Intensity-modulated radiation therapy in childhood ependymoma

Review and update on pediatric ependymoma

Since our last Special Annual Issue dedicated to the topic of ependymoma in 2009, critical advancements have been made in the understanding of this disease which is largely confined to childhood. In the era of molecular profiling, the prior classification of ependymoma based on histology has become largely irrelevant, with multiple new subtypes of this disease now being described in the newest 2021 WHO CNS Tumor Classification System. Despite our advancements in understanding the underlying biology of these tumors, the mainstays of treatment-gross total surgical resection followed by confocal radiation therapy-have continued to yield the best treatment results across multiple studies and centers. Here, we provide an update on our understanding of the advancements made in tumor biology, surgical, and oncologic management of this disease. As we move into an era of more personalized medicine, it is critical to reflect on our historical understanding of different disease entities, to better understand the future directions of our treatments.

Radiotherapy for rare primary brain tumors

Rare central nervous system tumors are defined by an incidence rate of less than 6 cases per 100 000 individuals a year. It comprises a large panel of entities including medulloblastoma, glioneuronal tumors, solitary fibrous tumors, rare pituitary tumors, ependymal or embryonal tumors. The management of these tumors is not clearly defined and radiotherapy indications should be discussed at a multidisciplinary board. Image-guided and intensity-modulated radiation therapy should be proposed and MRI has a fundamental place in the treatment preparation. To avoid the occurrence of side effects, proton therapy is playing an increasingly role for the treatment of these tumors.

Conformal Radiation Therapy for Ependymoma at Age ≤3 Years: A 25-Year Experience

PURPOSE

Adjuvant radiation therapy (RT) affects survival after surgery for young children (age <3 years) diagnosed with intracranial ependymoma. Conformal photon RT promised to spare normal tissue and was introduced more than 25 years ago to improve outcomes for these vulnerable patients. Long-term results for those first treated with conformal methods provide valuable information and serve as a comparison against newer methods.

METHODS AND MATERIALS

Between 1997 and 2018, 101 patients <3.1-years-old were treated with conformal and intensity modulated photon therapy after definitive surgery for intracranial ependymoma. The median age at RT was 2.1 years and the time from diagnosis to the start of RT was 10 weeks. The extent of resection was gross-total in 82%, and 38% underwent more than 1 attempt at resection. The total prescribed dose was 54 to 59.4 Gy at 1.8 Gy per fraction.

RESULTS

The 10-year event-free and overall survivals were 58.5% ± 5.0% and 72.6% ± 4.5%, respectively, with a median follow-up of 18.4 years (range, 4.2-23.3 years). Tumor progression occurred in 34 patients with a median time of 1.6 years. Death occurred in 34 patients from ependymoma (n = 24), secondary malignancy (n = 6), necrosis (n = 2), shunt failure (n = 1), and anaphylactic reaction (n = 1). Twenty-three patients developed a secondary tumor including 6 cases of fatal high-grade glioma. Of the surviving cohort and those ≥18 years old, 98% obtained a high school diploma, 64% had a current driver's license, 89% were students or employed full or part time, 32% were living independently, and 70% received higher education or training.

CONCLUSIONS

Long-term results of children treated using photon conformal RT after surgery demonstrate that adjuvant RT resulted in long-term disease control and functional independence. These results point to the need for new treatment strategies to improve tumor control and provide investigators hope that newer RT methods will further reduce complications.

Outcome of postoperative radiation therapy for pediatric intracranial ependymoma: a single-institution review

PURPOSE

To report outcome of postoperative radiotherapy (RT) in both new and recurrent grade II and III intracranial ependymomas in children treated at Ramathibodi Hospital.

MATERIALS AND METHODS

Between 2006 and 2017, 24 pediatric intracranial ependymomas treated with postoperative RT were retrospectively reviewed. The median age at diagnosis was 44.5 months (range, 4-165 months). There were 14 (58%) males. Fourteen (58%) patients had infratentorial tumor. The median maximal diameter of tumor at diagnosis was 4.45 cm (range, 2.2-10 cm). Fourteen (58%) patients had anaplastic tumor. Gross total resections were performed in 14 (58%) patients. The median prescribed dose was 54 Gy (range, 45-60 Gy). The median total treatment time was 43 days (range, 37-78 days).

RESULTS

The median clinical follow-up time was 44.5 months (range, 1-146 months). There were nine recurrences, five of which occurred at the primary tumor site. The estimated 5-year progression-free survival rate was 56%. The estimated 5-year overall survival rate was 75%. Extent of resection was the only factor associated with improved progression-free survival and overall survival after univariate testing. Six from nine patients with recurrent diseases underwent further surgery or further RT. These six patients had better median overall survival than the three who did not. Acute complication was mostly transient and tolerable. No late radiation effect was found.

CONCLUSIONS

Postoperative radiation is an effective treatment. GTR is associated with better PFS and OS. Aggressive salvage local treatments for recurrent patients can result in good overall survival. Longer follow-up is needed in account for late relapse.

