The Hugs for Harper Endowment mission is to find a cure for Pediatric Soft Tissue Cell Cancer. Specifically, Rhabdomyosarcoma.
Browse through the tabs below to learn more.
What is rhabdomyosarcoma?
Sarcomas are cancers that develop from connective tissues in the body, such as muscles, fat, bones, membranes that line the joints, or blood vessels. There are many types of sarcomas. Rhabdomyosarcoma (RMS) is a cancer made up of cells that normally develop into skeletal muscles. The body has 3 main types of muscles.
- Skeletal (voluntary) muscles are muscles that we control to move parts of our body.
- Smooth muscle is the main type of muscle in internal organs (except for the heart). For example, smooth muscles in the intestines push food along as it is digested. We do not control this movement.
- Cardiac muscle is the main muscle type in the heart.
About 7 weeks into the development of an embryo, cells called rhabdomyoblasts (which will eventually form skeletal muscles) begin to form. These are the cells that can develop into rhabdomyosarcoma. Because this is a cancer of embryonal cells, it is much more common in children, although it does sometimes occur in adults.
We think of our skeletal muscles as being mainly in our arms and legs, but these skeletal muscle cancers can start nearly anywhere in the body. Common sites include:
- Head and neck (near the eye, inside the nasal sinuses or throat, or near the spine in the neck)
- Urinary and reproductive organs (bladder, prostate gland, or any of the female organs)
- Arms and legs
- Trunk (chest and abdomen)
Rhabdomyosarcomas can even start in some parts of the body that don’t normally have skeletal muscle.
Types of rhabdomyosarcoma
There are 2 main types of rhabdomyosarcomas, along with some less common types.
Embryonal rhabdomyosarcoma (ERMS) is the most common type of rhabdomyosarcoma. It usually affects infants and young children. The cells of ERMS look like the developing muscle cells of a 6- to 8-week-old embryo. ERMS tends to occur in the head and neck area, bladder, vagina, or in or around the prostate and testicles.
Two subtypes of ERMS, botryoid and spindle cell rhabdomyosarcomas, tend to have a better prognosis (outlook) than the more common form of ERMS.
Alveolar rhabdomyosarcoma (ARMS) typically affects older children or teens and occurs more often in large muscles of the trunk, arms, and legs. ARMS cells look like the normal muscle cells seen in a 10-week-old fetus. ARMS tends to grow faster than ERMS and usually requires more intensive treatment.
Anaplastic rhabdomyosarcoma and undifferentiated sarcoma
Anaplastic rhabdomyosarcoma (formerly called pleomorphic rhabdomyosarcoma) is an uncommon type that occurs in adults but is very rare in children.
Some doctors also group undifferentiated sarcomas with the rhabdomyosarcomas. Doctors can tell that these cancers are sarcomas using lab tests, but the cells don’t have any features that help classify them further.
Both of these uncommon cancers tend to grow quickly and usually require intensive treatment.
Rhabdomyosarcoma in adults
Most rhabdomyosarcomas occur in children, but they can also occur in adults. Adults are more likely to have faster-growing types of rhabdomyosarcoma and to have them in parts of the body that are harder to treat. Because of this, rhabdomyosarcomas in adults are often harder to treat effectively.
What are the key statistics about rhabdomyosarcoma?
Rhabdomyosarcoma (RMS) accounts for about 3% of all childhood cancers. About 350 new cases of RMS occur each year in the United States. The number of new cases has not changed much over the past few decades.
Most rhabdomyosarcomas are diagnosed in children and teens. About 2 of 3 of all rhabdomyosarcomas are diagnosed in children younger than 10 years old. These tumors are usually embryonal rhabdomyosarcomas (ERMS) and occur in the head and neck area or in the genital and urinary tracts. Alveolar rhabdomyosarcoma (ARMS) affects all age groups and is found more often in the arms, legs, or trunk.
RMS is slightly more common in boys than in girls. No particular race or ethnic group seems to have an unusually high rate of RMS.
The prognosis (outlook) for people with RMS depends on many factors, including the location, histologic type, and size of the tumor, the results of surgery, and whether the cancer has metastasized (spread). Children aged 1 to 9 tend to have a better outlook than infants or older children or adults. Statistics related to survival are discussed in the section, “Survival rates for rhabdomyosarcoma by risk group”
Do we know what causes rhabdomyosarcoma?
