[Optimal postoperative radiotherapy treatment of orbital rhabdomyosarcoma]

Rhabdomyosarcoma (RMS) is the most common sarcoma of the soft tissue, mostly affecting the region of head and neck (orbit, paranasal sinus). Histological types include embryonal (66-70%) with better prognosis, and alveolar type (20%) with poorer prognosis. There are also diffuse anaplastic and undifferentiated sarcomas (10%). Due to multimodal therapy approach (surgery, chemotherapy and radiotherapy), RMS survival rate is considerably improving. Nevertheless, early diagnosis of RMS is of crucial importance for the outcome of treatment. Standard conformal radiation therapy is very complex due to closeness of many critical structures of head and neck, thus limiting optimal tumor dose coverage.

Patient aged 59 years, surgically treated for RMS of nasal cavity several times before radiation therapy treatment. Due to relapse, patient was re-operated, when subtotal re-resection of the maxilla with exenteration of the right orbit was done. The patient received IV cycles of polychemotherapy postoperatively. Standard procedure and planning for conformal radiation therapy did not lead to acceptable irradiation plan, and hence modification in the patient's preparation was done, resulting in optimal therapeutic plan according to internationally recognized recommendations.

The reported case shows a rare pediatric tumor, which often occurs in children but extremely rare in adults. The problem of inadequate isodose distribution obtained by standard conformal plan was solved by placing bolus material into the orbital cavity.The outcome of the treatment plan showed much better isodose distribution and tumor bed coverage.