Central nervous system ependymoma: clinical implications of the new molecular classification, treatment guidelines and controversial issues

Ependymoma is an uncommon neuroepithelial tumor that may arise anywhere within the neuroaxis, both in children and in adults. It has been classically graded upon histopathological features, yet with limited clinical utility. Recently, DNA methylation profiling has provided a novel classification of ependymoma in nine molecular subgroups. This stratification method harbors prognostic value with supratentorial RELA-fusion and posterior fossa group A tumors showing a significantly shorter survival compared to the rest. Currently, the treatment of choice involves maximal safe resection and, in cases of residual disease, adjuvant conformal radiotherapy. Second-look surgery is also a feasible and recommended option for incompletely resected tumors. The role of chemotherapy is not yet established and can be considered in infants and children with relapsing disease or prior to re-intervention. Although targeted agents do not seem to play a role as adjuvant therapy, they are currently being tested for recurrent disease.

Low-Grade Glioma Radiotherapy Treatment and Trials

Low-grade gliomas represent an important class of primary brain tumors. They account for approximately 20% of primary brain tumors and typically present in the fourth decade of life. Standard management gliomas involves observation, surgery, chemotherapy, and/or radiotherapy. Treatment decisions are based on many factors including prognostic molecular markers, potential benefits of increased progression-free survival, and potential long-term treatment complications. Recent studies have improved our understanding regarding therapeutic interventions. This review provides an overview of low-grade glioma and discusses the roles of radiation therapy. We discuss advances in techniques and recent and ongoing radiation therapy-related clinical trials for low-grade gliomas.

Second cancer risk after radiation therapy of ependymoma using the flattening filter free irradiation mode of a linear accelerator

Pediatric patients suffering from ependymoma are usually treated with cranial or craniospinal three‐dimensional (3D) conformal radiotherapy (3DCRT). Intensity‐modulated techniques spare dose to the surrounding tissue, but the risk for second malignancies may be increased due to the increase in low‐dose volume. The aim of this study is to investigate if the flattening filter free (FFF) mode allows reducing the risk for second malignancies compared to the mode with flattening filter (FF) for intensity‐modulated techniques and to 3DCRT. A reduction of the risk would be advantageous for treating pediatric ependymoma. 3DCRT was compared to intensity‐modulated radiation therapy (IMRT) and volumetric‐modulated arc therapy (VMAT) with and without flattening filter. Dose–volume histograms (DVHs) were compared to evaluate the plan quality and used to calculate the excess absolute risk (EAR) to develop second cancer in the brain. Dose verification was performed with a two‐dimensional (2D) ionization chamber array and the out‐of‐field dose was measured with an ionization chamber to determine the EAR in peripheral organs. Delivery times were measured. Both VMAT and IMRT achieved similar plan quality in terms of dose sparing in the OAR and higher PTV coverage as compared to 3DCRT. Peripheral dose in low‐dose region, which is proportional to the EAR in organs located in this region, for example, gonads, bladder, or bowel, could be significantly reduced using FFF. The lowest peripheral EAR and lowest delivery times were hereby achieved with VMAT_FFF. The EAR calculated based on DVH in the brain could not be reduced using FFF mode. VMAT_FFF improved the target coverage and homogeneity and kept the dose in the OAR similar compared to 3DCRT. In addition, delivery times were significantly reduced using VMAT_FFF. Therefore, for radiotherapy of ependymoma patients, VMAT_FFF may be considered advantageous for the combination of Elekta Synergy linac and Oncentra External Beam planning system used in this study.

Medulloblastoma: From Molecular Subgroups to Molecular Targeted Therapies

Brain tumors are the leading cause of cancer-related death in children, and medulloblastoma (MB) is the most common malignant pediatric brain tumor. Advances in surgery, radiation, and chemotherapy have improved the survival of MB patients. But despite these advances, 25-30% of patients still die from the disease, and survivors suffer severe long-term side effects from the aggressive therapies they receive. Although MB is often considered a single disease, molecular profiling has revealed a significant degree of heterogeneity, and there is a growing consensus that MB consists of multiple subgroups with distinct driver mutations, cells of origin, and prognosis. Here, we review recent progress in MB research, with a focus on the genes and pathways that drive tumorigenesis, the animal models that have been developed to study tumor biology, and the advances in conventional and targeted therapy.

