Sarcomas of the skull base. Treatment, outcome and prognostic factors

Aims. Sarcomas of the skull base is a rare pathology. Head and neck involved only in 15-20% of all sarcomas cases. Local relapse is the main reason of cure fails in patients (pts) with sarcomas of the skull base. In this link forced local control is the corner stone of successful treatment. Materials and methods. 81 pts with different types of sarcomas of the skull base treated at our clinic during the last 30 years. Pts age varied between 13-80 years. The majority of soft tissue sarcomas (n=44) consisted of tumors located in infratemporal fossa - 50% (n=22) and paranasal sinuses - 34,1% (n=15). Of bone sarcomas it were maxilla - 38,5% (n=15), ethmoid bone - 20,5% (n=8) and mandibula with second involvement of infratemporal fossa - 12,8% (n=5). The main morphological types of soft tissue sarcomas were - rabdomyosarcoma (29,5%, n=13), malignant shwannoma (22,7%, n=10) and malignant fibrous hystiocytoma (18,2%, n=8). In a group of bone sarcomas they were - osteosarcoma (29,7%, n=ll) and chondrosarcoma (24 ,3%, n=9). Previously untreated cases diagnosed in 68 pts and 13 pts had recurrence sarcomas. The majority of cases consisted of advanced tumors in the limits of the scull base. Cure tactic in a study group depends on several factors: tumor morphology, tumor volume and chemoradio sensitivity. The main treatment choice was surgery (70%, n=56) alone or in combination with chemoradiotherapy (32,1%). 22(27,5%) pts had conservative treatment course. Different types of surgical approaches were used for tumor removal: transfacial resections (n=32), combined craniofacial resections (n=6), resections of the lateral skull base (n=16), posterior skull base approaches (n=2). Results. The most favorable 5-year overall survival rate was pointed out for a soft tissue sarcomas - 33,2%. 5-year overall survival rate for embryonal type of rabdomyosarcoma was 24,3% (median 13,5 months), chondrosarcoma - 23,5% (median 23 months). The worse results were pictured for malignant shwannoma, osteosarcoma and Ewing/PNET sarcomas where none of the pts overlive 5 year period. Pts with chemoradiotherapy had little improvement in a group of soft tissue sarcomas. Chemoradiotherapy had not any benefits in treatment of bone sarcomas, so 5-year overall survival rate was most favorable in a group of surgical cure - 23% (median 16,5 months) in comparison with conservative (6,3%, median 16 months) and complex treatment (0%, median 12 months) (p=0,l). Total tumor resection was the main prognostic factor associated with better outcome. Local recurrence rate was significantly higher in a group of unradical operations - 73,3% vs 51,2% (radical surgery) (p=0,02). Among factors associated with negative prognosis were - recurrence tumors, primary regional node involvement, tumor spread into the cavernous sinus, primary tumor involvement of the posterior skull base or combined destruction of anterior and lateral skull base. Conclusions. Embryonal rabdomyosarcoma and chondrosarcoma associated with the most favorable follow-up. Chemoradiotherapy doesn’t improve outcome for bone sarcomas and malignant shwannoma of the skull base. On the other hand chemoradiotherapy can potentially decrease local recurrence rate in a group of soft tissue sarcomas. Surgery appears to be a method of choice in a treatment of the majority of skull base sarcomas, especially of bone sarcomas, residual and chemoradioresistant tumors.

sarcomas, skull base, surgery, chemotherapy, radiotherapy