Rhabdomyosarcoma is a malignant tumor developed from the skeletal muscle tissue. It is a malignant soft tissue tumor that develops from striated muscle cells. This is the most commontumor in children and adolescents. Rhabdomyosarcoma develop mainly at cephalic cavities (orbit, nose, sinuses, ears) or urogenital tract (bladder, prostate, vagina, spermatic cord). More rarely, they can form in muscle in the limbs.
The annual incidence of rhabdomyosarcoma is about 1 out of 170 000 individuals. In childrenless than 15 years, the annual incidence is estimated to be less than 1/245 000. The median age at diagnosis is 5 years.
Causes of Rhabdomyosarcoma
As in the case of most cancers, rhabdomyosarcoma occurs when some cells become abnormal, and then divide uncontrollably to eventually form a cancerous tumor. The cancer can be different types, depending on the characteristic of the cells. For instance, the tumor can be embryonal rhabdomyosarcoma because the tumor resembles muscle cells in the embryo.
Despite the advances in better understanding the mechanisms of cancer development, it is very difficult to accurately determine the causes of rhabdomyosarcoma. However, scientific studies have not shown that the environment, food, certain chemicals, family lifestyle of the child can play a role in the development. Psychological and emotional factors in the parents are also suspected.
However, most rhabdomyosarcomas present no family hereditary factors. In a family, thedisease occurs very often in isolation. There is no reason to perform tests in the parents,brothers and sisters of a child with rhabdomyosarcoma. But it seems in very exceptional cases,certain genetic defects may predispose a child to the development of rhabdomyosarcoma. This is the case of children suffering from Recklinghausen’s disease, Li-Fraumeni syndrome orneurofibromatosis type 1 (NF1).
Signs and Symptoms of Rhabdomyosarcoma
Signs and symptoms of rhabdomyosarcoma can be similar to symptoms of other medical conditions. In addition, they may vary greatly depending on the size, location and characteristic localized or metastatic tumor. It is, therefore, important to consult a health care professional for diagnosis before confirming anything.
In the general, rhabdomyosarcoma symptoms include the following:
Swelling or mass
Pain or tenderness in the affected area
Limping or other difficulty using the legs, feet, arms or hands
Diagnostic of Rhabdomyosarcoma
Rhabdomyosarcoma diagnosis is based on the positivity of muscle markers inimmunohistochemistry (IHC), a diagnostic procedure used to detect antigens (for instance proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues. The detection of the presence of translocation of the protein allows the health care provider to diagnose the alveolar forms. The differential diagnosis includes small round cell tumors such as lymphomas, neuroblastoma, Ewing’s sarcoma, and others. TheImmunohistochemical allows studying and distinguishing these tumors.
Rhabdomyosarcoma Treatment begins after the biopsy, usually with a first phase ofchemotherapy tailored to the child. This phase treatment usually lasts 12 weeks. This includeschemotherapy drugs: vincristine, ifosfamide, actinomycin D and doxorubicin. Local therapy mayinclude surgery when possible with more or less radiation therapy, depending on potential risks.Alveolar rhabdomyosarcomas have a higher risk and are routinely irradiated. They also receivemore intensive treatment than embryonal rhabdomyosarcomas
Sometimes the local procedure will be radiotherapy in the head and neck. Chemotherapy withthe same drugs, follow this local therapy with a total treatment that lasts 6 months. In some cases, the patient can be offered a complementary treatment for 6 months to a year with a less aggressive chemotherapy called maintenance treatment in order to help keep the cancer from coming back after it has disappeared.
When it comes to rhabdomyosarcomas, survival depends on the location of the tumor. Inlocalized tumors, it is greater than 80% for tumors of the orbit, of the bladder, vagina, andparatesticular region. It is between 60% and 70% for other localized tumors. Survival rates ofpatients with metastases at diagnosis is less, and among them, adolescents and patients withbone marrow metastases have a survival of less than 20%.