Rhabdomyosarcoma is a form of sarcoma - cancer of the bone, soft tissues, tendons and cartilage (connective tissue). Rhabdomyosarcoma begins in the skeletal or voluntary muscles, those that people can control. It is the most common form of sarcoma found in children and accounts for 5 to 8 percent of all childhood cancers. About 250 cases are diagnosed each year. After treatment, two-thirds of children diagnosed with the disease survive.
Under a microscope, rhabdomyosarcoma cells look like rhabdomyoblasts, which are found in the fetus and are supposed to develop into skeletal muscles.
About 40 percent of the time, the disease occurs in the head and neck, and nearly 30 percent of the time in the urinary or reproductive organs. It can also develop in the arms, legs and trunk. Rarely, rhabdomyosarcoma can also occur in the prostate, middle ear, and bile duct system.
Embryonal rhabdomyosarcoma (ER) is the most common form of the disease. Its cells resemble those of developing muscle in a six- to eight-week-old fetus. ER tends to affect infants and young children, and usually begins in the head and neck, bladder or vagina, and in or near the prostate and testicles. Five-year survival rates are 70 to 80 percent.
There are two additional subtypes of ER: spindled (containing spindle-shaped cells) and botryoid (grape-like clusters of tissue). The prognosis for either of these is usually better than for ordinary ER.
Alveolar rhabdomyosarcoma is another form of the disease. The malignant cells form alveoli (hollow spaces) in the muscles. Alveolar rhabdomyosarcoma cells resemble normal muscle cells found in a fetus of 10 weeks. The disease affects older children and teenagers, and usually occurs in the large muscles of the arms, legs and trunk. Alveolar cancer is more aggressive than embryonal cancer. Five-year survival is slightly more than 50 percent.
Copyright © 2000 Oncology.com, Inc. All rights reserved.
