Stereotactic radiosurgery in the management of petroclival meningiomas: a systematic review and meta-analysis of treatment outcomes of primary and adjuvant radiosurgery

Exploring Neuroprotection against Radiation-Induced Brain Injury: A Review of Key Compounds

Brain radiation is a crucial tool in neuro-oncology for enhancing local tumor control, but it can lead to mild-to-profound and progressive impairments in cognitive function. Radiation-induced brain injury is a significant adverse effect of radiotherapy for cranioencephalic tumors, primarily caused by indirect cellular damage through the formation of free radicals. This results in late neurotoxicity manifesting as cognitive impairment due to free radical production. The aim of this review is to highlight the role of different substances, such as drugs used in the clinical setting and antioxidants such as ascorbate, in reducing the neurotoxicity associated with radiation-induced brain injury. Currently, there is mainly preclinical and clinical evidence supporting the benefit of these interventions, representing a cost-effective and straightforward neuroprotective strategy.

[Ga68] DOTATATE PET/MRI-guided radiosurgical treatment planning and response assessment in meningiomas

BACKGROUND

Our purpose was to determine the utility of [68Ga]-DOTATATE PET/MRI in meningioma response assessment following radiosurgery.

METHODS

Patients with meningioma prospectively underwent postoperative DOTATATE PET/MRI. Co-registered PET and gadolinium-enhanced T1-weighted MRI were employed for radiosurgery planning. Follow-up DOTATATE PET/MRI was performed at 6-12 months post-radiosurgery. Maximum absolute standardized uptake value (SUV) and SUV ratio (SUVRSSS) referencing superior sagittal sinus (SSS) blood pool were obtained. Size change was determined by Response Assessment in Neuro-Oncology (RANO) criteria. Association of SUVRSSS change magnitude and progression-free survival (PFS) was evaluated using Cox regression.

RESULTS

Twenty-seven patients with 64 tumors (26% World Health Organization [WHO]-1, 41% WHO-2, 26% WHO-3, and 7% WHO-unknown) were prospectively followed post stereotactic radiosurgery (SRS) or stereotactic body radiotherapy (SBRT; mean dose: 30 Gy, modal dose 35 Gy, mean of 5 fractions). Post-irradiation SUV and SUVRSSS decreased by 37.4% and 44.4%, respectively (P < .0001). Size product decreased by 8.9%, thus failing to reach the 25% significance threshold as determined by RANO guidelines. Mean follow-up time was 26 months (range: 6-44). Overall mean PFS was 83% and 100%/100%/54% in WHO-1/-2/-3 subcohorts, respectively, at 34 months. At maximum follow-up (42-44 months), PFS was 100%/83%/54% in WHO-1/-2/-3 subcohorts, respectively. Cox regression analyses revealed a hazard ratio of 0.48 for 10-unit reduction in SUVRSSS in the SRS cohort.

CONCLUSIONS

DOTATATE PET SUV and SUVRSSS demonstrated marked, significant decrease post-radiosurgery. Lesion size decrease was statistically significant; however, it was not clinically significant by RANO criteria. DOTATATE PET/MR thus represents a promising imaging biomarker for response assessment in meningiomas treated with radiosurgery.

CLINICALTRIALS.GOV IDENTIFIER

NCT04081701.

Combined Petrosal Intertentorial Approach: A Cadaveric Study of Comparison With the Standard Combined Petrosectomy

BACKGROUND AND OBJECTIVES

The combined petrosal intertentorial approach (CPIA) has been proposed as an alternative to standard combined petrosal approach (SCPA). CPIA has been designed to maintain integrity of the temporal dura with a view to reduce temporal lobe morbidity and venous complications. This study has been designed to perform a quantitative comparison between these approaches.

METHODS

Five human specimens were used for this study. CPIA was performed on one side and SCPA on the opposite side. The area of exposure (petroclival and brainstem), surgical freedom, and angles of attack to a predefined target were measured and compared.

