Table 5. Radiation Therapy (RT) Dose According to Rhabdomyosarcoma Group, Histology, and Site of Disease (Children's Oncology Group [COG]) continued...
The IRS-IV trial included a randomized study that reported the administration of RT twice a day, 6 to 8 hours apart, at 1.1 Gy per dose (hyperfractionated schedule), 5 days per week, was feasible but difficult to accomplish in small children who required sedation twice daily. Patients with localized, gross residual tumors were randomly assigned to receive conventional, once-daily RT (total dose of 50.4 Gy) versus the twice-daily hyperfractionated schedule (total dose of 59.4 Gy). There was no demonstrated advantage in terms of local control. Conventional RT remains the standard for treating patients who have rhabdomyosarcoma with gross residual disease.
Brachytherapy, using either intracavitary or interstitial implants, is another method of local control and has been used in selected situations for children with rhabdomyosarcoma, especially those with primary tumors at vaginal or vulvar sites [28,29,30,31,32] and selected bladder/prostate sites.[Level of evidence: 3iiiA] In small series from one or two institutions, this treatment approach was associated with a high survival rate and with retention of a functional organ or tissue in most patients.[29,34] Other sites, especially head and neck, have also been treated with brachytherapy. Patients with initial Group III disease, who subsequently have microscopic residual disease following chemotherapy with or without delayed surgery are likely to achieve local control with RT at doses of 40 Gy or more.
Very young children (aged ≤36 months) diagnosed with rhabdomyosarcoma pose a therapeutic challenge because of their increased risk for treatment-related morbidity. As suggested above, in older children, reduced radiation doses may be appropriate if delayed surgery can provide negative margins. However, for infants who are unable to undergo surgical resection, higher doses of RT remain appropriate. Radiation techniques are designed to maximize normal tissue sparing, and should include conformal approaches, often with intensity-modulated techniques.
Local Control Management with Surgery and RT by Primary Sites of Disease
Head and neck
Rhabdomyosarcomas of the orbit should not undergo exenteration, but biopsy is needed for diagnosis.[38,39] Biopsy is followed by chemotherapy and RT, with orbital exenteration reserved for the small number of patients with locally persistent or recurrent disease.[40,41] RT and chemotherapy are the standard of care, with survival in excess of 90% to 95%. For patients with orbital tumors, precautions should be taken to limit the RT dose to the lens and cornea.