The role of stereotactic radiosurgery in the treatment of malignant skull base tumors

Purpose: To determine the efficacy and toxicity of stereotactic radiosurgery in the treatment of malignant skull base tumors. Methods and Materials: Thirty-two patients with 35 newly diagnosed or recurrent malignant skull base tumors ≤33.5 cm³ were treated using the Leksell Gamma unit. Tumor histologies included: adenoid cystic carcinoma [12], basal cell carcinoma [1], chondrosarcoma [1], chordoma [8], nasopharyngeal carcinoma [3], osteogenic sarcoma [2], and squamous cell carcinoma [8]. Results: After a median follow-up of 2.3 years, 83% ± 15% (±95% confidence interval) of patients experienced a symptomatic response to treatment. Local control at the skull base was 95 ± 9% at 2 years and 78 ± 23% at 3 years. Local- regional control above the clavicles was 75 ± 15% at 1 year and 51 ± 20% at 2 years. Overall and cause specific survival were identical, 82 ± 13% at 1 year, 76 ± 14% at 2 years, and 72 ± 16% at 3 years. One patient developed a radiation-induced optic neuropathy 12 months after radiosurgery. Conclusion: Stereotactic radiosurgery using the Leksell Gamma Unit can provide durable tumor control and symptomatic relief with acceptable toxicity in the majority of patients with malignant tumors 4 cm or less in size involving the skull base. Further evaluation of more patients with longer follow-up is warranted.