Object: Stereotactic radiosurgery has been reported to be an effective alternative to surgical removal of small to medium benign meningiomas as well as an adjuvant treatment modality to reduce the risk of tumor progression after subtotal resection. Its efficacy has been proved by excellent short-term radiosurgically demonstrated control rates, which have been reported to approach or exceed 90% in many contemporary studies involving the use of either linear accelerator-based systems or the Gamma Knife. Little is known, however, regarding the growth patterns of meningiomas that fail to stabilize after radiosurgery.
Methods: The authors report 13 cases of benign skull base meningiomas (World Health Organization Grade I) that demonstrated progression after radiosurgical treatment as a primary or an adjuvant therapy. Several tumors demonstrated rapid growth immediately after radiosurgical treatment, whereas other lesions progressed in a very delayed manner in some patients (up to 14 years after treatment). Regardless of the interval after which it occurs, tumor growth can be quite aggressive once it has begun.
Conclusions: Skull base meningioma growth can be aggressive after failed radiosurgery in some patients, and treatment failure can occur at long intervals following treatment. Special attention must be devoted to such significant occurrences given the increasing number of patients undergoing stereotactic radiosurgery for benign tumors, and careful extended (> 10 years) follow up must be undertaken in all patients after radiosurgery.