RESULTS

SCPA provided a significantly larger petroclival area of exposure (6.81 ± 0.60 cm2) over the CPIA (5.59 ± 0.59 cm2), P = .012. The area of brainstem exposed with SCPA was greater than with CPIA (7.17 ± 0.84 vs 5.63 ± 0.72, P = .014). The area of surgical freedom was greater in SCPA rather than in CPIA (8.59 ± 0.55 and 7.13 ± 0.96 cm2, respectively, P = .019). There was no significative difference between CPIA and SCPA in the vertical angles of attack for the Meckel cave, Dorello canal, and root entry zone of cranial nerve VII. Conversely, the horizontal angles of attack permitted by the CPIA were significantly smaller for the Meckel cave (52.36° ± 5.01° vs 64.4° ± 5.3°, P = .006) and root entry zone of cranial nerve VII (30.7° ± 4.4° vs 40.1° ± 6.2°, P = .025).

CONCLUSION

CPIA is associated with a reduction in terms of the area of surgical freedom (22%), skull base (18%), brainstem exposure (17%), and horizontal angles of attack (18%-23%) when compared with SCPA. This loss in terms of exposure is counterbalanced by the advantage of keeping the temporal lobe covered by an extra layer of meningeal tissue, thus possibly reducing the risk of temporal lobe injury and venous infarction. These results need to be validated with adequate clinical experience.

Long-term Experience of LINAC Single-Dose Radiosurgery for Skull Base Meningiomas: A Retrospective Single-Center Study of 241 Cases

BACKGROUND AND OBJECTIVES

Stereotactic radiosurgery (SRS) is increasingly applied to treat meningiomas, attributable to their increased incidence in older individuals at greater surgical risk. To evaluate the effectiveness of treatment with linear accelerator (LINAC)-based stereotactic radiosurgery in skull base meningiomas as either primary treatment or postresection adjuvant therapy.

METHODS

This study included 241 patients diagnosed with skull base meningiomas treated by single-dose SRS, with a median age of 59 years. SRS was primary treatment in 68.1% (n = 164) and adjuvant treatment in 31.9% (n = 77), using LINAC (Varian 600, 6 MeV). The median tumor volume was 3.2 cm 3 , and the median coverage dose was 14 Gy. Bivariate and multivariate analyses were performed to determine predictive factors for tumor progression, clinical deterioration, and complications. Kaplan-Meier analysis was used for survival analysis.

RESULTS

After the median follow-up of 102 months, the tumor control rate was 91.2% (n = 220). Progression-free survival rates were 97.07%, 90.1%, and 85.7% at 5, 10, and 14 years, respectively. Clinical improvement was observed in 56 patients (23.2%). In multivariate analysis, previous surgery (hazard ratio 3.8 [95%CI 1.136-12.71], P = .030) and selectivity (hazard ratio .21 [95%CI 0.066-0.677], P = .009) were associated with tumor progression and increased maximum dose (odds ratio [OR] 4.19 [95% CI 1.287-13.653], P = .017) with clinical deterioration. The permanent adverse radiation effect rate was 6.2% (n = 15) and associated with maximum brainstem dose >12.5 Gy (OR 3.36 [95% CI .866-13.03], P = .08) and cerebellopontine angle localization (OR 3.93 [95% CI 1.29-11.98], P = .016).

CONCLUSION

Treatment of skull base meningiomas with single-dose SRS using LINAC is effective over the long term. Superior tumor control is obtained in patients without previous surgery. Adverse effects are related to localization in the cerebellopontine angle, and maximum brainstem radiation dose was >12.5 Gy.

Postoperative Complications and Neurological Deficits After Petroclival Region Meningioma Resection: A Case Series

BACKGROUND

Surgical management of meningiomas involving the petroclival junction remains a challenge because of nearby critical neurovascular structures.

OBJECTIVE

To describe surgical approach selection, outcomes, and factors associated with postoperative complications and neurological deficits in a series of patients undergoing resection of petroclival region meningiomas.

METHODS

Retrospective review of patients undergoing symptomatic petroclival region meningioma resection was performed. Logistic regression was performed to identify variables associated with postoperative complications and new neurological deficits.

RESULTS

Sixty-five patients underwent 54 one-stage and 11 two-stage resections with median follow-up of 51 months. Most tumors were World Health Organization grade 1 (90.8%), and the median volume was 23.9 cm 3 . Posterior petrosectomy and anterior petrosectomy were performed in 67.1% and 6.6% of operations, respectively. The gross or near total resection rate was 15.4%, and 8 patients (12.3%) progressed on follow-up. The surgical complication rate was 26.2% with no perioperative mortalities. Postoperatively, 45.8% of patients had new, persistent neurological deficits, with cranial nerves VII palsy being most common. On multivariate analysis, higher body mass index (odds ratio [OR]: 1.1, P = .04) was associated with risk of surgical complications. Longer operative time (OR: 1.4, P = .004) and staged procedures (OR: 4.9, P = .04) were associated with risk of new neurological deficit on follow-up, likely reflecting more challenging tumors. Comparing early vs later career surgeries performed by the senior author, rates of severe complications and neurological deficits decreased 23.1% and 22.3%, respectively.