We still do not know what causes most cases of rhabdomyosarcoma (RMS), but researchers are starting to understand how certain changes in DNA can cause normal cells to become cancerous. DNA is the chemical in each of our cells that makes up our genes – the instructions for how our cells function. It is packaged in chromosomes (long strands of DNA in each cell). We normally have 23 pairs of chromosomes in each cell (one set of chromosomes comes from each parent). We usually look like our parents because they are the source of our DNA. But DNA affects more than how we look.
Some genes are instructions for controlling when our cells grow, divide into new cells, and die. Certain genes that help cells grow and divide are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA changes that “turn on” oncogenes or “turn off” tumor suppressor genes.
For example, people with Li-Fraumeni syndrome have changes in the TP53 tumor suppressor gene that cause it to make a defective p53 protein. The p53 protein normally causes cells with DNA damage to either pause and repair that damage or, if repair is not possible, to self-destruct. When p53 is not working, cells with DNA damage continue to divide, causing further defects in other genes that control cell growth and development. This may lead to cancer.
Certain genes in a cell can be activated when bits of DNA are switched from one chromosome to another. This type of change, called a translocation, can happen when a cell is dividing into 2 new cells. This seems to be the cause of most cases of alveolar rhabdomyosarcoma (ARMS). In these cancers, a small piece of chromosome 2 (or, less often, chromosome 1) ends up on chromosome 13. This moves a gene called PAX3 (or PAX7 if it’s chromosome 1) right next to a gene called FOXO1. The PAX genes play an important role in causing cells to grow while an embryo’s muscle tissue is being formed, but these genes usually shut down once they’re no longer needed. The normal function of the FOXO1 gene is to activate other genes. Moving them together likely activates the PAX genes, which may be what leads to the tumor forming.
Research suggests that embryonal rhabdomyosarcoma (ERMS) develops in a different way. Cells of this tumor have lost a small piece of chromosome 11 that came from the mother, and it has been replaced by a second copy of that part of the chromosome from the father. This seems to cause the IGF2 gene on chromosome 11 to be overactive. The IGF2 gene codes for a protein that may cause these tumor cells to grow.
Changes in several different genes are usually needed for normal cells to become cancer cells. Scientists have found other gene changes that set some RMS cells apart from normal cells, but there are likely others that have not yet been found.
Researchers now understand many of the gene changes that may lead to RMS, but it’s still not clear what might cause these changes. Some gene changes may be inherited. Others may just be a random event that sometimes happens inside a cell, without having an external cause. There are no known lifestyle-related or environmental causes of RMS, so it is important to know that there is
Survival rates for rhabdomyosarcoma by risk group
Survival rates are often used by doctors as a standard way of discussing a person’s prognosis (outlook). Some people may want to know the survival statistics for those in similar situations, while others may not find the numbers helpful, or may even not want to know them. If you would rather not read about the survival rates, skip to the next section, “How is rhabdomyosarcoma treated?”
The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is diagnosed. Of course, many people live much longer than 5 years (and many are cured).
In order to get 5-year survival rates, doctors have to look at people who were treated at least 5 years ago. Improvements in treatment since then may result in a more favorable outlook for patients now being diagnosed with RMS.
Survival rates are often based on previous outcomes of large numbers of people who had the disease, but they cannot predict what will happen in any particular person’s case. The risk group of a person’s cancer is important in estimating their outlook. But many other factors may also affect a person’s outlook, such as their age, the location of the tumor, certain gene changes in the cancer cells, and how well the cancer responds to treatment.
Here are general survival statistics based on risk groups. These numbers come from large clinical trials treating children with RMS in the 1980s and 1990s.
Overall, the 5-year survival rate for children in the low-risk group is over 90%. Most of these children will be cured.
For those in the intermediate-risk group, the 5-year survival rates range from about 60% to about 80%. The rate varies somewhat based on tumor location, stage, and the age of the child (with children aged 1 to 9 tending to do better than older or younger children).
If the cancer has spread widely, the 5-year survival rate is generally around 20% to 40%. 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 (ERMS) and limited spread (to only 1 or 2 distant sites) have a higher 5-year survival rate.
Even when taking risk groups and other factors into account, survival rates are at best rough estimates. Your child’s doctor can tell you how well these numbers may apply, as he or she is familiar with the aspects of your particular situation.
nothing these children or their parents could have done to prevent these cancers.
Used with permission from the American Cancer Society