Clinical groups
The clinical group is based on the extent of the disease and how completely it is removed during initial surgery. Briefly, 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) and there is no evidence of any tumor left behind after 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 it 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 either around the edges of the removed specimen or in the lymph nodes. In both cases, as much of the cancer has been removed as possible. Group II has 3 subgroups:
Group IIA: In this group, 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. It has not spread to nearby lymph nodes or elsewhere.
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
With the information about the type of rhabdomyosarcoma, the clinical group, and the TNM stage, doctors then classify patients into 3 risk categories . These risk groups help doctors decide how aggressive treatment should be.
Clinical risk groups are defined based on what we have learned from previous research and the outcomes of patients. The risk groups discussed below 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
Below are general survival statistics based on risk groups. These numbers come from large clinical trials treating children with rhabdomyosarcoma in the 1980s and 1990s. 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.
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 50% to about 70%. 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 all 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.
