The use of stereotactic radiosurgical boost in the treatment of medulloblastomas

Radiosurgery for Pediatric Brain Tumors

The utility of radiosurgery for pediatric brain tumors is not well known. For children, radiosurgery may have an important role for treating unresectable tumors, residual disease, or tumors in the recurrent setting that have received prior radiotherapy. The available evidence demonstrates utility for some children with primary brain tumors resulting in good local control. Radiosurgery can be considered for limited residual disease or focal recurrences. However, the potential toxicities are unique and not insignificant. Therefore, prospective studies need to be performed to develop guidelines for indications and treatment for children and reduce toxicity in this population.

[Radiosurgery as adjuvant treatment of a recurrent adult medulloblastoma. Ultra-early response]

The role of radiosurgery after multimodality treatment of recurrent desmoplastic adult medulloblastoma is analyzed. The ultra-early clinical and pathological response of this tumor to adjunctive radiosurgery is stressed.

Interstitial brachytherapy using stereotactic implanted (125)iodine seeds for recurrent medulloblastoma

AIMS

To evaluate the efficacy of interstitial brachytherapy using (125)iodine ((125)I) seeds for the treatment of recurrent multimodal treated medulloblastoma.

MATERIALS AND METHODS

Between September 1989 and August 2009, 12 patients (female:male=3:9, median age 19 years, range 7-55 years) with 23 recurrent medulloblastomas underwent interstitial brachytherapy using (125)I seeds. Before brachytherapy, all patients underwent microsurgical resection; six patients underwent a combined adjuvant treatment consisting of craniospinal irradiation and chemotherapy; three received craniospinal irradiation alone and two received chemotherapy alone. One patient was treated by surgery alone. The median tumour volume was 4.9ml (range 0.4-44.2ml), the median tumour surface dose 50Gy (range 32-50Gy) and the median implantation time 42 days (range 42-90 days). A median follow-up of 26 months was available (range 5-116 months).

RESULTS

After brachytherapy, nine of 23 tumours (39%) presented a complete remission, nine (39%) a partial remission and five (22%) stable disease on magnetic resonance images. The neurological status improved in six patients and remained unchanged in four. Two patients deteriorated: one developed spinal metastasis and another a treatment-related adverse radiation effect. Ten patients died due to disseminated disease despite local tumour control. The median survival after treatment was 15 months (range 5-68 months).

CONCLUSIONS

Our results show a good response of recurrent medulloblastoma after interstitial brachytherapy. High rates of tumour remission were yielded with low rates of treatment-related morbidity. Thus, (125)I seed brachytherapy should be considered as a treatment option for recurrent medulloblastoma.

Pediatric medulloblastoma: toxicity of current treatment and potential role of protontherapy

Post-operative craniospinal irradiation and systemic chemotherapy are both necessary in the treatment of pediatric medulloblastoma. Late toxicity is a major problem in long term survivors and significantly affects their quality of life. We have systematically reviewed the literature to examine data on late toxicity, specifically focusing on: endocrine function, growth and bone development, neurocognitive development, second cancers, ototoxicity, gynecological toxicity and health of the offspring, cardiac toxicity and pulmonary toxicity. In this paper, we describe qualitatively the kind of detected side effects and, whenever possible, try to assess their incidence and the relative role of craniospinal irradiation (as opposed to other treatments and to the disease itself) in producing them. Subsequently we examine the possible approach to reduce unwanted effects from craniospinal irradiation to target and non-target tissues and we consider briefly the role of hyperfractionation, tomotherapy and IMRT. We describe the characteristics of protontherapy and its potential for non-target tissues toxicity reduction reviewing the existing physical and dosimetric studies and the (still very limited) clinical experiences. Finally we propose intensity modulated spot scanning protontherapy with multiportal simultaneous optimization (IMPT) as a possible tool for dose distribution optimization within different areas of CNS and potential reduction of target tissues toxicity.

Boost Gamma Knife surgery during multimodality management of adult medulloblastoma

OBJECT

The aim of this paper was to determine prognostic factors for adult medulloblastoma treated with boost Gamma Knife surgery (GKS) following resection and craniospinal irradiation.