CONCLUSION

Petroclival region meningiomas remain surgically challenging, but improved outcomes are seen with surgeon experience. These data help inform patients on perioperative morbidity risk and provide a guide for surgical approach selection.

Single session versus multisession stereotactic radiosurgery for the management of intracranial meningiomas: a systematic review and meta-analysis

PURPOSE

To compare the efficacy, outcomes, and complications of single session (SS-SRS) and multisession (MS-SRS) stereotactic radiosurgery in the treatment of intracranial meningiomas.

METHODS

Relevant articles were retrieved from PubMed, Scopus, Web of Science, and Cochrane. A systematic review and meta-analysis of treatment protocols and outcomes were conducted. After the selection process, 20 articles describing 1483 cases were included.

RESULTS

A total of 1303 patients who underwent SS-SRS and 180 patients who underwent MS-SRS for the management of their intracranial meningioma were reported in the included studies. SS-SRS and MS-SRS had comparable one-year (SS-SRS: 98% vs. MS-SRS: 100%, p > 0.99) and five-year (SS-SRS: 94% vs. MS-SRS: 93%, p = 0.71) tumor control rates. The groups also had comparable tumor volume reduction/tumor regression rates (SS-SRS: 44% vs. MS-SRS: 25%, p = 0.25), tumor volume stability rates (SS-SRS: 51% vs. MS-SRS: 75%, p = 0.12), and tumor progression rates (SS-SRS: 4% vs. MS-SRS: 4%, p = 0.89). SS-SRS and MS-SRS yielded similar complication rates (10.4% vs. 11.4%, p = 0.68) and comparable functional improvement rates (MS-SRS: 44% vs. SS-SRS: 36%, p = 0.57). However, MS-SRS was used for significantly larger tumor volumes (MS-SRS: 23.8 cm³ vs. SS-SRS: 6.1 cm³, p = 0.02).

CONCLUSION

SS-SRS and MS-SRS resulted in comparable tumor control, tumor volumetric change, and functional outcomes despite significant biases in selecting patients for SS- or MS-SRS.

Adjuvant stereotactic radiosurgery with or without postoperative fractionated radiation therapy in adults with skull base chordomas: a systematic review

OBJECTIVE

The objective of this retrospective study was to compare the survival of patients with biopsy-proven skull base chordoma who had undergone stereotactic radiosurgery (SRS) with versus without prior fractionated radiation therapy (RT).

METHODS

Relevant articles from database inception to September 2021 were retrieved from the PubMed, Scopus, Web of Science, and Cochrane databases for a systematic review of treatment protocols. Studies were included if they 1) involved adult patients (age ≥ 18 years) with histologically and radiologically confirmed chordomas located within the clival skull base region and treated with SRS; 2) reported data on clinical features, SRS protocols, and outcomes; and 3) were written in the English language. Studies were excluded if they 1) were literature reviews, case reports, technical notes, abstracts, or autopsy reports; 2) did not clearly differentiate the data of patients with chordomas from the data of patients with different tumors or the data of patients with chordomas in locations other than the skull base; or 3) lacked histological confirmation or treatment and outcome data. Extracted data included the following: study author and publication year, patient age and sex, symptoms, cranial nerve involvement, invaded structures, lesion size, treatment modality, surgical details, histopathological type, RT modality, SRS parameters, complications, postradiosurgery outcomes, complications, and survival outcomes.

