Linear Accelerator Radiosurgery for Recurrent Malignant Tumors of the Skull Base

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Abstract
The efficacy of linear accelerator-based radiosurgery for patients who have preirradiated recurrent nasopharyngeal carcinomas and unresectable recurrent sarcomas invading the base of skull was assessed. Thirteen patients were treated: 8 patients had carcinomas arising from the nasopharynx (lymphoepithelioma, 4; squamous cell carcinoma, 2; adenoid-cystic, 2); 5 patients had sarcomas (rhabdomyosarcoma, 1; chordoma, 1; chondrosarcoma, 1; hemangiopericytoma, 2). All patients had had repeated tumor resections or irradiation, hindering any further conventional fractionated radiotherapy or surgery. Convergent-beam irradiation was performed with a modified linear accelerator (8-MeV photons). Because of irregular tumor configuration, multiple (up to seven) isocenters had to be used in 10 of 13 patients to match the target volume with the reference isodose (60%-80%). Each isocenter was irradiated with 6 to 10 arcs. The median planning target volume was 33 mL (4-128 mL) and the median dose was 15 Gy (9-24 Gy). Median survival time was 9 months in 8 patients who had recurrent nasopharyngeal carcinomas. Three patients who had complete or partial tumor remission survived 1.5 to 3.5 years. All of the sarcoma patients responded to radiosurgery. After a follow-up of 28 to 67 months, 4 of 5 patients are alive. This investigation demonstrates that radiosurgery is an effective tool in palliative treatment for patients who have recurrent, extensively pretreated nasopharyngeal cancer. Patients who have recurrent sarcomas of the base of skull may be treated for long-term palliation or even for cure.