Contemporary management of adult and pediatric brain stem gliomas

Genomic alterations underlying spinal metastases in pediatric H3K27M-mutant pineal parenchymal tumor of intermediate differentiation: case report

Pediatric midline tumors are devastating high-grade lesions with a dismal prognosis and no curative surgical options. Here, the authors report the clinical presentation, surgical management, whole-exome sequencing (WES), and clonality analysis of a patient with a radically resected H3K27M-mutant pineal parenchymal tumor (PPT) and spine metastases consistent with PPT of intermediate differentiation (PPTID). They identified somatic mutations in H3F3A (H3K27M), FGFR1, and NF1 both in the original PPT and in the PPTID metastases. They also found 12q amplification containing CDK4/MDM2 and chromosome 17 loss of heterozygosity overlapping with NF1 that resulted in biallelic NF1 loss. They noted a hypermutated phenotype with increased C>T transitions within the PPTID metastases and 2p amplification overlapping with the MYCN locus. Clonality analysis detected three founder clones maintained during progression and metastasis. Tumor clones present within the PPTID metastases but not the pineal midline tumor harbored mutations in APC and TIMP2.While the majority of H3K27M mutations are found in pediatric midline gliomas, it is increasingly recognized that this mutation is present in a wider range of lesions with a varied morphological appearance. The present case appears to be the first description of H3K27M mutation in PPTID. Somatic mutations in H3F3A, FGFR1, and NF1 have been suggested to be driver mutations in pediatric midline gliomas. Their clonality and presence in over 80% of tumor cells in our patient's PPTID are consistent with similarly crucial roles in early tumorigenesis, with progression mediated by copy number variations and chromosomal aberrations involving known oncogenes and tumor suppressors. The roles of APC and TIMP2 mutations in progression and metastasis remain to be investigated.

Neuroradiology of Brain Stem and Cervicomedullary tumours

Brain stem and cervicomedullary tumours are typical of paediatric age, 80% of them occurring in patients under 18 years of age, and comprising 10–15% of all childhood and adolescent brain tumours, as well as 20–25% of infratentorial locations.

They are characteristically pontine tumours (60% of the cases), but they commonly extend to involve the medulla, midbrain and cerebellum. Although most brain stem tumours are low grade gliomas, their prognosis is extremely severe (no more than 20% of patients are alive 3 years after diagnosis and the 5-year survival rate is 5%) because both the typical infiltrating nature and the neuro-anatomical location usually make them surgically unresectable. Surgery is generally limited to biopsy, partial decompression, or excission of the exophytic components, because of the extremely severe functional sequelae of even minor resections. Thus, the mainstay of therapy has been based on irradiation alone or combined with chemotherapy, doses of 5000–5500 cGy being usually adequate for tumour shrinkage or remission, even if recurrence is common after 10–15 months.

At present, it is very important to establish reliable, homogeneous, objective, and reproducible diagnostic criteria for the identification of patient subsets with predictable histology, prognosis and possible therapeutic management, in some cases histology, site and relationship of tumour enabling total or subtotal resection with a lower operative risk. Since its introduction, magnetic resonance imaging (MRI) has appeared the procedure of choice for the neuroradiologic study of the brain stem and brain stem tumours, enabling a more precise definition of their margins, a correct assessment of intrinsic and exophytic components, as well as a satisfactory characterization of pathologic tissue. MRI studies should include good quality T1-, PD- and T2-weighted images and T1-weighted images after gadolinium i.v., T2-weighted sagittal images being required for complete evaluation of tumour extent. Computed tomography is still superior in the identification of calcifications and acute intratumoral haemorrhage; it is rapidly performed, thus representing the first choice procedure in emergency, i.e. the diagnosis of hydrocephalus. Epstein has proposed the most widely accepted classification system of brain stem tumours, essentially based on neuroradiological findings, surgical and stereotactic biopsy and histology generally resulting in understaging. This classification system separates intrinsic (diffuse, focal, cervico-medullary), exophytic (anterolateral into cerebellopontine angle, posterolateral into brachium pontis, posterior into fourth ventricle) and cerebrospinal fluid seeding (positive cytology or myelography) tumors.

More recently, Barkovich – based on a multicentric study of some of the most important paediatric neurosurgery and neuro-oncology centres of the United States – has clearly defined the neuroradiological parameters which must be considered for an objective and reproducible assessment of brain stem gliomas, in order to identify patient subsets characterized by predictable histology, prognosis and possible therapeutic management. We agree with him, emphasizing that the evaluation of brain stem tumours must include a careful interpretation of all MRI findings (tumour site and origin; dimensions/degree of brain stem enlargement; tumour caudo-cranial and transverse extension; exophytic components; tumour characteristics as defined by MRI signal intensity; cysts, haemorrhage, necrosis, calcifications; ventricular dimensions and hydrocephalus; leptomeninengeal seeding) that can help in the definition of the following tumour subsets: diffuse pontine tumours, medullary tumours, cervicomedullary tumours, focal brain stem tumours.