Patterns of relapse for children with localized intracranial ependymoma

We examined patterns of relapse and prognostic factors in children with intracranial ependymoma. Records of 82 children diagnosed with localized intracranial ependymoma were reviewed. 52% first presented to our institution after relapse. Median age at initial diagnosis was 4 years (range 0-18 years). Gender was 55% male. Initial tumor location was infratentorial in 71% and supratentorial in 29%. Histology was WHO Grade II in 32% and Grade III in 68%. As part of definitive management, 99% had surgery, 70% received RT (26% 2D/3D-conformal RT[CRT], 22% intensity-modulated RT [IMRT], 22% proton), and 37% received chemotherapy. Median follow-up was 4.6 years (range 0.2-32.9). Overall, 74% of patients relapsed (50% local, 17% distant, 7% local + distant) at a median 1.5 (range 0.1-17.5) years. Five-year OS and FFS for patients presenting prior to relapse are 70% (95% confidence interval [CI], 50-83%) and 48% (95% CI 30-64%), respectively. On log-rank, superior overall survival (OS) was demonstrated for gross total resection (p = 0.03). Superior failure-free survival (FFS) was demonstrated for age < 5 years (p = 0.04). No difference in OS or FFS was found between 2D/3D-CRT versus IMRT/proton (p > 0.05). On multivariate analysis, age ≤ 5 was independently associated with a lower risk of death and failure versus older patients (p < 0.05). Contrary to previous reports, young age may not be a poor prognostic factor in patients who can tolerate intensive treatment. Future studies examining patients stratified by clinical and molecular attributes are warranted.

Correlation of Acute and Late Brainstem Toxicities With Dose-Volume Data for Pediatric Patients With Posterior Fossa Malignancies

PURPOSE

Radiation-induced brainstem toxicity after treatment of pediatric posterior fossa malignancies is incompletely understood, especially in the era of intensity modulated radiation therapy (IMRT). The rates of, and predictive factors for, brainstem toxicity after photon RT for posterior fossa tumors were examined.

METHODS AND MATERIALS

After institutional review board approval, 60 pediatric patients treated at our institution for nonmetastatic infratentorial ependymoma and medulloblastoma with IMRT were included in the present analysis. Dosimetric variables, including the mean and maximum dose to the brainstem, the dose to 10% to 90% of the brainstem (in 10% increments), and the volume of the brainstem receiving 40, 45, 50, and 55 Gy were recorded for each patient. Acute (onset within 3 months) and late (>3 months of RT completion) RT-induced brainstem toxicities with clinical and radiographic correlates were scored using Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

Patients aged 1.4 to 21.8 years underwent IMRT or volumetric arc therapy postoperatively to the posterior fossa or tumor bed. At a median clinical follow-up period of 2.8 years, 14 patients had developed symptomatic brainstem toxicity (crude incidence 23.3%). No correlation was found between the dosimetric variables examined and brainstem toxicity. Vascular injury or ischemia showed a strong trend toward predicting brainstem toxicity (P=.054). Patients with grade 3 to 5 brainstem toxicity had undergone treatment to significant volumes of the posterior fossa.

CONCLUSION

The results of the present series demonstrate a low, but not negligible, risk of brainstem radiation necrosis for pediatric patients with posterior fossa malignancies treated with IMRT. No specific dose-volume correlations were identified; however, modern treatment volumes might help limit the incidence of severe toxicity. Additional work investigating inherent biologic sensitivity might also provide further insight into this clinical problem.

Advances in Management of Pediatric Ependymomas

Ependymomas are a heterogeneous group of neuroepithelial tumors of children and adults. In pediatric cases, the standard of care has long consisted of neurosurgical resection to the greatest extent acceptable followed by adjuvant involved field irradiation. Complete macroscopic surgical resection has remained the only consistent clinical variable known to improve survival. Adjuvant chemotherapy has yet to predictably affect outcome, possibly due to the molecular heterogeneity of histologically similar tumors. The administration of chemotherapy subsequently remains limited to clinical trials. However, recent comprehensive genomic, transcriptomic, and epigenetic interrogations of ependymomas have uncovered unique molecular characteristics and subtypes that correlated with clinical features such as age, neuroanatomical location, and prognosis. These findings represent a potential paradigm shift and provide a biologic rationale for targeted therapeutic strategies and risk-adapted administration of conventional treatment modalities. In this review, we focus on intracranial WHO grade II and III ependymoma of children and discuss conventional management strategies, followed by recent biologic findings and novel therapeutics currently under investigation.

Ependymoma: a heterogeneous tumor of uncertain origin and limited therapeutic options

Ependymomas are tumors that typically occur with an age-based site preference, with adults harboring supratentorial and spinal tumors and pediatric tumors being mainly in the posterior fossa. Despite their similar histologic appearance, the prognosis varies significantly by age and tumor location, with a better prognosis in increasing age. The mainstay of treatment remains surgical excision with or without radiation therapy as the tumor biology is poorly understood and chemotherapy is generally considered to be ineffective. More recently, molecular biology data have increased our understanding of the genetic and epigenetic changes that drive these tumors, but still it will take a lot of effort to find effective chemotherapeutic regimens. Currently, we are trying to define a subset of tumors, for which radiation therapy can be avoided.

Timing of adjuvant radiotherapy and treatment outcome in childhood ependymoma

BACKGROUND

Several trials incorporating adjuvant focal RT for treatment of young children with ependymoma have demonstrated improved survival with acceptable adverse effects. The optimal timing of RT administration is, however, unknown.

PROCEDURE

A retrospective review of territory-wide database was performed to identify pediatric patients with ependymoma diagnosed between 1995 and 2011. OS and EFS were compared between patients receiving upfront RT (<150 days of diagnosis), delayed RT (≥150 days of diagnosis), or no RT.

