Stereotactic Radiosurgery for Pediatric and Adult Intracranial and Spinal Ependymomas

The Role of CyberKnife Stereotactic Radiosurgery in Recurrent Cranial Medulloblastomas across Pediatric and Adult Populations

Background/Objectives: Medulloblastoma is the most common malignant brain tumor in children. In recent decades, the therapeutic landscape has undergone significant changes, with stereotactic radiosurgery (SRS) emerging as a promising treatment for recurrent cases. Our study provides a comprehensive analysis of the long-term efficacy and safety of SRS in recurrent medulloblastomas across both pediatric and adult patients at a single institution. Methods: We retrospectively reviewed the clinical and radiological records of patients who underwent CyberKnife SRS for recurrent cranial medulloblastomas at our institution between 1998 and 2023. Follow-up data were available for 15 medulloblastomas in 10 patients. The cohort comprised eight pediatric patients (ages 3-18) and two adult patients (ages 19-75). The median age at the time of SRS was 13 years, the median tumor volume accounted for 1.9 cc, the median biologically equivalent dose (BED) was 126 Gy, and the single-fraction equivalent dose (SFED) was 18 Gy. The SRS was administered at 75% of the median isodose line. Results: Following a median follow-up of 39 months (range: 6-78), 53.3% of the medulloblastomas progressed, 13.3% regressed, and 33.3% remained stable. The 3-year local tumor control (LTC) rate for all medulloblastomas was 65%, with lower rates observed in the adult cohort (50%) and higher rates in pediatric patients (67%). The 3-year overall survival (OS) rate was 70%, with significantly higher rates in pediatric patients (75%) compared to adult patients (50%). The 3-year progression-free survival (PFS) rate was 58.3%, with higher rates in pediatric patients (60%) compared to adult patients (50%). Two pediatric patients developed radiation-induced edema, while two adult patients experienced radiation necrosis at the latest follow-up, with both adult patients passing away. Conclusions: Our study provides a complex perspective on the efficacy and safety of CyberKnife SRS in treating recurrent cranial medulloblastomas across pediatric and adult populations. The rarity of adverse radiation events (AREs) underscores the safety profile of SRS, reinforcing its role in enhancing treatment outcomes. The intricacies of symptomatic outcomes, intertwined with factors such as age, tumor location, and prior surgeries, emphasize the need for personalized treatment approaches. Our findings underscore the imperative for ongoing research and the development of more refined treatment strategies for recurrent medulloblastomas. Given the observed disparities in treatment outcomes, a more meticulous tailoring of treatment approaches becomes crucial.

Stereotactic Radiosurgery for Ependymoma in Pediatric and Adult Patients: A Single-Institution Experience

BACKGROUND AND OBJECTIVES

Ependymoma is commonly classified as World Health Organization grade 2 with the anaplastic variant categorized as grade 3. Incomplete resection or anaplastic features can result in unfavorable outcomes. Stereotactic radiosurgery (SRS) provides a minimally invasive approach for recurrent ependymomas. Our study investigates the efficacy and safety of SRS for grade 2 and 3 ependymomas in pediatric and adult populations.

METHODS

We conducted a retrospective analysis on 34 patients with 75 ependymomas after CyberKnife SRS between 1998 and 2023. Fourteen were pediatric (3-18 years), and 20 were adult (19-75 years) patients. The median age was 21 years, and the median tumor volume was 0.64 cc. The median single-fraction equivalent dose was 16.6 Gy, with SRS administered at 77% of the median isodose line.

RESULTS

After a median follow-up of 42.7 months (range: 3.8-438.3), 22.7% of ependymomas progressed. The 5-year local tumor control rate was 78.1%, varying between 59.6% and 90.2% for children and adults, with grade 2 at 85.9% compared with 58.5% for grade 3 tumors. The 5-year overall survival rate was 73.6%, notably higher in adults (94.7%) than in children (41%), and 100% for grade 2 but decreased to 35.9% for grade 3 patients. The 5-year progression-free survival rate was 68.5%, with 78.3% and 49.2% for adults and children, respectively, and a favorable 88.8% for grade 2, contrasting with 32.6% for grade 3 patients. Symptom improvement was observed in 85.3% of patients. Adverse radiation effects occurred in 21.4% of pediatric patients.

CONCLUSION

Our study supports SRS as a viable modality for pediatric and adult patients with grade 2 and 3 ependymomas. Despite lower local tumor control in pediatric and grade 3 cases, integrating SRS holds promise for improved outcomes. Emphasizing careful patient selection, personalized treatment planning, and long-term follow-up is crucial for optimal neurosurgical outcomes.

