parts of the body.

Stage 3

Site of the primary tumourTumour sizeTNMDescription

unfavourable

a (5 cm or less in diameter)

T1 or T2

N1

M0

The tumour is in an unfavourable site. It is 5 cm or less in diameter. It may be non-invasive or invasive. The cancer has spread to regional lymph nodes. It hasn’t spread to other parts of the body.

b (more than 5 cm in diameter)

T1 or T2

N0 or N1

M0

The tumour is in an unfavourable site. It is more than 5 cm in diameter. It may be non-invasive or invasive. The cancer may have spread to regional lymph nodes. It hasn’t spread to other parts of the body.

Stage 4

Site of the primary tumourTumour sizeTNMDescription

any

a or b (any size)

T1 or T2

N0 or N1

M1

The tumour is in any site and is any size. It may be non-invasive or invasive. The cancer may have spread to regional lymph nodes. The cancer has spread to other parts of the body.

Recurrent rhabdomyosarcoma

Recurrent rhabdomyosarcoma means that the cancer has come back after it has been treated. If it comes back in the same place where the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called distant metastasis, or distant recurrence.

Clinical groups

Clinical groups are assigned after surgery according to the Intergroup Rhabdomyosarcoma Study (IRS) group system. This system is based on whether or not the cancer has spread and how much of the cancer was removed during surgery. Each group is given a number from 1 to 4. Groups 1 to 4 are usually given as the Roman numerals I, II, III and IV. Generally, the higher the number, the more the cancer has spread.

GroupDescription

I

The tumour is localized, which means that it has not spread to other parts of the body. It was completely removed with surgery.

II

The tumour is localized. It was removed with surgery, but cancer cells were found at the margin between the cancer and the surrounding healthy local tissue that was removed with the tumour, nearby lymph nodes or both.

III

The tumour wasn’t completely removed with surgery. The cancer may have spread to nearby lymph nodes, but not to distant organs.

IV

When it was diagnosed, the cancer had already spread to other parts of the body, such as the lungs, the liver, the bones, the bone marrow, distant muscles or distant lymph nodes.

Risk groups

The Soft Tissue Sarcoma Committee of the Children’s Oncology Group (STSC-COG) assigns children diagnosed with rhabdomyosarcoma to risk groups. These risk groups help the doctor determine prognosis and plan the best treatment approach. The risk groups are based on the type of rhabdomyosarcoma, stage and clinical group.

Risk groupType of rhabdomyosarcomaStageClinical group

low

embryonal

1

I, II or III

embryonal

2 or 3

I or II

intermediate

embryonal

2 or 3

III

alveolar

1, 2 or 3

I, II or III

high

embryonal or alveolar

4

IV

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