RESULTS

Thirty-one patients with intracranial ependymoma were identified. Median age was 3.5 years and 14 (45%) were male. Primary tumor was supratentorial in 10 (32%) and infratentorial in 21 (68%). All patients underwent initial surgery, with gross-total resection (GTR) in 27 (87%). Twelve (39%) received upfront RT, 10 (32%) had delayed RT and 9 (29%) had no RT. During the study period, there were 11 relapses (35%) and 10 deaths (32%). Five-year OS was 69.9% and 5yr-EFS was 49.3%. In univariate analysis, GTR led to improved OS (P < 0.001) and EFS (P = 0.004); superior OS and EFS was observed in patients who received RT when compared with those without (P = 0.018 and 0.011, respectively). Upfront RT also resulted in better OS and EFS than delayed RT (P = 0.049 and 0.014, respectively). No significant effect on survival was observed with age, sex, tumor location, RT dosage, and protocol used. In multivariate analysis, GTR significantly improved OS (P = 0.002) and EFS (P = 0.004).

CONCLUSIONS

Our results support the early initiation of adjuvant RT in the multi-modal management of pediatric ependymomas.

A systematic review of treatment outcomes in pediatric patients with intracranial ependymomas

OBJECT

Ependymoma is the third most common primary brain tumor in children. Tumors are classified according to the WHO pathological grading system. Prior studies have shown high levels of variability in patient outcomes within and across pathological grades. The authors reviewed the results from the published literature on intracranial ependymomas in children to describe clinical outcomes as they relate to treatment modality, associated mortality, and associated progression-free survival (PFS).

METHODS

A search of English language peer-reviewed articles describing patients 18 years of age or younger with intracranial ependymomas yielded data on 182 patients. These patients had undergone treatment for ependymoma with 1 of 5 modalities: 1) gross-total resection (GTR), 2) GTR as well as external beam radiation therapy (EBRT), 3) subtotal resection (STR), 4) STR as well as EBRT, or 5) radiosurgery. Mortality and outcome data were analyzed for time to tumor progression in patients treated with 1 of these 5 treatment modalities.

RESULTS

Of these 182 patients, 69% had supratentorial ependymomas and 31% presented with infratentorial lesions. Regardless of tumor location or pathological grade, STR was associated with the highest rates of mortality. In contrast, GTR was associated with the lowest rates of mortality, the best overall survival, and the longest PFS. Children with WHO Grade II ependymomas had lower mortality rates when treated more aggressively with GTR. However, patients with WHO Grade III tumors had slightly better survival outcomes after a less aggressive surgical debulking (STR+EBRT) when compared with GTR.

CONCLUSIONS

Mortality, PFS, and overall survival vary in pediatric patients with intracranial ependymomas. Pathological classification, tumor location, and method of treatment play a role in outcomes. In this study, GTR was associated with the best overall and PFS rates. Patients with WHO Grade II tumors had better overall survival after GTR+EBRT and better PFS after GTR alone. Patients with WHO Grade III tumors had better overall survival after STR+EBRT. Patients with infratentorial tumors had improved overall survival compared with those with supratentorial tumors. Progression-free survival was best in those patients with infratentorial tumors following STR+EBRT. Consideration of all of these factors is important when counseling families on treatment options.

Intensity-modulated radiotherapy (IMRT) in pediatric low-grade glioma

BACKGROUND

The objective of this study was to evaluate local control and patterns of failure in pediatric patients with low-grade glioma (LGG) who received treatment with intensity-modulated radiation therapy (IMRT).

METHODS

In total, 39 children received IMRT after incomplete resection or disease progression. Three methods of target delineation were used. The first was to delineate the gross tumor volume (GTV) and add a 1-cm margin to create the clinical target volume (CTV) (Method 1; n = 19). The second was to add a 0.5-cm margin around the GTV to create the CTV (Method 2; n = 6). The prescribed dose to the GTV was the same as dose to the CTV for both Methods 1 and 2 (median, 50.4 grays [Gy]). The final method was dose painting, in which a GTV was delineated with a second target volume (2TV) created by adding 1 cm to the GTV (Method 3; n = 14). Different doses were prescribed to the GTV (median, 50.4 Gy) and the 2TV (median, 41.4 Gy).

RESULTS

The 8-year progression-free and overall survival rates were 78.2% and 93.7%, respectively. Seven failures occurred, all of which were local in the high-dose (≥95%) region of the IMRT field. On multivariate analysis, age ≤5 years at time of IMRT had a detrimental impact on progression-free survival.

CONCLUSIONS

IMRT provided local control rates comparable to those provided by 2-dimensional and 3-dimensional radiotherapy. Margins ≥1 cm added to the GTV may not be necessary, because excellent local control was achieved by adding a 0.5-cm margin (Method 2) and by dose painting (Method 3).