METHODS

The authors performed a retrospective analysis of 12 adult patients with histologically proven medulloblastoma or supratentorial primitive neuroectodermal tumor who between February 1991 and December 2004 underwent >or=1 sessions of GKS for posttreatment residual or recurrent tumors (6 tumors in each group). Before GKS, all patients had undergone a maximal feasible resection followed by craniospinal irradiation. Nine patients also received systemic chemotherapy. Stereotactic radiosurgery was applied to residual and recurrent posterior fossa tumor as well as to foci of intracranial medulloblastoma metastases. The median time interval from initial diagnosis and resection to the first GKS treatment was 24 months (range 2-37 months). The mean GKS-treated tumor volume was 9.4 cm3 (range 0.5-39 cm3).

RESULTS

Following adjunctive radiosurgery, 5 patients had no evidence of tumor on magnetic resonance (MR) imaging, 3 patients had stable tumor burden on MR imaging, and 4 patients had evidence of tumor progression locally with or without intracranial metastases. All patients with tumor progression died. Eight patients survive with a mean cumulative follow-up of 72.4 months (range 21-152 months). No acute radiation toxicity or delayed radiation necrosis was observed among any of the 12 patients. The majority of patients who achieved tumor eradication (80%) and tumor stabilization (67%) after GKS had residual tumor as the reason for their referral for GKS. The best outcomes were attained in patients with residual disease who were younger, had smaller tumor volumes, had no evidence of metastatic disease, and had received higher cumulative GKS doses.

CONCLUSIONS

Single or multiple GKS sessions were a well-tolerated, feasible, and effective adjunctive treatment for posterior fossa residual or recurrent medulloblastoma as well as intracranial metastatic medulloblastoma in adult patients.

Role of stereotactic radiosurgery and fractionated stereotactic radiotherapy in pediatric brain tumors

Brain tumors are the most common solid tumor in childhood. Surgery and/or fractionated radiotherapy are conventional treatment modalities. Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (FSRT) are advanced radiation therapy techniques that have been frequently used in adults with brain tumors but they are less frequently used in pediatric patients. SRS and FSRT can potentially add to the armamentarium against brain tumors in children. This article will review the role of SRS and FSRT in the management of pediatric brain tumors.

Incidence and severity of postoperative cerebellar mutism syndrome in children with medulloblastoma: a prospective study by the Children's Oncology Group

OBJECT

Cerebellar mutism syndrome (CMS) is a unique postoperative syndrome typically arising 1 to 2 days after resection of a midline posterior fossa tumor; it consists of diminished speech progressing to mutism, emotional lability, hypotonia, and ataxia. Most descriptions have been limited to small institutional series using a retrospective chart review methodology.

METHODS

The authors incorporated a CMS questionnaire in two large clinical trials (Children's Cancer Group [CCG] 9931, treatment for high-risk medulloblastoma/primitive neuroectodermal tumor; and CCG/Pediatric Oncology Group [POG] A9961, treatment for average-risk medulloblastoma) to prospectively survey for incidence, severity, and possible causes of CMS in children with newly diagnosed medulloblastoma. Information pertaining to 450 of the 463 patients enrolled in the studies was available for review (82 patients in CCG 9931, and 368 patients in CCG/POG A9961). Cerebellar mutism syndrome occurred in 107 (24%) of 450 children. Symptom intensity was judged to have been severe in 43%, moderate in 49%, and mild in 8% of these 107 patients. Mutism and ataxia were the features most frequently judged as severe. In both cohorts, preoperative brainstem invasion was the only feature that correlated with risk of CMS. One year after diagnosis, nonmotor speech/language deficits, neurocognitive deficits, and/or ataxia persisted in a significant fraction of patients.

CONCLUSIONS

Nearly one quarter of patients who underwent resection of a medulloblastoma developed symptoms of CMS, of which 92% were judged to be of moderate or severe intensity. Brainstem invasion by tumor was the only risk factor that correlated positively with CMS occurrence; there was a negative correlation with cerebellar hemisphere tumor location. As more radical resections are attempted for medulloblastoma, the potential for increased morbidity must be carefully weighed against prognostic factors, especially in patients with brainstem invasion.

