Rhabdomyosarcoma is a cancerous tumor that originates in the soft tissues of the body, including the muscles, tendons, and connective tissues. The most common sites for this tumor to be found include the head, neck, bladder, vagina, arms, legs, and trunk. Rhabdomyosarcoma can also be found in places where skeletal muscles are absent or very small, such as in the prostate, middle ear, and bile duct system. The cancer cells associated with this disease can spread (metastasize) to other areas of the body.
Embryonal rhabdomyosarcoma, the most common type, usually occurs in children under 6 years of age. Alveolar rhabdomyosarcoma occurs in older children and accounts for about 20 percent of all cases.
Rhabdomyosarcoma accounts for about 3 percent of childhood cancers. In the US, about 350 children are diagnosed with rhabdomyosarcoma each year. This disease affects people between the ages of 2 to 25 years of age, but can occur at any age. For unknown reasons, males are affected slightly more often than females.
It is believed that some rhabdomyosarcoma tumors begin developing in the fetus. Rhabdomyoblasts are the cells at the initial stages of development of an unborn baby. These cells will mature and develop into muscles. There has been much research into the gene structure of these rhabdomyoblasts and possible detection of a gene error that can produce the disease later in development.
Rhabdomyosarcomas usually have some type of chromosome abnormality in the cells of the tumor, which are responsible for the tumor formation. In children with an embryonal rhabdomyosarcoma, there is usually an abnormality of chromosome #11. In alveolar rhabdomyosarcoma, a rearrangement in the chromosome material between chromosomes #2 and #13 is usually present. This rearrangement changes the position and function of genes, causing a fusion of genes referred to as a "fusion transcript." Patients have an abnormal fusion transcript involving two genes known as PAX3 and FKHR. This important discovery has led to improvements in diagnosing rhabdomyosarcoma.
Rhabdomyosarcomas are also more common in children with neurofibromatosis or Li-Fraumeni syndrome, which are genetic disorders. Li-Fraumeni syndrome is a clustering of soft tissue cancers in a family, caused by mutations in a tumor suppressor gene called p53, which results in uncontrolled cell growth.
There has been no association between rhabdomyosarcoma and environmental exposures.
The following are the most common symptoms of rhabdomyosarcoma. However, each child may experience symptoms differently. Many symptoms depend on the size and the location of the tumor. Symptoms may not be present until the tumor is very large, especially if it is located deep in the muscle or in the stomach. Symptoms may include:
The symptoms of rhabdomyosarcoma may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.
In addition to a complete medical history and physical examination, diagnostic procedures for rhabdomyosarcoma may include:
Diagnosis involves staging and classifying the tumor, which is important in determining treatment options.
Staging is the process of finding out whether cancer has spread, and, if so, how far. There are various staging systems that are used for rhabdomyosarcoma. Always consult your child's physician for more information on staging. One method of staging is the TNM staging system. This system uses tumor (T), nodes (N), and metastases (M) to differentiate the disease by stages. This system evaluates the disease before surgery and classifies it by one of the four following stages:
Specific treatment for rhabdomyosarcoma will be determined by your child's physician based on:
Treatment may include (alone or in combination):
Prognosis greatly depends on:
As with any cancer, prognosis and long-term survival can vary greatly from child to child. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential if your child is diagnosed with rhabdomyosarcoma. Side effects of radiation and chemotherapy, as well as second malignancies, can occur in survivors of rhabdomyosarcoma.