Retrospective analysis of treatment outcome of pediatric ependymomas in Korea: analysis of Korean multi-institutional data

We analyzed the treatment outcomes of intracranial ependymomas in Korean children aged <18 years. Data for 96 patients were collected from five hospitals. Survival rates were calculated using the Kaplan-Meier method. Log-rank tests for univariate analyses and Cox regression model for multivariate analysis were conducted to identify prognostic factors for survival. The median age of the patients was 4 years (range, 0.3-17.9 years). The median follow-up was 55 months (range, 2-343 months). Age <3 years was an important factor for selecting adjuvant therapy after surgery. Among children aged <3 and ≥ 3 years, adjuvant radiotherapy (RT) was applied to 55 and 84 %, respectively, and adjuvant chemotherapy to 52 and 10 %, respectively. The 5 year local progression-free survival (LPFS), disease-free survival (DFS), and overall survival (OS) rates were 54, 52, and 79 %, respectively. Gross total resection was the most significant prognostic factor for all survival endpoints. Age ≥ 3 years and RT were significant prognostic factors for superior LPFS and DFS. However, the significance of age was lost in multivariate analysis for DFS. LPFS, DFS, and OS were superior in patients who started RT within 44 days after surgery (the median time) than in patients who started RT later in the patients aged ≥ 3 years. Postoperative RT was a strong prognostic factor for intracranial ependymomas. Our results suggest that early use of RT is an essential component of treatment, and should be considered in young children.

Helical tomotherapy in the treatment of pediatric malignancies: a preliminary report of feasibility and acute toxicity

Background

Radiation therapy plays a central role in the management of many childhood malignancies and Helical Tomotherapy (HT) provides potential to decrease toxicity by limiting the radiation dose to normal structures. The aim of this article was to report preliminary results of our clinical experience with HT in pediatric malignancies.

Methods

In this study 66 consecutive patients younger than 14 years old, treated with HT at our center between January 2006 and April 2010, have been included. We performed statistical analyses to assess the relationship between acute toxicity, graded according to the RTOG criteria, and several clinical and treatment characteristics such as a dose and irradiation volume.

Results

The median age of patients was 5 years. The most common tumor sites were: central nervous system (57%), abdomen (17%) and thorax (6%). The most prevalent histological types were: medulloblastoma (16 patients), neuroblastoma (9 patients) and rhabdomyosarcoma (7 patients). A total of 52 patients were treated for primary disease and 14 patients were treated for recurrent tumors. The majority of the patients (72%) were previously treated with chemotherapy. The median prescribed dose was 51 Gy (range 10-70 Gy). In 81% of cases grade 1 or 2 acute toxicity was observed. There were 11 cases (16,6%) of grade 3 hematological toxicity, two cases of grade 3 skin toxicity and one case of grade 3 emesis. Nine patients (13,6%) had grade 4 hematological toxicity. There were no cases of grade 4 non-hematological toxicities. On the univariate analysis, total dose and craniospinal irradiation (24 cases) were significantly associated with severe toxicity (grade 3 or more), whereas age and chemotherapy were not. On the multivariate analysis, craniospinal irradiation was the only significant independent risk factor for grade 3-4 toxicity.

Conclusion

HT in pediatric population is feasible and safe treatment modality. It is characterized by an acceptable level of acute toxicity that we have seen in this highly selected pediatric patient cohort with clinical features of poor prognosis and/or aggressive therapy needed. Despite of a dosimetrical advantage of HT technique, an exhaustive analysis of long-term follow-up data is needed to assess late toxicity, especially in this potentially sensitive to radiation population.

[Intracranial ependymomas: retrospective study of 16 cases]

PURPOSE

To report the epidemiological, clinical aspects and therapeutic results of intracranial ependymomas in Morocco.

PATIENTS AND METHODS

Our retrospective study concerned 16 cases of intracranial ependymomas, treated from January 1995 to December 2002 at the radiotherapy department of Ibn Rochd Hospital of Casablanca, Morocco.

RESULTS

The average age was 15 years and complete surgery was possible in two cases. All the patients received cranial radiotherapy, combined with chemotherapy in six cases. Overall survival and progression-free survival at 5 years were respectively 50% and 31%. Eleven patients had local recurrence after an average period of 21 months. Progression-free survival at 5 years was better if complete resection: 100% vs. 28.6% in cases of incomplete resection, and depending on the histological type with 50% for classic ependymomas and 16.6% for anaplastic.

CONCLUSION

Ependymomas are rare tumors and complete resection is the standard treatment followed by postoperative radiotherapy. The place of chemotherapy remains to be defined.

