Rhabdomyosarcoma (RMS) is the most common childhood soft tissue sarcoma. Approximately 350 children are diagnosed with RMS in the United States each year. Two-thirds of these cases are diagnosed in children younger than age 5. The disease has a slightly higher incidence in males compared with females. Black children have a slightly higher incidence than white children.

Description

RMS is a malignant soft tissue tumor of primitive muscle cells called rhabdomyoblasts. Instead of maturing into muscle cells, the rhabdomyoblasts grow out of control. Because muscles are located throughout the body, the tumors can appear at numerous locations. The four sites where RMS is most commonly found are the head and neck, genitourinary tract, extremities, and chest and lungs.

Treatment

Treatment depends on the location of the tumor, whether it has spread, its histology (meaning how it looks under a microscope), and its molecular genetics. Prior to the 1950s, the only treatment for RMS was surgical removal of the tumor. Many tumors were not completely removable, and up to 18 percent of children had metastatic disease at diagnosis. The addition of radiation in the 1950s and chemotherapy in the 1960s dramatically improved survival rates for children and teens with RMS.

Surgery

All children and teens with RMS have surgery, either to remove all or part of the primary tumor, or to perform a biopsy to reach a diagnosis. Surgery is used as early as possible in the course of treatment and is the quickest method to reduce the amount of the disease. However, complete removal may not be possible, particularly if the mass is located near vital blood vessels, if it deeply invades surrounding normal tissue, or if there are functional or cosmetic reasons for avoiding such a procedure.

During surgery the doctor removes as much of the tumor as possible and then samples surrounding tissues that are later examined by a pathologist. The pathologist determines whether the entire tumor has been removed or if some cells remain behind.

Second-look surgical procedures are sometimes done after chemotherapy to remove any remaining residual disease and determine whether remission has been reached. This is especially important for choosing appropriate further treatment, such as the amount of radiation to be given. Approximately 10 percent of newly diagnosed children have tumors that can be completely removed. In most cases, residual disease is present. For this reason, chemotherapy is used in all treatment protocols, and radiation is used in most.

Chemotherapy

Chemotherapy is given to all children and teens with RMS to destroy any cancer not removed surgically. Giving several anticancer drugs in combination has markedly improved the survival rate for this disease. The most commonly used drugs include cyclophosphamide (Cytoxan ^® ), vincristine (Oncovin ^® ), ifosfamide (Ifex ^® ), etoposide (VP-16 or Vepesid ^® ), doxorubicin (Adriamycin ^® ), and dactinomycin (Cosmegen ^® ).

Radiation

Radiotherapy is an important tool used to treat children and teens with RMS. Generally, those with stages I and II disease do not receive radiation therapy if their tumors can be completely removed. However, the need for radiation also depends on the histology of the tumor. Current protocols give patients with residual disease 3000 to 5100 cGy of external beam radiation although, in the past, higher doses of radiation were given. New radiation methods such as intensity-modulated radiation therapy (IMRT), fractionated stereotactic radiation therapy, and proton beam radiation are sometimes used for patients with head and neck RMS.

Most often, radiation is given approximately 1 to 3 months after chemotherapy has begun. However, children with tumors in the skull, meninges, or spinal cord may start radiation therapy soon after diagnosis.

Investigational use of brachytherapy (i.e., implanting radioactive seeds for continuous low-level administration of radiation) is ongoing for children and teens with RMS, especially those with small tumors in critical areas such as the head, prostate, bladder, or vagina.

Late effects

This section briefly outlines some common and uncommon late effects from treatment. Remember that you may develop none, one, or several of these problems in the months or years after treatment ends.

Loss of tissue and scarring. One universal late effect from surgery for RMS is loss of tissue and a scar where the tumor was removed. In cases where the surgeon performed a radical lymph node dissection, lymphedema (i.e., backup of lymph in extremities) can result. For more information, see Chapter 16 .

Altered growth. The growing bodies of young children given high doses of radiation develop an altered appearance in the areas radiated, because growth is affected. Because RMS can appear in different areas of the body, refer to the chapters about those specific areas for detailed information about late effects. For instance, high doses of radiation to the orbit and surrounding tissues causes asymmetry in growth and development in the bones around the eye. One orbit will be smaller than the other. Cataracts and other side effects can also develop after radiation. For more information, see Chapter 10 .

Bladder and kidney problems. In the past, children with tumors in the genitourinary area had the bladder removed in the initial surgery. The resulting permanent ileal conduit (i.e., diversion of the flow of urine to a bag outside the body) could develop many complications over time. Now, the bladder is only removed if the cancer remains after chemotherapy and radiation.

Radiation of the abdomen and/or pelvis that exceeds 2300 cGy can cause chronic nephritis (inflammation of the kidney) and a host of related kidney complications including fatigue, anemia, high blood pressure, hyperuricemia (excess uric acid in the blood), and gout. These problems can develop months or years after radiation treatment. Radiation of the abdomen can also cause fibrosis that obstructs the ureters. For more information about these problems, see Chapter 14 .

Problems after lymph node removal. Radical removal of the lymph nodes in the area of the testes or prostate can result in retrograde ejaculation or bowel obstruction. Problems with ejaculation and decreased sperm production are common in males who had RMS in or near the genitals. For more information, see Chapter 9 .

Ovarian failure. Radiation to the abdomen can cause ovarian failure in some female survivors. For more information, see Chapter 9 .

Curvature of the spine. Abdominal radiation at higher doses can also cause curvature of the back. For more information, see Chapter 17 .

Learning disabilities. Cranial radiation and intrathecal chemotherapy used to treat children with parameningeal RMS (in the membranes surrounding the spinal cord and brain) can cause cognitive problems. The severity of the damage depends on the child’s treatment, age, and sex, with younger children being more at risk than older children or teens. Learning disabilities can develop years after treatment ends. Typically, problems develop in the areas of mathematics, memory, spatial relationships, problem solving, planning, organization, attention span, concentration skills, and social skills. For more information, see Chapter 8 .

Heart problems. Heart problems can occur months or years after treatment with anthracyclines (i.e., doxorubicin, idarubicin, or daunorubicin), high-dose cyclophosphamide, or chest radiation. Symptoms include shortness of breath, fatigue, wheezing, anxiety, poor exercise tolerance, rapid heartbeat, and irregular heartbeat. Few survivors develop this late effect, but regular checkups are crucial. Survivors often have no symptoms, but problems may be found on cardiac tests such as echocardiograms, electrocardiograms (EKGs), and Holter monitors. For more information, see Chapter 12 .

Hepatitis C. Infection with the hepatitis C virus can develop in survivors who had blood transfusions prior to July 1992. For more information, see Chapter 15 .

Uncommon late effects. Children and teens who receive radiation have a slight risk of developing a second cancer. Those treated with VP-16 have a small chance of developing a second leukemia within 3 to 5 years of treatment. For more information, see Chapter 19 .