RESULTS

After the selection process, 15 articles describing 130 patients met the study eligibility criteria, including 94 patients who had undergone postresection SRS (NoRT group) and 36 who had undergone postresection fractionated RT and subsequent SRS (RT group). The NoRT and RT groups were comparable in age (51.3 vs 47.4 years, respectively), sex (57.1% vs 58.3% male), tumor volume (9.5 vs 11.2 cm3), SRS treatment parameters (maximum dose: 35.4 vs 42.2 Gy, marginal dose: 19.6 vs 20.6 Gy, treatment isodose line: 60.2% vs 65.2%), and SRS adverse effects (10.9% vs 17.6%). For the entire cohort, the 3-, 5-, and 10-year progression-free survival (PFS) rates were 23%, 9%, and 3%, respectively, and the overall survival (OS) rates were 94%, 82%, and 76%, respectively. In the NoRT group, SRS was adjuvant treatment after resection in 38 patients (40.4%), salvage treatment for recurrent tumor treated with resection alone in 10 (10.6%), and not specified in 46 (48.9%). In the RT group, SRS was boost treatment in 9 patients (25.0%), salvage treatment after recurrence in 22 (61.1%), and not specified in 5 (13.9%). There was no difference between the two groups in terms of median PFS (24.0 months [Q1 34.0, Q3 15.0] vs 23.8 months [34.0, 18.0], respectively; p = 0.8) or median OS (293.0 months [not reached, 137.4] vs not reached [not reached, 48.0], respectively; p = 0.36). The adverse radiation effect rates were comparable between the groups (10.9% vs 17.6%, respectively; p = 0.4).

CONCLUSIONS

The role of SRS in the management of skull base chordomas is still evolving. This systematic literature review of biopsy-proven chordoma revealed that tumor control and survival rates for SRS alone after chordoma surgery were not inferior to those encountered after SRS plus fractionated RT.

The Role of [68Ga]Ga-DOTA-SSTR PET Radiotracers in Brain Tumors: A Systematic Review of the Literature and Ongoing Clinical Trials

Simple Summary

[⁶⁸Ga]Ga-DOTA-SSTR PET imaging has recently been introduced in the management of patients with brain tumors, mostly meningiomas and pituitary adenomas or carcinomas. The current literature demonstrated the superior diagnostic accuracy of this imaging modality, especially for lesions difficult to be detected or characterized on conventional imaging protocols, such as skull base or transosseous meningiomas. [⁶⁸Ga]Ga-DOTA-SSTR PET tracers also seem to provide superior volume contouring for radiotherapy planning and may also be used to evaluate the tumor’s overexpression of somatostatin receptors for devising patient-tailored peptide receptor radionuclide therapy. In this review, we comprehensively analyzed the current literature discussing the implementation of [⁶⁸Ga]Ga-DOTA-SSTR PET imaging in brain tumors, further presenting ongoing clinical trials and suggesting potential future applications.

Abstract

Background: The development of [⁶⁸Ga]Ga-DOTA-SSTR PET tracers has garnered interest in neuro-oncology, to increase accuracy in diagnostic, radiation planning, and neurotheranostics protocols. We systematically reviewed the literature on the current uses of [⁶⁸Ga]Ga-DOTA-SSTR PET in brain tumors. Methods: PubMed, Scopus, Web of Science, and Cochrane were searched in accordance with the PRISMA guidelines to include published studies and ongoing trials utilizing [⁶⁸Ga]Ga-DOTA-SSTR PET in patients with brain tumors. Results: We included 63 published studies comprising 1030 patients with 1277 lesions, and 4 ongoing trials. [⁶⁸Ga]Ga-DOTA-SSTR PET was mostly used for diagnostic purposes (62.5%), followed by treatment planning (32.7%), and neurotheranostics (4.8%). Most lesions were meningiomas (93.6%), followed by pituitary adenomas (2.8%), and the DOTATOC tracer (53.2%) was used more frequently than DOTATATE (39.1%) and DOTANOC (5.7%), except for diagnostic purposes (DOTATATE 51.1%). [⁶⁸Ga]Ga-DOTA-SSTR PET studies were mostly required to confirm the diagnosis of meningiomas (owing to their high SSTR2 expression and tracer uptake) or evaluate their extent of bone invasion, and improve volume contouring for better radiotherapy planning. Some studies reported the uncommon occurrence of SSTR2-positive brain pathology challenging the diagnostic accuracy of [⁶⁸Ga]Ga-DOTA-SSTR PET for meningiomas. Pre-treatment assessment of tracer uptake rates has been used to confirm patient eligibility (high somatostatin receptor-2 expression) for peptide receptor radionuclide therapy (PRRT) (i.e., neurotheranostics) for recurrent meningiomas and pituitary carcinomas. Conclusion: [⁶⁸Ga]Ga-DOTA-SSTR PET studies may revolutionize the routine neuro-oncology practice, especially in meningiomas, by improving diagnostic accuracy, delineation of radiotherapy targets, and patient eligibility for radionuclide therapies.