Intensity modulated radiation therapy or stereotactic fractionated radiotherapy for infratentorial ependymoma in children: a multicentric study

This study was to evaluate the treatment dosimetry, efficacy and toxicity of intensity modulated radiation therapy (IMRT) and fractionated stereotactic radiotherapy (FSRT) in the management of infratentorial ependymoma. Between 1999 and 2007, seven children (median age, 3.1 years) with infratentorial ependymoma were planned with either IMRT (3 patients) or SFRT (4 patients), the latter after conventional posterior fossa irradiation. Two children underwent gross total resection. Median prescribed dose was 59.4 Gy (range, 55.8-60). The median follow-up for surviving patients was 4.8 years (range, 1.3-8). IMRT (median dose, 59.4 Gy) and FSRT (median dose, 55.8 Gy) achieved similar optimal target coverage. Percentages of maximum doses delivered to the cochleae (59.5 vs 85.0% Gy; P = 0.05) were significantly inferior with IMRT, when compared to FSRT planning. Percentages of maximum doses administered to the pituitary gland (38.2 vs 20.1%; P = 0.05) and optic chiasm (38.1 vs 14.1%; P = 0.001) were, however, significantly higher with IMRT, when compared to FSRT planning. No recurrences were observed at the last follow-up. The estimated 3-year progression-free survival and overall survival were 87.5 and 100%, respectively. No grade >1 acute toxicity was observed. Two patients presented late adverse events (grade 2 hypoacousia) during follow-up, without cognitive impairment. IMRT or FSRT for infratentorial ependymomas is effective and associated with a tolerable toxicity level. Both treatment techniques were able to capitalize their intrinsic conformal ability to deliver high-dose radiation. Larger series of patients treated with these two modalities will be necessary to more fully evaluate these delivery techniques.

Dosimetric effect of setup motion and target volume margin reduction in pediatric ependymoma

PURPOSE

Quantify the dosimetric effect of inter- and intrafractional motion on intensity-modulated radiation therapy (IMRT) and three-dimensional (3D) planning via changes in the generalized equivalent uniform dose (gEUD), predicted tumor control probability (TCP) and normal tissue complication probability (NTCP) for pediatric ependymoma.

METHODS AND MATERIALS

Twenty patients treated between 1998 and 2002 with a 3D plan (CTV = 1 cm, PTV = 5 mm) were selected. Two IMRT plans were created for the 1 cm CTV (PTV = 5 mm and PTV = 0 mm), and a third IMRT plan for a 5 mm CTV (PTV = 0 mm). Direct simulation with inter- and intrafractional motion was performed for 3D and IMRT plans based on daily pre and post-treatment cone beam CT information obtained from 20 well-matched patients (age, supine/prone, use of GA) on a localization protocol. Calculated TCP, NTCP, Conformity Index (CI), and predictive IQ were compared.

RESULTS

IMRT improved the calculated TCP by 2.8+/-2.8 vs. 3D (p<0.001). Inter- and intrafractional motion results in a TCP loss of 0.4+/-0.7 (p=0.02) and 0.0+/-0.1 (p=0.14) for the IMRT plan with PTV = 0 mm. Mean NTCP for 3D and IMRT with PTV = 5 mm, PTV = 0 mm, and CTV = 5 mm for the cochlea was: 66.6, 29.4, 8.7. Mean NTCP change due to motion was <5%. CI was 0.70+/-0.06 for IMRT and 0.5+/-0.10 for 3D. Predictive IQ was 10.0+/-10.3 points higher for IMRT vs. 3D.

CONCLUSIONS

IMRT improves calculated TCP vs. 3D. Daily localization can allow for a safe reduction in the PTV margin, while maintaining target coverage; reducing the CTV margin can further reduce NTCP and may reduce future side-effects.

Ependymoma: an update

The authors provide an update on most issues related to biology, diagnosis, and treatment of children with ependymoma based on a literature review. Ependymoma is the third most common brain tumor in children and overall survival ranges from 24% to 75% at 5 years. The extent of surgical resection remains the principal risk factor that clearly influences outcome. The influence of age, location, grade, or stage has proved to be more controversial. Current standard therapy includes surgical resection and radiotherapy. Chemotherapy has a role in infants to avoid/delay radiotherapy and can be helpful to improve resectability. About half of patients will experience relapse, and outcome is dismal. New radiation modalities, reirradiation, chemotherapy, or targeted agents have been tested with promising results. Results of multi-institutional clinical trials are awaited to determine the best first-line treatment, while results of early phase I/ II trials will explore directed therapies based on new biologic factors.

Intensity-modulated and 3D-conformal radiotherapy for whole-ventricular irradiation as compared with conventional whole-brain irradiation in the management of localized central nervous system germ cell tumors

PURPOSE

To compare the sparing potential of cerebral hemispheres with intensity-modulated radiotherapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for whole-ventricular irradiation (WVI) and conventional whole-brain irradiation (WBI) in the management of localized central nervous system germ cell tumors (CNSGCTs).

METHODS AND MATERIALS

Ten cases of patients with localized CNSGCTs and submitted to WVI by use of IMRT with or without a "boost" to the primary lesion were selected. For comparison purposes, similar treatment plans were produced by use of 3D-CRT (WVI with or without boost) and WBI (opposed lateral fields with or without boost), and cerebral hemisphere sparing was evaluated at dose levels ranging from 2 Gy to 40 Gy.

