Understand Childhood Cancers and Blood Disorders
Sarcomas are tumors that arise from connective tissue or connective tissue precursors. These include various tumors of muscle cells such as rhabdomyosarcoma (derived from skeletal or voluntary muscle) and leimyosarcoma (derived from smooth or involuntary muscle.) They may also arise from cells destined to be bones (osteogenic and Ewing's Sarcomas) or fibrous tissues such as cartilage. These are usually highly malignant tumors which grow quickly. Rhabdomyosarcoma along with bone tumors are the most common types of childhood sarcomas.
and account for approximately 5% of the cases of childhood cancers. The disease is more likely to occur in preadolescent children (peak incidence 1-5 years) compared with adolescents. Almost 3/4 of cases are diagnosed before ten years of age. Bone tumors are discussed elsewhere and we will focus on rhabdomyosarcomas.
Almost all cases of rhabdomyosarcoma occur sporadically with no recognized predisposing factors but a small percentage may be associated with rare genetic disorders. Examples of these include neurofibromatosis or the Li-Fraumeni cancer susceptibility syndrome.
Clinical manifestations of childhood sarcomas vary with the age of the patient, the site and size of the tumor in addition to the extent (or stage) of the primary tumor. Some common sites for these tumors include the pelvis, head and neck including the orbit. These tumors may also occur on the trunk, chest wall or extremities. A common symptom of rhabdomyosarcoma is the appearance of a tumor or mass that can be seen or felt that will not necessarily be painful. Abnormal bleeding such as from the rectum, vagina, nose or throat may also be reported. Pain, weakness, numbness, tingling, or difficulty moving the affected area as a result of nerve compression. Prominence or protrusion of an eye or a drooping eyelid may be an indication of a tumor in the area. These symptoms are not specific for rhabdomyosarcoma may be due to other diseases. Symptoms usually will become more apparent as the tumor grows. Other symptoms not mentioned here may also suggest the possibility of a rhabdomyosarcoma. To establish this diagnosis, a child will typically undergo a variety of imaging studies which may include CT or MRI scans, x-ray or ultrasound tests.
Many pediatric patients with rhabdomyosarcoma will have localized disease at diagnosis and will benefit from combined modality therapy which includes surgery to remove as much of the tumor as possible, chemotherapy treatments and radiation therapy. Effective chemotherapy drugs have been employed by pediatric oncologists for many years. Chemotherapy drugs which may be prescribed include Vincristine, Adriamycin, Actinomycin-D, Cyclophosphamide, Cisplatin, Ifosfamide, Etoposide or Carboplatinum. These drugs are all given intravenously through a central venous catheter that is place by a surgeon in the child's chest. These small catheters allow children to more easily receive chemotherapy treatments and transfusions without the need for the painful insertion of a peripheral intravenous line. Central venous catheters (Mediports) also allow for easy blood sampling. After successfully completing a treatment course, more than 70% of patients who presented with localized disease will be cured of their cancer. When patients with metastatic disease at diagnosis are included, the overall survival for children with this disease drops to about 50%. Late disease relapses are not common after five years of disease-free survival, with less than 10% of patients experiencing such relapses. As might be anticipated, relapses are more common for patients who have very large tumors or tumor spread at diagnosis.
Treatment for rhabdomyosarcoma may occasionally be associated with long term adverse effects. Possibilities include thyroid, kidney, liver, gastrointestinal or pulmonary problems as well as the possibility of a second malignancy. Because of these concerns, long term follow up by a competent pediatric oncology team is extremely important.