Rhabdomyosarcomas
What are the types of rhabdomyosarcoma? All the information about this condition: types, causes, symptoms, and treatment.
Symptoms and Causes
A rhabdomyosarcoma is a type of soft tissue sarcoma characterized by the abnormal and uncontrolled growth of striated skeletal muscle cells, which are the voluntary muscles attached to bones. It is a fast-growing cancer that can develop anywhere in the body, although it most commonly occurs in the head and neck, urinary tract, genitals, and limbs.
This type of tumor is very rare and primarily affects children under the age of seven, although it can also appear in adolescents and adults.
Symptoms
The symptoms of rhabdomyosarcoma vary depending on the location of the sarcoma:
- Rhabdomyosarcoma in the head or neck:
- Headache
- Tearing
- Eye pain
- Eye protrusion
- Nasal congestion
- Voice changes
- Nasal discharge with pus and mucus
- Rhabdomyosarcoma in the genitourinary system:
- Abdominal pain
- Palpable abdominal mass
- Difficulty urinating and defecating
- Presence of blood in the urine
- Vaginal discharge with mucus and blood
- Polyp-like mass protruding from the vagina
- Rhabdomyosarcoma in the limbs:
- Hard, poorly defined masses
Causes
The abnormal cell growth that leads to tumor formation is due to genetic alterations that occur in the cells and affect their normal growth and division process. The origin of these alterations is unclear, although hereditary factors may contribute.
Based on the specific genetic alterations that cause the cancer, four types of rhabdomyosarcoma are identified:
- Embryonal rhabdomyosarcoma: the most common type. It is caused by the loss of one copy of chromosome 11p15.
- Alveolar rhabdomyosarcoma: caused by the fusion of the FOXO1 gene with the PAX3 or PAX7 genes. It is more common in adolescents.
- Spindle cell or sclerosing rhabdomyosarcoma: in children, it is due to gene rearrangements in the VGLL2 and NCOA2 genes. In adults, it is linked to MYOD1 gene variants.
- Pleomorphic rhabdomyosarcoma: the rarest type. It is characterized by complex karyotypes and unbalanced numerical and structural chromosomal changes.
Risk Factors
The presence of certain congenital genetic conditions increases the risk of developing rhabdomyosarcoma:
- Li-Fraumeni syndrome
- Neurofibromatosis type 1
- Beckwith-Wiedemann syndrome
- Costello syndrome
- Noonan syndrome
- DICER1 syndrome
Complications
Rhabdomyosarcoma can spread to other parts of the body through tissues, the bloodstream, or the lymphatic system. This process, known as metastasis, complicates treatment and reduces the chances of recovery. Rhabdomyosarcoma typically spreads to the lungs, bones, bone marrow, and lymph nodes.
Prevention
Rhabdomyosarcoma cannot be prevented.
What specialist treats rhabdomyosarcoma?
Rhabdomyosarcomas are diagnosed and treated by medical and radiation oncologists, as well as cardiovascular or general surgeons.
Diagnosis
After evaluating the symptoms and medical history, the following tests are performed to diagnose rhabdomyosarcoma:
- Computed tomography (CT) scan: detailed X-ray images are taken to assess the location and size of the tumor.
- Magnetic resonance imaging (MRI): images are produced using magnets and radio waves. It provides greater precision and definition for tumors located in the head and neck.
- Biopsy: a sample of the affected tissue is taken and analyzed in a lab to confirm the presence of cancer. The sample may be obtained by needle aspiration or surgery if a larger sample is needed.
Once rhabdomyosarcoma is confirmed, the presence of metastasis is assessed:
- Chest CT scan to detect pulmonary involvement.
- Positron emission tomography (PET): a small amount of radioactive glucose is injected into a blood vessel. Cancer cells absorb more glucose than healthy ones, so they appear brighter in the images.
- Bone scan: to check for the presence of cancerous cells in the bones, a radioactive material is injected into a vein. It accumulates in bones affected by cancer and can be detected with a scanner.
- Bilateral bone marrow biopsy: a sample of bone marrow, blood, and a small piece of bone is taken to check for the presence of cancer. The sample is extracted from the bones of both hips.
Treatment
Rhabdomyosarcoma treatment usually involves a combination of three approaches:
- Surgical excision: the tumor and part of the surrounding tissue are removed. In most cases, complete removal is not possible. Surgical treatment is also discouraged if it could cause organ damage or dysfunction.
- Radiation therapy: high-energy beams are directed at the affected area to destroy cancer cells. It is used to eliminate large tumors or those near vital organs when surgery is not feasible, or for residual tumors after surgery.
- External radiation therapy: radiation is delivered from a machine directed at the affected area.
- Internal radiation therapy (brachytherapy): radioactive material is placed directly in or near the tumor through a catheter.
- Chemotherapy: various drugs are administered to destroy or inhibit the proliferation of cancer cells. Chemotherapy is given to all rhabdomyosarcoma patients, regardless of risk level, to reduce the likelihood of cancer recurrence. It may also be used before surgery to shrink the tumor and facilitate its removal.
