What is the role of radiation in the treatment of rhabdomyosarcoma?

Updated: Feb 01, 2019
  • Author: Amelia F Drake, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

Answer

The location and extent of disease after surgical management largely determine the doses for radiation treatment. In general, a margin of 2 cm around the tumor and involved nodes is the guideline for the treatment volume.

Chemotherapy is typically administered for 2-3 months before the start of radiation therapy. Radiation treatment is then administered for approximately 5-6 weeks. The only exception to this rule involves patients with parameningeal disease and evidence of meningeal spread. In this circumstance, radiation is started at the time of diagnosis. During radiation treatment, doses of chemotherapy are altered to avoid the use of radiosensitizing agents (eg, dactinomycin, doxorubicin). Patients with encranial meningeal extension of parameningeal rhabdomyosarcoma should receive whole-brain irradiation in addition to radiotherapy of the primary tumor.

In general, irradiation is good for patients with evidence of gross or microscopic residual disease after resection. Patients in group I (complete resection) typically do well without irradiation. However, radiation therapy may be of some benefit in patients with alveolar histology, who may otherwise have a less favorable prognosis.

Patients in clinical group II typically receive total radiation doses of 4100 cGy. Individuals in group III receive approximately 5000 cGy. Although this dose is associated with a relapse rate of more than 30%, the long-term toxic effects of increasing the total dose make more aggressive treatments unfeasible. Current investigators are examining hyperfractionization and brachytherapy as alternatives to current treatment methods. In addition, newer studies indicate that improved risk stratification enables decreased therapy intensity for selected patients without compromising survival. [20]

A study by Clement et al indicated that long-term survivors of pediatric head and neck rhabdomyosarcoma are at a significantly increased risk of developing pituitary dysfunction, owing to treatment with radiation therapy. The study, of 80 survivors of head and neck rhabdomyosarcoma, reported pituitary dysfunction in 24 of them (30%) after a median 11-year follow-up period, with risk factors for such dysfunction including external beam radiation therapy (EBRT), a parameningeal tumor site, and embryonal rhabdomyosarcoma subtype. Children treated with the AMORE (ablative surgery, moulage technique brachytherapy, surgical reconstruction) protocol were less likely than those treated with EBRT to develop pituitary dysfunction. [21]

A study by Mattos et al indicated that chemoradiotherapy in children with head and neck rhabdomyosarcoma can significantly impact dental and craniofacial features. The investigators found 603 dental alterations—most frequently, root shortening—among the study’s 27 patients, with 377 such changes (62.5%) appearing in patients aged 5 years or younger. The study also reported the presence of facial asymmetry (74% of patients), reduced facial depth (70.4% of patients), short-sized mandibles (48.4% of patients), and reduced facial height (77.8% of patients). [22]


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