gms | German Medical Science

Objective: The therapy of choice for meningiomas is still microsurgery. In cases with eloquent localizations many surgeons prefer a subtotal resection to avoid morbidity. Numerous short- and intermediate-term studies had proven that SRS promises high tumor control rate and low morbidity as primary treatment and for recurrent or residual meningiomas. We present our radiological and clinical outcome of LINAC RS for benign cranial meningiomas with a median follow-up of 10 years and a minimum follow-up of 5 years.

Methods: 139 patients with 157 lesions and a minimum follow-up of 5 years were included into this observation study. All showed radiological or histological findings of benign meningiomas. 79 meningiomas were treated by LINAC based stereotactic radiosurgery as primary treatment and 78 for residual or recurrent meningiomas. 107 meningiomas were located at the skull base with involvement of the cavernous sinus in 75 cases, 35 at the falx and 15 at the convexity. According to the irradiation parameters a median surface dose of 12 Gy (range: 7–20 Gy) was applied and a median maximum dose of 29 Gy (range 11.3–58.6 Gy) was achieved. The median target volume was 4.75 ml (range: 0.2–32.8 ml).

Results: The mean radiological follow-up was 10.5 years (median 10.2 years, range 5.1–23.5 years). A favourable tumor shrinkage was observed in 66/157 (42.0%) meningiomas. 86/157 (54.7%) showed no changes in size and in only 5/157 (3.2%) a local tumor progression was seen. The overall tumor control rate (TCR) was 97% and the progression free survival (PFS) was 96%, 90% and 89% after 5, 10 and 15 years. The corresponding TCR was 94% and PFS was 92%, 86% and 86% for SRS treated residual or recurrent meningiomas. For primary treated meningiomas the TCR was 100% and PFS was 100%, 95% and 95% after 5, 10 and 15 years, respectively. Regarding the clinical status after a mean clinical follow-up of 12 years (median 11.2 months, range 5.6–25.6 years) clinical improvement was observed in 56 / 139 patients (40.3%). The clinical status remained unchanged in 74 / 139 (53.2%) and deteriorated in 9 / 139 patients (6.5%).

Conclusions: These results underline the safety and efficacy of LINAC-SRS for benign meningiomas. Yielding a high local tumor control rate with low morbidity SRS should be considered as one arm of a combined treatment for incompletely resected or recurrent meningiomas. For small and surgically high risk meningiomas SRS should be preferred to microsurgery.