Radiotherapy for Brain Metastases from Thyroid Cancer: An Institutional and National Retrospective Cohort Study

Background: Stereotactic radiosurgery (SRS) is the standard of care for patients with a limited number of brain metastases. Despite the fact that the seminal studies regarding SRS for brain metastases were largely tissue agnostic, several current national guidelines do not uniformly recommend SRS in thyroid cancer. We therefore investigated oncological outcomes in a cohort of patients with brain metastases from thyroid cancer who received radiotherapy (RT) at our institution as well as those in a nationally representative cancer cohort, the National Cancer Database (NCDB). Materials and Methods: We identified patients with thyroid cancer and brain metastases treated with RT at our institution from 2002 through 2020. For the NCDB cohort, the national database of patients with thyroid cancer was screened on the basis of brain-directed RT or brain metastases. For the institutional cohort, the cumulative risk of local failure (LF), distant intracranial failure, and radiation necrosis were calculated, adjusted for the competing risk of death. Overall survival (OS) in both cohorts was analyzed using the Kaplan-Meier method. Univariate analysis was accomplished via clustered competing risks regression. Results: For the institutional cohort, we identified 33 patients with 212 treated brain metastases. OS was 6.6 months. The 1-year cumulative incidences of LF and distant intracranial failures were 7.0% and 38%, respectively. The 1-year risk of radiation necrosis was 3.3%. In the NCDB cohort, there were 289 patients, and the median survival was 10.2 months. NCDB national practice patterns analysis showed an increasing use of SRS over time in both the entire cohort and the subset of anaplastic patients. Univariate analysis was performed for OS, risk of LF, risk of regional intracranial failure, and risk of radiation necrosis. Conclusions: SRS is a safe, effective, and increasingly utilized treatment for thyroid cancer brain metastases of any histology and should be the standard of care treatment.

Applications of Frameless Image-Guided Robotic Stereotactic Radiotherapy and Radiosurgery in Pediatric Neuro-Oncology: A Systematic Review

BACKGROUND

CyberKnife-based robotic radiosurgery (RRS) is a widely used treatment modality for various benign and malignant tumors of the central nervous system (CNS) in adults due to its high precision, favorable safety profile, and efficacy. Although RRS is emerging in pediatric neuro-oncology, scientific evidence for treatment indications, treatment parameters, and patient outcomes is scarce. This systematic review summarizes the current experience and evidence for RRS and robotic stereotactic radiotherapy (RSRT) in pediatric neuro-oncology.

METHODS

We performed a systematic review based on the databases Ovid Medline, Embase, Cochrane Library, and PubMed to identify studies and published articles reporting on RRS and RSRT treatments in pediatric neuro-oncology. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were applied herein. Articles were included if they described the application of RRS and RSRT in pediatric neuro-oncological patients. The quality of the articles was assessed based on their evidence level and their risk for bias using the original as well as an adapted version of the Newcastle Ottawa Quality Assessment Scale (NOS). Only articles published until 1 August 2021, were included.

RESULTS

A total of 23 articles were included after final review and removal of duplicates. Articles reported on a broad variety of CNS entities with various treatment indications. A majority of publications lacked substantial sample sizes and a prospective study design. Several reports included adult patients, thereby limiting the possibility of data extraction and analysis of pediatric patients. RRS and RSRT were mostly used in the setting of adjuvant, palliative, and salvage treatments with decent local control rates and acceptable short-to-intermediate-term toxicity. However, follow-up durations were limited. The evidence level was IV for all studies; the NOS score ranged between four and six, while the overall risk of bias was moderate to low.

CONCLUSION

Publications on RRS and RSRT and their application in pediatric neuro-oncology are rare and lack high-quality evidence with respect to entity-related treatment standards and long-term outcomes. The limited data suggest that RRS and RSRT could be efficient treatment modalities, especially for children who are unsuitable for surgical interventions, suffer from tumor recurrences, or require palliative treatments. Nevertheless, the potential short-term and long-term adverse events must be kept in mind when choosing such a treatment. Prospective studies are necessary to determine the actual utility of RRS and RSRT in pediatric neuro-oncology.

Adult Posterior Fossa Anaplastic Ependymoma, Case Series and Literature Review

OBJECTIVE

Ependymomas are rare central nervous system tumors. The current treatment strategy is gross total tumor removal. Whether adjuvant therapy will be beneficial is controversial. We retrospectively analyzed 3 cases of World Health Organization (WHO) grade III posterior fossa anaplastic ependymomas treated with different treatment modalities. We aimed to identify possible treatment options for infratentorial WHO grade III anaplastic ependymoma in adults.

METHODS

We performed a retrospective analysis of 3 patients diagnosed with infratentorial anaplastic ependymomas in our institution from 2016 to 2020. The demographic data were documented. This case series of 3 patients does not meet the Department of Health and Human Services definition of research and does not need Institutional Review Board approval. All patients' informed consents have been obtained.

