Gamma Knife surgery for benign meningioma

• Published in: Journal of neurosurgery Vol. 107; no. 2; p. 325
• Main Authors: Kollová, Aurelia, Liscák, Roman, Novotný, Jr, Josef, Vladyka, Vilibald, Simonová, Gabriela, Janousková, Ladislava
• Format: Journal Article
• Language: English
• Published: United States 01.08.2007
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Female; Follow-Up Studies; Humans; Male; Meningeal Neoplasms - pathology; Meningeal Neoplasms - surgery; Meningioma - pathology; Meningioma - surgery; Middle Aged; Radiosurgery - adverse effects; Retrospective Studies; Time Factors; Treatment Outcome; Tumor Burden
• ISSN: 0022-3085
• DOI: 10.3171/jns-07/08/0325

Meningioma is the most frequent benign tumor treated with Gamma Knife surgery (GKS); however, the assessment of its efficacy and safety in slow-growing tumors is an ongoing process, requiring analysis of long-term results. Three hundred sixty-eight patients harboring 400 meningiomas treated between 1992 and 1999 at Na Homolce Hospital were evaluated. The median patient age was 57 years (range 18-84 years). The median tumor volume was 4.4 cm3 (range 0.11-44.9 cm3). The median tumor margin dose to the 50% isodose line was 12.55 Gy (range 6.5-24 Gy). Descriptive analysis was performed in 331 patients (90%); 325 patients had a follow-up longer than 24 months (median 60 months), and six patients were included because of posttreatment complications. The volume of treated tumors decreased in 248 cases (69.7%), remained the same in 99 (27.8%), and increased in nine (2.5%). The actuarial tumor control rate was 97.9% at 5 years post-GKS. Perilesional edema after radiosurgery was confirmed on neuroimaging in 51 patients (15.4%). The temporary and permanent morbidity rates after radiosurgery were 10.2 and 5.7%, respectively. A significantly higher incidence of tumor volume increase was observed in men compared with women and in tumors treated with a margin dose lower than 12 Gy. Significant risk factors for edema included an age greater than 60 years, no previous surgery, perilesional edema before radiosurgery, a tumor volume greater than 10 cm3, a tumor location in the anterior fossa, and a margin dose greater than 16 Gy. Stereotactic radiosurgery is a safe method of treatment for meningiomas. A minimum margin dose of 12 to 16 Gy seems to represent the therapeutic window for benign meningiomas with a high tumor control rate in a mid-term follow-up period.