Once the type of tumor has been identified, doctors need to assess, as accurately as possible, how much of it there is and where it has spread. The answers to "how much" and "where" are expressed in a kind of shorthand known as staging.

The outlook (prognosis) for people with cancer depends, to a large extent, on the cancer's stage. The stage of a cancer is one of the most important factors in choosing treatment.

Your child's doctors will use the results of the imaging tests and biopsies (described in "How is rhabdomyosarcoma diagnosed?") and the direct examination of the organs during surgery to determine how far the cancer has spread. If there is any doubt about the extent of the cancer, more biopsies may be done on tissue at the edge of the tumor, nearby lymph nodes, and any suspicious lumps in other parts of the body.

Staging for rhabdomyosarcoma is fairly complex. Doctors first determine 3 key pieces of information:

• the type of rhabdomyosarcoma (embryonal or alveolar)
• the clinical group
• the TNM stage

These factors are then used to divide patients into risk groups, which then are used to determine the best treatment options.

Clinical groups

The clinical group is based on the extent of the disease and how completely it is removed during initial surgery. The groups are defined as follows.

Group I

This group includes children with localized disease (the cancer has not spread to nearby lymph nodes or to distant sites in the body) that is completely removed by surgery. Group I has 2 subgroups:

Group IA: Children in this group had a tumor that was still confined to the muscle or organ where it started and was completely removed by surgery. It had not spread to nearby lymph nodes or distant sites.

Group IB: Children in this group had a tumor that had grown beyond the muscle or organ where it started and into nearby structures, but it was completely removed by surgery. It had not spread to nearby lymph nodes or distant sites.

About 15% of rhabdomyosarcoma patients are in group I.

Group II

This group includes children who have had tumors that have been removed by surgery, but cancer has been found around the edges of the removed specimen, in the lymph nodes or in both places. In all cases, as much of the cancer has been removed as possible. Group II has 3 subgroups:

Group IIA: In this group, the cancer has not spread to nearby lymph nodes or elsewhere. The surgeon has removed all the cancer that could be seen, but the pathologist has found cancer at the edge of the removed specimen, which means that there is a small amount of cancer left behind.

Group IIB: In this group, the cancer has spread to nearby lymph nodes, but all of the cancer has been removed by surgery.

Group IIC: In this group, the cancer has spread to nearby lymph nodes. The surgeon has removed all the cancer that could be seen (including in the lymph nodes), but the pathologist has found cancer at the edge of the removed specimen, which means that there is a small amount of cancer left behind.

About 20% of patients are in group II.

Group III

These children have tumors that cannot be completely removed, leaving some tumor behind that can be seen with the naked eye. The tumor may have spread to nearby lymph nodes, but there is no sign that it has spread to distant organs. Group III has 2 subgroups:

Group IIIA: The tumor cannot be completely removed by surgery, and only a biopsy of the tumor has been done.

Group IIIB: The tumor cannot be completely removed, but surgery has removed at least half of the tumor.

This group accounts for about 50% of patients with rhabdomyosarcoma.

Group IV

These children have evidence of distant spread at the time of diagnosis to places such as the lungs, liver, bones, bone marrow, or to distant muscles or lymph nodes.

This group contains about 15% of children with rhabdomyosarcoma.

The TNM stage

The TNM stage doesn't depend on the results of surgery, but on the type and size of the tumor, its invasion of the lymph nodes and distant organs, and where it starts. It is based on 3 key pieces of information:

• T: the characteristics of the tumor
• N: whether the cancer has spread to nearby lymph nodes
• M: whether it has metastasized (spread) to distant parts of the body

These factors are combined to determine an overall stage:

Stage 1: The tumor started in a favorable area:

• the orbit (area near the eye)
• the head and neck area, except for parameningeal sites (next to the membranes covering the brain)
• a genital or urinary site, except the bladder or prostate
• biliary tract (tubes leading from the liver to the intestines)

The tumor can be any size. It may have grown into nearby areas and/or spread to nearby lymph nodes, but it has not spread to distant sites.

Stage 2: The tumor started in an unfavorable site:

• the bladder or prostate
• an arm or leg
• a parameningeal site (next to the membranes covering the brain)
• any other site not mentioned in stage 1

The tumor is smaller than 5 cm (about 2 inches) across and there is no evidence that it has spread to nearby lymph nodes or distant sites.

Stage 3: The tumor started in an unfavorable site:

• the bladder or prostate
• an arm or leg
• a parameningeal site (next to the membranes covering the brain)
• any other site not mentioned in stage 1

One of the following applies:

• the tumor is smaller than 5 cm across but has spread to nearby lymph nodes
• the tumor is larger than 5 cm across and may or may not have spread to nearby lymph nodes

In either case, the cancer has not spread to distant sites.

Stage 4: The tumor can have started at any site and can be of any size. It has spread to distant sites such as the lungs, liver, bones, or bone marrow.

Risk groups

Using the information about the type of rhabdomyosarcoma, the clinical group, the TNM stage, and the child's age, doctors classify patients into 3 risk groups. Information about risk groups helps doctors decide how aggressive treatment should be.

Clinical risk groups are defined based on what has been learned from previous research on patients' outcomes. The risk groups discussed here are based on the most current information, but these may change in the future as safer and more effective treatments are developed.

Low-risk group

This group includes:

• children with TNM stage 1 embryonal rhabdomyosarcomas (ERMS) that fall into clinical groups I, II, or III
• children with stage 2 or 3 ERMS who are in clinical groups I or II

Intermediate-risk group

This group includes:

• children with stage 2 or 3 ERMS who are in clinical group III
• children with stage 4 ERMS (any group) who are younger than 10 years old
• children with alveolar rhabdomyosarcoma (ARMS) that has not spread to distant sites (stage 1, 2, or 3)

High-risk group

This group includes:

• children with widespread (stage 4) ARMS
• children with widespread (stage 4) ERMS who are 10 years old or older

Five-year survival rates by risk group

Survival statistics can be complex, and there are some important points to note about these numbers:

• The 5-year survival rate refers to the percentage of patients who live at least 5 years after being diagnosed. They are used to produce a standard way of discussing prognosis (the outlook for recovery and survival). Of course, many people live much longer than 5 years.

• These numbers are among the most current we have available, but they represent children who were first diagnosed and treated many years ago. Improvements in treatment since then mean that the survival rates for those now being diagnosed with these cancers may be higher.

• Although survival statistics can sometimes be useful as a general guide, they may not accurately represent any one child's prognosis. A number of other factors, including tumor characteristics (such as where it started, the tumor type, and where and how far it has spread) and a child's age, also affect outlook. Your child's doctor is likely to be a good source as to whether these numbers may apply to your child, as he or she is familiar with the aspects of the particular situation.

Here are general survival statistics based on risk groups. These numbers come from large clinical trials treating children with rhabdomyosarcoma in the 1980s and 1990s.

Low-risk group

Overall, the 5-year survival rate for children in the low risk group is over 90%. Most of these children will be cured.

Intermediate-risk group

For those in the intermediate risk group, the 5-year survival rates range from about 60% to about 80%. The rate varies somewhat by tumor location, stage, and the age of the child.

High-risk group

If the cancer has spread widely, the 5-year survival rate is generally around 20% to 25%. Again, it's important to note that other factors, such as the age of the patient and the site and type of tumor will affect these numbers. For example, children with embryonal rhabdomyosarcoma and limited spread (to only 1 or 2 distant sites) have a higher 5-year survival rate.

Last Medical Review: 09/08/2009
Last Revised: 09/08/2009