LINAC-based Stereotactic Radiosurgery for Meningiomas

Shin, Seong Soo; Kim, Dae Yong; Ahn, Yong Chan; Lee, Jung Il; Nam, Do Hyun; Lim, Do Hoon; Huh, Seung Jae; Yeo, Inhwan J; Shin, Hyung Jin; Park, Kwan; Kim, BoKyoung; Kim, Jong Hyun

Abstract

PURPOSE: To evaluate the role of LINAC-based stereotactic radiosurgery (SRS) in the management of meningiomas, we reviewed clinical response, image response, neurological deficits for patients treated at our institution.
METHODS
AND MATERIALS: Between February 1995 and December 1999, twenty-six patients were treated with SRS. Seven patients had undergone prior resection. Nineteen patients received SRS as the initial treatment. There were 7 male and 19 female patients. The median age was 51 years (range, 14~67 years). At least one clinical symptom presented at the time of SRS in 17 patients and cranial neuropathy was seen in 7 patients. The median tumor volume was 4.7 cm3 (range, 0.7~16.5 cm3). The mean marginal dose was 15 Gy (range, 10~20 Gy), delivered to the 80% isodose surface (range, 46~90%). The median clinical and imaging follow-up periods were 27 months (range, 1-71 months) and 25 months (range, 1~52 months), respectively.
RESULTS
Of 14 patients who had clinical follow-up of one year or longer, thirteen patients (93%) were improved clinically at follow-up examination. Clinical symptom worsened in one patient at 4 months after SRS as a result of intratumoral edema, who underwent surgical resection at 7 months. Of 14 patients who had radiologic follow-up of one year or longer, tumor volume decreased in 7 patients (50%) at a median of 11 months (range, 6~25 months), remained stable in 6 patients (43%), and increased in one patient (7%), who underwent surgical resection at 44 months. New radiation-induced neurological deficits developed in six patients (23%). Five patients (19%) had transient neurological deficits, completely resolved by conservative treatment including steroid therapy. Radiation-induced brain necrosis developed in one patient (3.8%) at 9 months after SRS who followed by surgical resection of tumor and necrotic tissue.
CONCLUSIONS
LINAC-based SRS proves to be an effective and safe management strategy for small to moderate sized meningiomas, inoperable, residual, and recurrent, but long-term follow-up will be necessary to fully evaluate its efficacy. To reduce the radiation-induced neurological deficit for large size meningioma and/or in the proximity of critical and neural structure, more delicate treatment planning and optimal decision of radiation dose will be necessary.