Among all childhood cancers, there are only 350 cases of Rhabdomyosarcoma diagnosed per year. The 5 year survival rate, though predicated on many factors has not realized a significant improvement in the high risk group remaining at approximately 19%
What is Rhabdomyosarcoma?
Rhabdomyosarcoma (RMS) is a rare soft tissue sarcoma that forms in muscle and connective tissue. It can occur at any age, but generally affects children, teens and young adults. It is the most common soft tissue sarcoma in children.
There are between 350 to 400 newly diagnosed cases per year.
Embryonal- peak incidence 0-4 years of age and accounts for 57% of patients.
Alveolar- incidence is constant between 0-19 years of age and accounts for 23%of patients.
Anaplastic- accounts for 2% of children.
Pleomorphic- generally seen in adults.
Sclerosing- only recently identified.
Primary Sites of Location:
Head and neck-25%
Genital and urologic-22%
Most cases occur sporadically and therefor have no associated risk factors. However there are a few genetic disorders that carry mutations that can be associated with this cancer.
The most common presentation is a lump or swelling on the body. However, depending on the location of the tumor, there may be initial clinical symptoms associated with the location.
A primary tumor located in the head and neck may cause obstruction or discharge from the nose or throat. Tumors near the eye can cause swelling or protrusion near the orbit.
A tumor in the bladder may present with blood in the urine, likewise, tumors in the vagina will cause vaginal discharge or bleeding.
A tumor in the abdomen may present with pain and constipation.
Diagnosis of RMS:
Biopsy of the tumor is the definitive method, but in order to stage the tumor and determine optimum therapy, a multitude of blood tests and scans will be obtained to include: chest x-ray, ultrasound, CT and MRI scans, blood tests and bone marrow aspirates.
Once the size, extent (localized vs. metastatic) and tumor subtype have been determined, the subsequent therapy will include surgical excision, chemotherapy, radiation therapy, or a combination of these modalities.
Prognosis is predicated on a multitude of factors. Localized lesions with complete resection of the tumor have the best 5 year prognosis. There is an association between age of the patient at the time of diagnosis, along with the location site of the original tumor and the overall prognosis.
Many patients will initially achieve a good response from the chemotherapy within a 3-6 month time frame. The 1st intergroup rhabdomyosarcoma study in 1972 found ¾ of the patients with metastatic RMS had a 50% complete or 25% partial response within 15 weeks. The difficulty remains with preventing recurrence of occult disease. Most relapses occur within 24 months of diagnosis. Moreover, there has been no significant improvement in long term survival for patients with metastatic disease. (1)
Sarcoma (2001) 5, 9-15.