With regard to the neuroradiological follow-up, in patients undergoing surgery (for biopsy decompression or less frequently for radicality), the role of the neuroradiologist is similar to that in other fields of neurosurgery, and concerns the quantitation of the extent of the resection and the identification of possible parenchymal injuries or postoperative haemorrhage, always keeping in mind the negative effects of postoperative reactive phenomena and the blood-brain disruption 24–48 hours to 30–40 days after surgery. However, the major contribution of the neuroradiologist is the objective evaluation of irradiation effects and recently of combined irradiation and chemotherapy. In our experience, the efficacy of irradiation is well evaluated by MRI only 3 or 6 months after the end of treatment, even if a clinical improvement is possible after 30–60 days. However, tumour shrinkage is rarely drastic, and its disappearance, as well as that of signal alterations, is exceptional. Qualitative modifications occurring within the tumour are more difficult to interpret, because of the appearance of cystic or pseudocystic areas, markedly increased enhancement, and small areas of haemorrhage may be related both to irradiation-induced regressive modifications and disease progression.

In conclusion, MRI represents the gold standard in the evaluation of brain stem and cervicomedullary tumors, always enabling a precise definition of tumour site and extent, and in most cases the diagnosis of nature, thus allowing the identification of patients who can undergo radical microsurgery. MRI follow-up controls the extent of resection and the effect of combined irradiation and chemotherapy; disease progression is evidenced and spinal seeding can be diagnosed.

However, the differentiation between tumour recurrence and irradiation-induced injury may be difficult if only based on morphological data. These limitations of MRI will probably be reduced by the advances in ultra-fast MRI technology and 18F-fluoro-deoxy-glucose positron emission tomography which supplies in vivo metabolic and functional information.

Surgical Application of the Suboccipital Subtonsillar Approach to Reach the Inferior Half of Medulla Oblongata Tumors in Adult Patients

Medulla oblongata (MO) tumors are uncommon in adults. Controversies about their treatment arise regarding the need for histological diagnosis in this eloquent area of the brain, weighing benefits of a reliable diagnosis, and the potential disadvantages of invasive procedures. As a broader variety of pathological findings could be found in this localization, the accurate histopathological definition could not only allow an adequate therapy but also can prevent the disastrous consequences of empiric treatments. There are few publications about their surgical management and all belongs to small retrospective cohorts. In this scenario, we are reporting two patients with exophytic or focal lesions in the inferior half of the medulla, who underwent surgery by suboccipital midline subtonsillar approach. This approach was not specifically described to reach MO before, and we found that the lesions produced a mild elevation of the tonsils providing a wide surgical view from the medulla to the foramen of Luchska laterally, and up to the middle cerebellar peduncle, offering a wide and safe access.

Prognostic factors in adult brainstem gliomas: a multicenter, retrospective analysis of 101 cases

BACKGROUND

Adult brainstem gliomas (BSG) are uncommon and poorly understood with respect to prognostic factors. We retrospectively evaluated the clinical, radiographic, histologic, and treatment features from 101 adults with presumed or biopsy proven BSG to determine prognostic factors.

PATIENTS AND METHODS

We reviewed the records of patients diagnosed from 1987-2005. We used Cox proportional hazard models to determine prognostic factors.

RESULTS

These 50 male and 51 female patients ranged in age from 18 to 79 years at diagnosis (median 36 years) with follow-ups from 1 to 261 months (median 47 months). The overall survival for all patients at 5 and 10 years was 58% and 41%, respectively, with a median survival of 85 months (range 1-228). Out of 24 candidate prognosis factors, we selected seven covariates for proportional hazards model by Lasso procedure: age of diagnosis, ethnicity, need for corticosteroids, tumor grade, dysphagia, tumor location, and karnofsky performance status (KPS). Univariate analysis showed that these seven factors are significantly associated with survival. Multivariate analysis showed that four covariates significantly increased hazard for survival: ethnicity, tumor location, age of diagnosis, and tumor grade.

CONCLUSIONS

In this study, we identified four prognostic factors that were significantly associated with survival in adults with BSGs. Overall, these patients have a better prognosis than children with BSGs reported in the literature. These results call for larger prospective studies to fully assess the importance of these factors in the clinical setting and to help stratify patients in future clinical studies.

Advances toward an understanding of brainstem gliomas

The diagnosis of brainstem glioma was long considered a single entity. However, since the advent of magnetic resonance imaging in the late 1980s, neoplasms within this anatomic region are now recognized to include several tumors of varying behavior and natural history. More recent reports of brainstem tumors include diverse sites such as the cervicomedullary junction, pons, midbrain, or the tectum. Today, these tumors are broadly categorized as either diffuse intrinsic gliomas, most often in the pons, or the nondiffuse brainstem tumors originating at the tectum, focally in the midbrain, dorsal and exophytic to the brainstem, or within the cervicomedullary junction. Although we briefly discuss the nondiffuse tumors, we focus specifically on those diffuse brainstem tumors that regrettably still carry a bleak prognosis.

Treatment of childhood diffuse brain stem tumors: comparison of results in different treatment modalities

BACKGROUND

Diffuse brainstem tumors in children are rare and its treatment is controversial. Although radiotherapy (RT) used to be the treatment of choice, results remained unsatisfactory. The association of RT with other therapies is common, but lacks scientific data regarding its efficacy. Comparison of results of irradiation alone versus combined treatment modalities is crucial in improving survival.

