Clinical outcomes of benign brain tumors treated with single fraction LINAC-based stereotactic radiosurgery: Experience of a single institute

Chia-Hui Chew; Jin-Cherng Chen; Shih-Kai Hung; Tsung-Hsien Wu; Moon-Sing Lee; Wen-Yen Chiou; Liang-Cheng Chen; Hon-Yi Lin

doi:10.4103/tcmj.tcmj_260_21

Clinical outcomes of benign brain tumors treated with single fraction LINAC-based stereotactic radiosurgery: Experience of a single institute

Tzu Chi Med J. 2022 Jun 27;34(4):462-472. doi: 10.4103/tcmj.tcmj_260_21. eCollection 2022 Oct-Dec.

Authors

Chia-Hui Chew¹, Jin-Cherng Chen², Shih-Kai Hung^{1

3}, Tsung-Hsien Wu², Moon-Sing Lee^{1

3}, Wen-Yen Chiou^{1

3}, Liang-Cheng Chen^{1

3}, Hon-Yi Lin^{1

3

4}

Affiliations

¹ Department of Radiation Oncology, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
² Department of Neurosurgery, Dalin Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Chiayi, Taiwan.
³ School of Medicine, Tzu Chi University, Hualien, Taiwan.
⁴ Institute of Molecular Biology, National Chung Cheng University, Chiayi, Taiwan.

Abstract

Objectives: Accelerator-based stereotactic radiosurgery (SRS) is a noninvasive and effective treatment modality widely used for benign brain tumors. This study aims to report 20-year treatment outcomes in our institute.

Materials and methods: From May 2001 to December 2020, 127 patients treated with LINAC-based single-fraction SRS for their benign brain lesions were included. A neurosurgeon and two radiation oncologists retrospectively reviewed all data. Computed tomography (CT) simulation was performed after head-frame fixation under local anesthesia. All planning CT images were co-registered and fused with gadolinium-enhanced magnetic resonance imaging taken within 3 months for lesions targeting and critical organs delineation. The marginal dose was prescribed at 60%-90% isodose lines, respectively, to cover ≥95% planning target volume. Outcome evaluations included clinical tumor control rate (TCR), defined as the need for salvage therapy, and radiological response, defined as no enlargement of >2 cm in the maximal diameter. Overall survival (OS) and adverse reaction (defined according to CTCAE 5.0) were also analyzed.

Results: The present study included 76 female and 51 male patients for analysis. The median age was 59 years (range, 20-88 years). Their diagnoses were vestibular schwannoma (VS, n = 54), nonvestibular cranial nerve schwannoma (n = 6), meningioma (n = 50), and pituitary adenoma (n = 17). Totally 136 lesions were treated in a single fraction, predominantly skull base tumors, accounting for 69.1%. Median and mean follow-up duration was 49 and 61 months (range, 1-214 months), Overall TCR was 92.9%. The 5-year disease-specific TCR for VS, nonvestibular schwannoma, meningioma, and pituitary adenoma were 97.4%, 91.7%, 93.8%, and 83.3%. Salvage therapy was indicated for eight patients at 4-110 months after SRS. Among symptomatic patients, post-SRS symptom(s) was improved, stable, and worse in 68.2%, 24.3%, and 3.6%, respectively. Radiological response rate for 111 evaluable patients was 94.6% (shrinkage, 28.8%; stable, 65.8%). OS was 96.1% without treatment-related mortality. One patient with post-SRS cranial nerve injury (0.8%, involving the trigeminal nerve, grade 2 toxicities). No grade 3-4 acute or late toxicity was found.

Conclusion: Our results suggested that LINAC-based SRS effectively controls tumor growth and tumor-related neurological symptoms for patients with benign brain tumors. SRS is less aggressive, associated with low neurological morbidity and no mortality. Continuous follow-up is indicated to conclude longer outcomes.

Keywords: Benign brain tumor; LINAC; Stereotactic radiosurgery; Tumor control rate.