Stereotactic radiation therapy with chemotherapy in the management of recurrent medulloblastomas

Medulloblastomas are highly lethal tumors when they recur. Very few patients survive with conventional treatment. This report documents the preliminary study results of a treatment for recurrent medulloblastomas consisting of stereotactic radiation therapy (SRT) with chemotherapy. Four patients had local recurrence without apparent metastases and 8 patients had metastases with or without local recurrence. Twelve patients with 18 lesions underwent SRT as a single session (n=8) or in a hypofractionated manner (n=10) using a gamma knife or modified linear accelerator. All patients then received systemic chemotherapy. Five patients were treated with one to two sequential courses of high-dose chemotherapy with peripheral blood stem cell transplantation. The reduction in tumor size after SRT was often remarkable. Fourteen of 18 lesions treated disappeared 1-6 months after SRT. Two of 4 patients who had local recurrences without apparent metastasis at the time of SRT are alive without evidence of disease 70 and 72 months after SRT, respectively. In contrast, all 8 patients with metastasis had new lesions either in the spinal canal or on the surface of the brain outside the target area of SRT. Median progression-free survival and overall survival from the time of SRT were 9 and 19 months, respectively. The Kaplan-Meier estimates of PFS and overall survival at 3 years were 17 and 25%, respectively. One patient had brainstem edema after SRT causing bulbar palsy and quadriparesis. One patient died of toxicity of chemotherapy. Our experience suggests that local recurrence can be controlled by SRT with chemotherapy but survival of patients with metastases can not be improved effectively by SRT in conjunction with aggressive chemotherapy.

Review of the prognostic factors in medulloblastoma of children and adults

Medulloblastoma (MB) is rare in adults, accounting for 1% of all primary tumours of the central nervous system (CNS). Based on the assumption that the disease pattern in adults is similar to that in children, adults with medulloblastoma are treated using paediatric protocols. Thanks to progress made in recent years, long-term survival is now possible, with overall ranging from 50 to 60% at 5 years and 40 to 50% at 10 years. However, effective therapy may have devastating long-term side effects, including neuro-psychic and neuro-endocrine sequelae and cognitive dysfunction, especially in young adults. Great interest has been expressed in new biological and molecular prognostic factors, which, combined with clinical variables, may allow a more satisfactory stratification of patients.

Stereotactic radiosurgery for brain tumors in pediatric patients

Brain tumors represent the most common solid tumor in children. Fractionated radiation therapy has been an important treatment modality in the multi-disciplinary management of these tumors. Stereotactic radiosurgery is the precise delivery of a single fraction of radiation and has been an important treatment option for adult brain tumor patients. Although the use of stereotactic radiosurgery in pediatric brain tumors is much less frequent, it represents an important alternative for patients with recurrent, surgically inaccessible or radioresponsive tumors. This article will review the results and logistical issues of this modality in the management of pediatric brain tumors.

Extraaxial primitive neuroectodermal tumor mimicking a vestibular schwannoma: diagnostic and therapeutic difficulties. Report of two cases

Extraaxial cerebellopontine angle (CPA) medulloblastomas and other primitive neuroectodermal tumors (PNETs) are rare tumors. The authors report on two patients with PNETs who presented with progressive audiovestibular symptoms. In each case magnetic resonance (MR) imaging revealed an extraaxial lesion that filled the internal auditory meatus and exhibited the neuroimaging features of a vestibular schwannoma (VS). No high signal intensity was apparent in either the brainstem or adjacent cerebellum on T2-weighted MR images. Surgery with maximum resection (total in one case and subtotal in the other) was performed, followed by craniospinal radiotherapy. One year postoperatively, both patients were free from tumor. A CPA PNET mimicking a VS is a rare entity, the diagnosis of which is important because its treatment differs dramatically from that of VS, including prescribed surgery followed by conventional craniospinal radiotherapy.