RESULTS

One patient underwent subtotal tumor resection combined with adjuvant radiotherapy and Gamma Knife radiosurgery while the other 2 patients underwent gross total tumor removal combined with Gamma Knife radiosurgery or adjuvant radiotherapy. Tumors recurred in the first patient 20 months later, while the other 2 patents did not develop recurrence. The modified Rankin scale scores of these patients were 1, 0, and 0. All patients are followed up with regular magnetic resonance imaging at our facility.

CONCLUSIONS

The strategy for treating WHO grade III anaplastic ependymomas is controversial, but gross total tumor resection remains the key element. Adjuvant stereotactic radiosurgery after tumor removal might be considered if radiotherapy is not an option. The role of chemotherapy is unclear, and the use of chemotherapy should be tailored to individual patients.

Childhood Cancer: Occurrence, Treatment and Risk of Second Primary Malignancies

Cancer represents the leading cause of disease-related death and treatment-associated morbidity in children with an increasing trend in recent decades worldwide. Nevertheless, the 5-year survival of childhood cancer patients has been raised impressively to more than 80% during the past decades, primarily attributed to improved diagnostic technologies and multiagent cytotoxic regimens. This strong benefit of more efficient tumor control and prolonged survival is compromised by an increased risk of adverse and fatal late sequelae. Long-term survivors of pediatric tumors are at the utmost risk for non-carcinogenic late effects such as cardiomyopathies, neurotoxicity, or pneumopathies, as well as the development of secondary primary malignancies as the most detrimental consequence of genotoxic chemo- and radiotherapy. Promising approaches to reducing the risk of adverse late effects in childhood cancer survivors include high precision irradiation techniques like proton radiotherapy or non-genotoxic targeted therapies and immune-based treatments. However, to date, these therapies are rarely used to treat pediatric cancer patients and survival rates, as well as incidences of late effects, have changed little over the past two decades in this population. Here we provide an overview of the epidemiology and etiology of childhood cancers, current developments for their treatment, and therapy-related adverse late health consequences with a special focus on second primary malignancies.

Image-Guided Robotic Radiosurgery for the Management of Spinal Ependymomas

Background

Ependymomas are rare neoplasms of the central nervous system (CNS), usually localized intracranially and most commonly diagnosed in children. Spinal ependymomas are more frequent in young adults. They are either primary lesions or manifest as disseminated seeding of cranial tumors. Data on the management of spinal ependymoma lesions remain scarce, especially concerning stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). The purpose of this study is to report the treatment outcomes of two institutions using robotic radiosurgery (RRS) for the treatment of spinal ependymomas.

Materials and Methods

All patients with a histopathologically confirmed diagnosis of an ependymoma WHO grade II or III who were treated with RRS for one or more spinal lesions were included in this analysis.

Results

Twelve patients underwent RRS for the treatment of 32 spinal ependymoma lesions between 2005 and 2020. Two patients were below the age of 18 when treated, whereas nine patients (75%) suffered from a primary spinal ependymoma. The median dose was 15 Gy prescribed to a median isodose of 70%, with 27 lesions (84%) receiving a single-session treatment. The local control (LC) after a median follow-up of 56.7 months was 84%. LC rates at 1, 3, and 5 years were 92, 85, and 77%, respectively. The Kaplan-Meier estimated overall survival after 1, 3, and 5 years were 75, 75, and 64%, respectively. Five patients died, all of them suffering from an anaplastic ependymoma, with widespread CNS tumor progression being the reason for death in four patients. The majority of patients (58%) showed a stable neurological status at the last available follow-up. Overall, the treatment was well tolerated.

Conclusion

RRS appears to be a safe and efficient treatment modality for managing primary and secondary spinal ependymal tumors in patients with multiple lesions and local recurrences.

Stereotactic Radiation for Treating Primary and Metastatic Neoplasms of the Spinal Cord

Stereotactic radiation treatment can be used to treat spinal cord neoplasms in patients with either unresectable lesions or residual disease after surgical resection. While treatment guidelines have been suggested for epidural lesions, the utility of stereotactic radiation for intradural and intramedullary malignancies is still debated. Prior reports have suggested that stereotactic radiation approaches can be used for effective tumor control and symptom management. Treatment-related toxicity has been documented in rare subsets of patients, though the incidences of injury are not directly correlated with higher radiation doses. Further studies are needed to assess the factors that influence the risk of radiation-induced myelopathy when treating spinal cord neoplasms with stereotactic radiation, which can include, but may not be limited to, maximum dose, dose-fractionation, irradiated volume, tumor location, histology and treatment history. This review will discuss evidence for current treatment approaches.