Multi-session radiosurgery of benign intracranial tumors

The Role of Stereotactic Radiosurgery in the Management of Foramen Magnum Meningiomas-A Multicenter Analysis and Review of the Literature

Simple Summary

Meningiomas represent the most common central nervous system (CNS) tumor. Despite their often benign nature, a tumor location in direct proximity to vital brain structures may lead to significant morbidity. This is the case for foramen magnum meningiomas (FMMs) as they grow at the skull base, next to the brain stem and foramen magnum. Surgical resection represents the mainstay of FMM treatments. In patients unsuitable for surgery, with tumor recurrences or tumor remnants after surgery, non-invasive treatment modalities may play a crucial role in patient management. Reports and studies on stereotactic radiosurgery (SRS) for the treatment of FMMs are scarce. This multicenter analysis reported the outcome data of 62 patients with FMMs. SRS achieved a high local tumor control and demonstrated a favorable safety profile. These results are in agreement with previous findings. SRS should be considered for selected FMM patients.

Abstract

Background: Foramen magnum meningiomas (FMMs) represent a considerable neurosurgical challenge given their location and potential morbidity. Stereotactic radiosurgery (SRS) is an established non-invasive treatment modality for various benign and malignant brain tumors. However, reports on single-session or multisession SRS for the management and treatment of FMMs are exceedingly rare. We report the largest FMM SRS series to date and describe our multicenter treatment experience utilizing robotic radiosurgery. Methods: Patients who underwent SRS between 2005 and 2020 as a treatment for a FMM at six different centers were eligible for analysis. Results: Sixty-two patients met the inclusion criteria. The median follow-up was 28.9 months. The median prescription dose and isodose line were 14 Gy and 70%, respectively. Single-session SRS accounted for 81% of treatments. The remaining patients received three to five fractions, with doses ranging from 19.5 to 25 Gy. Ten (16%) patients were treated for a tumor recurrence after surgery, and thirteen (21%) underwent adjuvant treatment. The remaining 39 FMMs (63%) received SRS as their primary treatment. For patients with an upfront surgical resection, histopathological examination revealed 22 World Health Organization grade I tumors and one grade II FMM. The median tumor volume was 2.6 cubic centimeters. No local failures were observed throughout the available follow-up, including patients with a follow-up ≥ five years (16 patients), leading to an overall local control of 100%. Tumor volume significantly decreased after treatment, with a median volume reduction of 21% at the last available follow-up (p < 0.01). The one-, three-, and five-year progression-free survival were 100%, 96.6%, and 93.0%, respectively. Most patients showed stable (47%) or improved (21%) neurological deficits at the last follow-up. No high-grade adverse events were observed. Conclusions: SRS is an effective and safe treatment modality for FMMs. Despite the paucity of available data and previous reports, SRS should be considered for selected patients, especially those with subtotal tumor resections, recurrences, and patients not suitable for surgery.

Stereotactic Radiosurgery and Hypofractionated Stereotactic Radiotherapy for Nonfunctioning Pituitary Adenoma

Objectives  Hypofractionated stereotactic radiotherapy (HSRT) in two to five fractions may offer patients with large nonfunctioning pituitary adenomas (NFPAs) with chiasm involvement a safe and effective treatment over a single week. However, little has been reported regarding this novel approach. Design  We compared the feasibility, outcomes, and toxicity of single-fraction stereotactic radiosurgery and HSRT. Setting  This study was conducted at a tertiary academic referral center. Participants  After approval by the institutional review board, we performed a retrospective cohort study of patients treated at our institution with stereotactic radiosurgery (SRS) and HSRT for NFPA. Selection for SRS or HSRT was based on clinicopathologic factors including tumor size and cavernous sinus invasion at the discretion of the treating physician. Main Outcome Measures  Local control, endocrinopathy, and radiation-associated toxicity were evaluated by binary logistic regression and Cox's proportional hazards regression. Results  A total of 45 patients with mean follow-up of 5 years were enrolled including 26 patients treated by HSRT with mean follow-up of 3 years and 19 patients treated by SRS with median follow-up of 6 years. Clinicopathologic characteristics were balanced between cohorts. Local failure at last follow-up was 5% in the SRS cohort and 8% in the HSRT cohort, and rates of post-SRS endocrinopathy were similar between each cohort. Late complications including radionecrosis, visual deficit, and secondary malignancy were minimal in either cohort. Conclusions  HSRT is an appropriate treatment strategy for patients with NFPAs, particularly for optic pathway preservation in the setting of large tumors with chiasm involvement. Further studies are needed to optimize fractionated approaches and patient selection.

Partial skull base tumour resection in combination with radiosurgery: an escape procedure or a reasonable solution of treatment?

Despite advancement in microsurgical techniques for skull base tumour surgery, approaches of this kind still represent a significant challenge for neurosurgeons due to the size of the tumour and its interference and proximity to important neural and vascular structures. After incomplete resection, gamma knife radiosurgery is becoming an alternative or adjunctive treatment option. In this article, some examples of our experience in combined treatment of the skull base tumours with surgical procedure and gamma knife therapy for the remaining tumour tissue are presented.