Survival of very young children with medulloblastoma (primitive neuroectodermal tumor of the posterior fossa) treated with craniospinal irradiation

PURPOSE

Very young children with medulloblastoma are considered to have a worse prognosis than older children. As radiotherapy remains an important part of the treatment, the adverse prognosis could be due to inadequate radiation treatment rather than biological factors. We analyzed the published literature to examine the impact of radiotherapy on survival in this group.

METHODS AND MATERIALS

A Medline search was performed and we reviewed studies of treatment of medulloblastoma where radiotherapy was delivered using megavoltage equipment and the minimum follow-up allowed the calculation of 5-year survival rates.

RESULTS

Thirty-nine studies were published between 1979 and 1996 with a treatment including craniospinal irradiation and boost to the posterior fossa. Eleven studies comprising 1366 patients analyzed survival by age at diagnosis. Eight of 11 studies showed a worse 5-year survival for the younger patient group which reached statistical significance in two. There is also a suggestion of a higher proportion of children with metastatic disease at presentation in the very young age group. The usual policy in younger children was to give a lower dose of radiotherapy to the craniospinal axis (CSA) and posterior fossa (PF) with reduction of dose in the range of 15 to 25% compared to standard treatment. As dose reduction to the posterior fossa is associated with worse survival and local recurrence is the predominant site of failure, the major determinant of worse survival in very young children with medulloblastoma may be suboptimal radiotherapy. Protocols including postoperative chemotherapy with delayed, omitted, or only local tumor irradiation do not reach survival rates of protocols with standard radiotherapy, also suggesting a continued importance for irradiation.

CONCLUSION

Very young children with medulloblastoma have a worse prognosis than older children. Inadequate radiation dose and technique to the primary tumor region may be a major contributing factor. Current chemotherapeutic regimes alone are not sufficient to compensate for reduced radiation doses and volumes.

Defining the superior border of posterior fossa radiation treatment fields

PURPOSE

Lateral posterior fossa treatment fields are usually defined on traditional simulation films based on bony landmarks. The superior field border, intended to include the apex of the tentorium cerebelli, is frequently difficult to define. While sagittal magnetic resonance imaging (MRI) images or three-dimensional treatment planning tools are good means to locate the tentorial apex, these are not always available. We herein describe a method for locating the tentorial apex based on bony landmarks.

METHODS AND MATERIALS

Midsagittal magnetic resonance images of 53 patients were reviewed. Using a Cartesian grid, the geometric relationship between the tentorial apex and several bony landmarks was assessed. Two lines were defined: the first connected the posterior clinoid and the internal occipital protuberance (AB). The second was perpendicular to the first, included the tentorial apex, and extended from the base of the skull inferiorly to the "crown" of the skull superiorly (DE). Relationships between measurements were made using linear regression and least square fits.

RESULTS

Line DE was within 5 mm of the perpendicular bisector of line AB in 83% (44/53) of patients. The tentorial apex was located within 10 mm of the midpoint of DE in 91% (48/53) of patients.

CONCLUSION

In the majority of patients, the location of the tentorial apex can be estimated based on bony landmarks, to within approximately 10 mm. The technique described is a useful means of estimating the location of the tentorial apex in patients where sagittal MRI imaging or three-dimensional treatment planning tools are not available.

Radiation therapy in tumors of the central nervous system

OBJECTIVES

To review the role of radiation therapy in the management of primary tumors of the central nervous system (CNS).

DATA SOURCES

Book chapters, review articles, and research studies.

CONCLUSIONS

Radiation therapy plays an important role in the management of primary and metastatic tumors of the CNS. Radiation and surgery are combined with curative intent for low-grade tumors. Cranial radiation may be used to prevent brain metastases, and palliative radiation may be used to alleviate symptoms.

IMPLICATIONS FOR NURSING PRACTICE

Helping patients with tumors of the CNS and their family members understand the anticipated side effects of the disease and the therapeutic goals of radiation therapy may help to alleviate anxiety and maintain an optimal quality of life during therapy.