RESULTS

The median prescription dose for WVI was 30.6 Gy (range, 25.2-37.5 Gy), and that for the boost was 16.5 Gy (range, 0-23.4 Gy). Mean irradiated cerebral hemisphere volumes were lower for WVI with IMRT than for 3D-CRT and were lower for WVI with 3D-CRT than for WBI. Intensity-modulated radiotherapy was associated with the lowest irradiated volumes, with reductions of 7.5%, 12.2%, and 9.0% at dose levels of 20, 30, and 40 Gy, respectively, compared with 3D-CRT. Intensity-modulated radiotherapy provided statistically significant reductions of median irradiated volumes at all dose levels (p = 0.002 or less). However, estimated radiation doses to peripheral areas of the body were 1.9 times higher with IMRT than with 3D-CRT.

CONCLUSIONS

Although IMRT is associated with increased radiation doses to peripheral areas of the body, its use can spare a significant amount of normal central nervous system tissue compared with 3D-CRT or WBI in the setting of CNSGCT treatment.

Survival following treatment for intracranial ependymoma: a review

The actual definition of survival rates following treatment for intracranial ependymomas is substantially influenced by the strict interaction among different factors. Age, location, and grading, for example, act together, negatively influencing the prognosis of younger children also invariably influenced by the more demanding role of surgery and the still limited use, up to recently, of radiotherapy under 3 years of age. In the same direction, the worse prognosis in most series of infratentorial ependymomas if compared with their supratentorial counterpart should be cautiously considered, midline posterior fossa tumors having completely different implications from those originating or predominantly extending to the cerebellopontine angle, where the extent of surgery has more invariably to compare with patients' quality of life. New radiotherapic regimens and their applications in infancy are promisingly demonstrating an improvement of present prognostic criteria, with the limit of still insufficient information on their long-term secondary effects. Similarly, molecular biology research studies, though still in their preclinical stage, are prompting to change the concept of a substantially chemoresistant tumor helping to stratify these lesions with the final aim of targeted pharmacological therapies. In the present review paper, we investigated singularly the role that the more commonly considered prognostic factors have had in the literature on survival of children affected by intracranial ependymomas, trying to elucidate their cumulative effect on the actual knowledge of this issue.

The history of ependymoma management

INTRODUCTION

The ependymomas are relatively not a common tumor. However, most clinicians agree that the radical removal of the tumor is the most important prognostic factor.

MORBIDITY OF TREATMENT

Tumor removal was not sufficient before the era of magnetic resonance imaging (MRI) and resulted in a considerable operative morbidity and mortality. As the microneurosurgical techniques and microsurgical anatomy become popular and the MRI provide more detailed anatomical information preoperatively, radical removal of this complex and complicated tumor can be more feasible. In childhood ependymoma, the treatment-related morbidity and mortality can be the special issues, which can modify the policy of management safe tumor removal and minimal adjuvant treatment, which are extremely important.

RADIATION THERAPY

Radiation treatment has been the option for disseminated disease and residual tumor. With the advancement of detailed MR anatomical information, safer and more delicate radiation becomes possible with newer radiation modalities, three-dimensional conformal radiotherapy, intensity modulating radiotherapy, and tomotherapy.

PROGNOSTIC FACTORS

Although many clinicians believe that the ependymomas are inheritably chemoresistant, the new targets for the treatment are under investigation or clinically tried. Also, the genetic alterations of ependymoma are developing and might be a promising target.

CONCLUSION

The surgical techniques and assistant modalities for tumor removal are still advancing. So, the outcome of ependymoma is still improving. Unfortunately, newer treatment modalities, such as new chemotherapeutic agent and gene modification agent, are still not promising. The history of ependymoma management is still in progress.

Three-dimensional conformal radiation therapy for ependymoma

INTRODUCTION

The application of conformal radiation therapy in the treatment of pediatric ependymoma is a success story resulting from advances in radiation therapy planning and delivery. These advances occurred at a time when clinical trial results confirmed that radiotherapy avoidance strategies were unsuccessful.

DISCUSSION

Investigators have been keen to confirm the promise of newer radiation therapy methods even for the youngest children. When preliminary results suggested that high-dose focal irradiation could be safely administered through systematic targeting and that cognitive function could be preserved, investigators moved to include conformal therapy in the frontline management of children regardless of age. The results with postoperative conformal radiation therapy were further enhanced when neurosurgeons increased the rate of gross-total resection and recognized that second surgery could be safely accomplished after incomplete initial resection. With more than a decade of experience, the role of conformal radiation therapy in the treatment of childhood ependymoma has been firmly established as investigators consider new trials to increase disease control and improve functional outcomes.

Intensity modulated radiotherapy (IMRT) in the treatment of children and adolescents--a single institution's experience and a review of the literature

Background

While IMRT is widely used in treating complex oncological cases in adults, it is not commonly used in pediatric radiation oncology for a variety of reasons. This report evaluates our 9 year experience using stereotactic-guided, inverse planned intensity-modulated radiotherapy (IMRT) in children and adolescents in the context of the current literature.

