(P 203) MULTIDISCIPLINARY APPROACH OF ADVANCED-STAGE ALVEOLAR RHABDOMYOSARCOMA OF THE MAXILLARY SINUS IN ADULTS: A CASE REPORT

Objective: Alveolar rhabdomyosarcoma (ARMS) is a rare soft-tissue malignancy that is common in children, but it is extremely rare in adults. Since the clinical course and the treatment strategy for advanced disease are not well established yet , we emphasize the role of multidisciplinary (MD) approach in this setting of patients.

Methods: We present a case of a 50-year-old woman with ARMS of right maxillary sinus in stage IV: T4 (6cm) N1 (ipsilateral laterocervical node) M1 (multiple bone metastasis, the most critical one of C7 vertebra with invasion of spinal canal) )[Figure 1 ]. Initially, the patient presented with moderate pain of the right shoulder and paresthesia of the extremities that improved with administration of the analgesics. Considering rarity of the tumor, histopathological review was performed confirming the diagnosis. After the MD evaluation, due to the extent and chemosensitivity of the disease, and the paucisymptomaticity of the patient, prior chemotherapy (CT) was proposed. Sequential radiotherapy (RT) was recommended after the initial response to CT. A total of 9 cycles of CT were administered: first cycle with Vincristine- Adriamycin- Ciclofosfamide, followed by 4 cycles of Vincristin-Adriamycin-Ifosfamide and 4 cycles of Ifosfamide- Etoposide. Additionally, Denosumab was given for the bone lesions. The PET scan performed after 9 cycles of CT showed complete metabolic response of the disease and the patient was referred for exclusive radiotherapy of the primary tumor and locoregional nodes. Considering the systemic aggressiveness of the ARMS, maintenance dose of Ciclofosfamide-Vinorelbin was prescribed concomitantly. The Patient received Image-guided photon-based RT with Volumetric Modulated Arc Therapy, for a total dose of 54Gy in 30 fractions (1,8Gy/fraction, 5 days/week) on both primary tumor and ipsilateral neck. The target volumes were defined on pre-chemotherapy imaging [Figure 2].

Results: Both treatments were well tolerated and no Grade ≥2 toxicity was documented. Eight months after conclusion of RT and 17 months from the diagnosis, the patient is alive and in complete response on all sites of the disease (Figure 3). Currently the patient is undergoing maintenance CT and regular follow ups [Figure 3].

Conclusion: Adults with ARMS have a very poor prognosis due to the advanced stage of the disease at diagnosis and the high metastatic potential. A multidisciplinary approach to these patients with surgery when feasible, CT and RT is the best current therapy, though long-term survivors remain poor.