Definition and Overview
Rhabdomyosarcoma (RMS) is a type of sarcoma, a rare kind of cancer that grows in connective tissue or cells such as fat, tendons, cartilage, nerves, muscles, and blood vessels. RMS starts from cells that form the skeletal muscles (rhabdomyoblasts), and although it can develop in any part of the body, it is commonly found in the head, neck, urinary and reproductive organs, abdomen, and chest. It is the most common type of soft tissue sarcoma in children and accounts for 3% of all childhood cancers. Based on statistics, there are only less than 400 new cases of RMS in the United States every year and that the majority of those that are affected are under the age of five.
The three main types of rhabdomyosarcoma are:
Alveolar rhabdomyosarcoma cancer (ARMS) - ARMS is aggressive and grows quite fast. Thus, patients require immediate, intensive treatment. It is more common in older children or teenagers and usually starts in the legs, arms or torso.
Embryonal rhabdomyosarcoma (ERMS) - Commonly affects children below five years old and usually starts in the reproductive organs, head and neck area, and bladder.
Anaplastic rhabdomyosarcoma - The least common type that is more common in adults than children.
Causes of Condition
Although most RMS cases occur sporadically, up to 33% of patients are thought to have an underlying risk factor including rare familial cancer syndromes. These include:
Li-Fraumeni syndrome (LFS) - A rare inherited genetic disorder commonly caused by a gene mutation in the p53 tumour suppressor gene. This abnormality reduces the body’s ability to stop cell growth that results in the formation of cancerous tumours. Patients with LFS have an increased risk of developing different types of cancers including RMS, leukemia, and breast cancer, among others.
Beckwith-Wiedemann syndrome - A growth regulation disorder that increases the risk of childhood tumours as well as hypoglycemia and kidney abnormalities. The syndrome is related to changes in genes of chromosome 11 and can be passed from generation to generation in a family.
Costello’s syndrome - Signs of this disorder include skeletal abnormalities, weak muscle tone, and structural abnormality of the brain. Beginning in early childhood, patients with this disorder are at an increased risk of developing cancerous tumours including rhabdomyosarcoma.
Rhabdomyosarcoma symptoms may vary depending on the location and size of the cancerous tumour. Children with orbital RMS usually have swollen or bulging eyes while those with tumours in parameningeal sites often complain of nasal discharge, stuffy nose, and a mass at the back of the throat or in the nostril. If the tumour develops in the brain, patients will experience severe headaches and may also develop cranial neuropathies.
Other symptoms may include:
Painless tumour in the scrotum (paratesticular tumour)
Mass in the vagina
Blood in urine
Visible mass in the pelvis or abdomen
Bleeding in the rectum, vagina, nose or throat
Sinus infection symptoms
Rarely, patients also suffer from unexplained fevers, easy bruising, fatigue, and poor appetite.
Who to See and Types of Treatments Available
Rhabdomyosarcoma cancer is diagnosed using a number of tests. Doctors usually start by conducting a thorough physical exam and reviewing the patient’s medical history. These are usually followed by imaging tests, including:
Magnetic resonance imaging (MRI)
Positron emission tomography (PET) scan
Computed tomography (CT) scan
If a tumour is found, bone marrow aspiration and biopsy is performed. It involves inserting a hollow needle into the hipbone to collect a small amount of tissue to look for signs of cancer. Doctors may also perform a lumbar puncture to collect cerebrospinal fluid (CSF) around the spinal cord.
These tests provide enough information for doctors to make a diagnosis and determine the stage of rhabdomyosarcoma.
Stage I - Characterised by the presence of tumour in one of the following sites: eye or around the eye, bile ducts or gallbladder, head or neck, urethra, testes, ovary, vagina, or uterus.
Stage II - The patient has a tumour that is not larger than 5 centimetres in locations other than the sites mentioned above.
Stage III - Cancer has spread to nearby lymph nodes
Stage IV - Cancer has spread to distant organs such as bone, bone marrow or lung
Low-risk patients, or those with localised tumours, have a good rhabdomyosarcoma prognosis after treated with surgery with or without chemotherapy and radiation therapy. Patients who fall under this category are those with orbital tumours and those whose tumours are completely removed by surgery. In general, alveolar rhabdomyosarcoma prognosis can be as high as 80% if cancer has not yet spread.
Intermediate-risk patients or those with non-metastatic tumours are treated with a relatively more intensive therapy, which usually combines surgery, chemotherapy, and radiation therapy.
High-risk patients are treated with surgery and aggressive chemotherapy and radiation therapy. However, despite intensive treatment, the prognosis for these patients is usually poor. Under this category are:
Patients with metastatic alveolar RMS
Patients with metastatic embryonal RMS
Infants with metastatic embryonal RMS
Patients with metastatic extremity tumours
Rhabdomyosarcoma treatment causes side effects and results in complications in many cases. These include hair loss, fatigue, nausea, and increased susceptibility to infection.
Patients are also at risk of long-term side effects that can manifest months or years after successful treatment. These include:
Chronic sinus infection
An increased risk of secondary cancer – The use of radiation therapy and chemotherapy increases the risk of secondary cancer, most commonly leukemia and secondary sarcoma.
Damage to the heart
Problems with memory
Qualman SJ, Bowen J, Parham DM, Branton PA, Meyer WH. Protocol for the examination of specimens from patients (children and young adults) with rhabdomyosarcoma. Archives of Pathology and Laboratory Medicine 2003;127:1290-1297.
Breneman JC, Lyden E, Pappo AS. Prognostic factors and clinical outcomes in children and adolescents with metastatic rhabdomyosarcoma – A report from the Intergroup Rhabdomyosarcoma Study IV. Journal of Clinical Oncology 2003; 21:78-84.
Wiener ES, Anderson JR, Ojimba JI et al. Controversies in the management of paratesticular rhabdomyosarcoma: is staging retroperitoneal lymph node dissection necessary for adolescents with resected paratesticular rhabdomyosarcoma? Seminars in Pediatric Surgery 2001;10:146-152.