Methods

Between 1999 and 2008 thirty-one children and adolescents with a mean age of 14.2 years (1.5 - 20.5) were treated with IMRT in our department. This heterogeneous group of patients consisted of 20 different tumor entities, with Ewing's sarcoma being the largest (5 patients), followed by juvenile nasopharyngeal fibroma, esthesioneuroblastoma and rhabdomyosarcoma (3 patients each). In addition a review of the available literature reporting on technology, quality, toxicity, outcome and concerns of IMRT was performed.

Results

With IMRT individualized dose distributions and excellent sparing of organs at risk were obtained in the most challenging cases. This was achieved at the cost of an increased volume of normal tissue receiving low radiation doses. Local control was achieved in 21 patients. 5 patients died due to progressive distant metastases. No severe acute or chronic toxicity was observed.

Conclusion

IMRT in the treatment of children and adolescents is feasible and was applied safely within the last 9 years at our institution. Several reports in literature show the excellent possibilities of IMRT in selective sparing of organs at risk and achieving local control. In selected cases the quality of IMRT plans increases the therapeutic ratio and outweighs the risk of potentially increased rates of secondary malignancies by the augmented low dose exposure.

Conformal radiotherapy after surgery for paediatric ependymoma: a prospective study

BACKGROUND

Therapy for ependymoma includes aggressive surgical intervention and radiotherapy administered by use of methods that keep the risk of side-effects to a minimum. We extended this treatment approach to include children under the age of 3 years with the aim of improving tumour control.

METHODS

Between July 11, 1997, and Nov 18, 2007, 153 paediatric patients (median age 2.9 years [range 0.9-22.9 months]) with localised ependymoma were treated. 85 patients had anaplastic ependymoma; the tumours of 122 were located in the infratentorial region, and 35 had received previous chemotherapy. Patients received conformal radiotherapy after definitive surgery (125 patients had undergone gross total, 17 near total, and 11 subtotal resection). Doses of 59.4 Gy (n=131) or 54.0 Gy (n=22) were prescribed to a 10 mm margin around the target volume. Disease control, patterns of failure, and complications were recorded for patients followed over 10 years. Overall survival, event-free survival (EFS), cumulative incidence of local recurrences, and cumulative incidence of distant recurrences were assessed. Variables considered included tumour grade, tumour location, ethnic origin, sex, age when undergoing conformal radiotherapy, total radiotherapy dose, number of surgical procedures, surgery extent, and preradiotherapy chemotherapy.

FINDINGS

After a median follow-up of 5.3 years (range 0.4-10.4), 23 patients had died and tumour progression noted in 36, including local (n=14), distant (n=15), and combined failure (n=7). 7-year local control, EFS, and overall survival were 87.3% (95% CI 77.5-97.1), 69.1% (56.9-81.3), and 81.0% (71.0-91.0), respectively. The cumulative incidences of local and distant failure were 16.3% (9.6-23.0) and 11.5% (5.9-17.1), respectively. In the 107 patients treated with immediate postoperative conformal radiotherapy (without delay or chemotherapy), 7-year local control, EFS, and overall survival were 88.7% (77.9-99.5), 76.9% (63.4-90.4), and 85.0% (74.2-95.8), respectively; the cumulative incidence of local and distant failure were 12.6% (5.1-20.1), and 8.6% (2.8-14.3), respectively. The incidence of secondary malignant brain tumour at 7 years was 2.3% (0-5.6) and brainstem necrosis 1.6% (0-4.0). Overall survival was affected by tumour grade (anaplastic vs differentiated: HR 3.98 [95% CI 1.51-10.48]; p=0.0052), extent of resection (gross total vs near total or subtotal: 0.16 [0.07-0.37]; p<0.0001), and ethnic origin (non-white vs white: 3.0 [1.21-7.44]; p=0.018). EFS was affected by tumour grade (anaplastic vs differentiated: 2.52 [1.2705.01]; p=0.008), extent of resection (gross total vs near total or subtotal: 0.20 [0.11-0.39]; p<0.0001]), and sex (male vs female: 2.19 [1.03-4.66]; p=0.042). Local failure was affected by extent of resection (gross total vs near total or subtotal: 0.16 [0.067-0.38]; p<0.0001), sex (male vs female: 3.85 [1.10-13.52]; p=0.035), and age (<3 years vs >/=3 years: 3.25 [1.30-8.16]; p=0.012). Distant recurrence was only affected by tumour grade (anaplastic vs differentiated: 4.1 [1.2-14.0]; p=0.017).

INTERPRETATION

Treatment of ependymoma should include surgery with the aim of gross-total resection and conformal, high-dose, postoperative irradiation. Future trials might consider treatment stratification based on sex and age.

The management of completely resected childhood intracranial ependymoma: the argument for observation only

INTRODUCTION

The management of children with completely resected intracranial ependymomas is controversial. We favor deferring adjuvant radiotherapy in low-risk patients, whereas others recommend radiotherapy.

REVIEW

This article reviews the available evidence for and against deferring radiotherapy in children with low-risk completely resected childhood ependymomas.