Radiation Therapy Information

As much as we are 'freaked out' that Adam will have to get radiation therapy, according to the literature the outcomes are better. Adam fits into 'Group II' of this article.

Radiation Therapy Management Options
Radiation therapy is an effective method for achieving local control of tumor for patients with microscopic or gross residual disease following biopsy, initial surgical resection, or chemotherapy. Patients with completely resected tumors (Group I) of embryonal histology do well without radiation therapy,[44,45] but radiation therapy benefits patients with Group I tumors with alveolar or undifferentiated histology.[69] A review of European trials conducted by the Cooperative Soft Tissue Sarcoma Study Group between 1981 and 1998 in which radiation therapy was omitted for some Group II patients demonstrated a benefit to using radiation therapy as a component of local tumor control for all Group II patient subsets (defined by tumor histology, tumor size, and tumor site).[70] Local failure is the predominant type of relapse for patients with Group III disease. Patients with tumor-involved regional lymph nodes at diagnosis have a higher risk of local and distant failure compared with patients whose lymph nodes are negative.[71] As with the surgical management of patients with rhabdomyosarcoma, recommendations for radiation therapy are dependent on the site of primary tumor and on the amount of residual disease, if any, following surgical resection. For patients with head and neck rhabdomyosarcoma, one study reported excellent local control in 28 patients treated with intensity-modulated radiotherapy (IMRT) and chemotherapy over a 4-year period. Further study is needed, but the use of IMRT and chemotherapy in patients with head and neck rhabdomyosarcoma may result in less severe late effects.[72]

For optimal care of pediatric patients undergoing radiation treatments, it is imperative to have a radiation oncologist, radiation technicians, and nurses who are experienced in treating children. An anesthesiologist may be necessary to help sedate and immobilize young patients. The facility should be equipped with a linear accelerator and have the capabilities to administer electron beam therapy. Computerized treatment planning with a three-dimensional planning system should be available. Techniques to deliver radiation specifically to the tumor while sparing normal tissue (e.g., conformal radiation, intensity-modulated radiation therapy, or proton-beam therapy) should be considered.[73,74]

Standard treatment options
The radiation therapy dose depends predominantly on the amount of residual disease, if any, following the primary surgical resection. In general, patients with microscopic residual disease (Group II) receive radiation therapy to approximately 41 Gy,[69,75] though doses from 30 to 40 Gy may be adequate in patients receiving effective multiagent chemotherapy.[76] IRS-II patients with gross residual disease (Group III) who received 40 Gy to more than 50 Gy had locoregional relapse rates greater than 30%; higher doses of radiation (>60 Gy) have been associated with unacceptable long-term toxic effects.[77,78] Group III patients on the IRS-IV standard treatment arm received 50.4 Gy.[79]

The treated volume should be determined by the extent of tumor at diagnosis prior to surgical resection and prior to chemotherapy. A margin of 2 cm is generally used, including clinically involved regional lymph nodes.[69] While the volume irradiated may be modified based on guidelines for normal tissue tolerance, gross residual disease at the time of radiation should receive full-dose treatment.

The timing of radiation therapy generally allows for chemotherapy to be given for 1 to 3 months prior to the initiation of radiation therapy. In current COG protocols, patients with parameningeal disease who have evidence of meningeal extension start radiation therapy at the beginning of treatment.[45,80,81] A prospective trial of 26 patients with Group III parameningeal rhabdomyosarcoma achieved good local control and survival with radiation therapy administered at the conventional time.[82] Radiation therapy is usually given for 5 to 6 weeks (e.g., 1.8 Gy per day for 28 treatment days), during which time chemotherapy is usually modified to avoid the radiosensitizing agents dactinomycin and doxorubicin.