METHOD

The authors reviewed twenty-four patients with diffuse brainstem tumors, with mean age of 7 years, treated from December 90 to November 99, at the University of Sao Paulo, Brazil. These patients were subdivided in four groups according to the treatment option at the onset of symptoms. Four patients were treated with radiation alone (total dose of 50 Gy to 62.4 Gy), 6 patients with chemotherapy and radiation, 8 with tamoxifen and radiation and 6 with tamoxifen, radiation and chemotherapy. The results of the different groups were them compared.

FINDINGS

Clinical response was observed in 83.3% of our children, briefly followed by progressive disease. Mean survival was 17 months with no statistically significant differences among the groups. Four patients were alive at the end of the study, with a mean survival of 32.4 months, all of them received combined therapy, but with no statistically significant differences.

CONCLUSIONS

Neither the association of radiation therapy with chemotherapy, tamoxifen nor both have showed survival improvement. The prognosis of these patients remains very poor and only investigational trials would justify a highly aggressive approach.

Fractionated stereotactic conformal radiation therapy of brain stem gliomas: outcome and prognostic factors

BACKGROUND AND PURPOSE

Evaluation of outcome and prognostic factors in patients with brain stem glioma (BSG) following fractionated stereotactic radiotherapy (FSRT).

MATERIALS AND METHODS

Between 1990 and 1997, we treated 41 patients with FSRT in a phase I/II trial. Median age was 24 years. Out of 36 patients with histologically proven glioma, ten had a partial tumour resection. Histology revealed low grade gliomas in 30 patients and anaplastic gliomas in six patients. A mean total dose of 54 Gy was given in daily fractions of 1.8 Gy. Median follow-up was 12 months.

RESULTS

Three patients died during FSRT. Neurological improvement was achieved in 19/38 patients. Reduction of tumour size was reported in 12/38, in 16 patients the lesion was unchanged, ten showed progression. Median time to progression was 23 months, median overall survival 40 months with an actuarial survival of 83% at 1 year, 55% at 3 years and 33% at 5 years. In 20 of 22 patients with recurrence progression was inside the target volume. Significant prognostic factors for survival were clinical and radiological response 6 weeks after FSRT. Treatment toxicity was mild. Ototoxicity occurred in one patient.

CONCLUSIONS

FSRT is a feasible treatment modality for BSG with tolerable toxicity. The risk of marginal failure is low.

Adult brainstem gliomas

OBJECTIVE

To evaluate prognostic factors and survival of adult patients with brainstem gliomas.

BACKGROUND

Brainstem glioma is a disease found primarily in children, with a median survival of only 9 to 12 months. However, the prognosis and survival of adults with this disease has not been determined with precision.

METHODS

We conducted a retrospective analysis of patients older than 16 years at Memorial Sloan-Kettering Cancer Center with histologically proved or presumed brainstem glioma diagnosed between 1989 and 1997. We assessed the effect of gender, age at diagnosis, cranial nerve involvement, duration of symptoms, exophytic component, MRI enhancement, site of disease, treatment, and Karnofsky performance status on survival.

RESULTS

Twenty-three patients were identified, but complete information was available in only 19 (12 males and 7 females). Patients ranged in age from 17 to 70 years (median, 40 years). Twelve patients were treated with radiotherapy at diagnosis and seven were observed, three of whom received subsequent radiotherapy. Median survival is 54 months (range, 3 to 98 months) and the 5-year survival is 45%. There was a trend for patients with a higher performance status at diagnosis to have longer survival, but this did not reach statistical significance. Other factors did not affect survival.

CONCLUSION

Adults with brainstem gliomas may survive significantly longer than children, suggesting the disease may be less aggressive in adults. Furthermore, some patients with a long duration of symptoms or tectal or cervicomedullary tumors may be managed initially with observation alone.

Prognostic factors and therapeutic options of radiotherapy in pediatric brain stem gliomas

BACKGROUND

A retrospective analysis was made to clarify the relationship between prognosis, radiation dose and survival of brain stem gliomas.

METHODS

From 1983 to 1995, 22 children with brain stem tumors were treated by radiotherapy in the Veterans General Hospital-Taipei. Twelve patients had pathology proof and the remainder were diagnosed by computerized tomography and/or magnetic resonance imaging. Seven patients had postoperative radiotherapy. Fifteen patients had radiotherapy as primary management, five of whom had adjuvant chemotherapy. All patients received 4000-7060 cGy, either in conventional daily or hyperfractionated twice daily radiotherapy. Survival from date of diagnosis was calculated by the Kaplan-Meier method. Univariate analyses and multivariate analyses were calculated by the log rank test and the Cox proportional hazard model, respectively.

RESULTS

Most patients showed improvement following treatment. The overall 2-year survival rate was 55.5% with a median survival of 27.1 months. Two-year survival for patients with primary management of operation and radiotherapy (n = 7), radiotherapy alone (n = 10) and radiotherapy with adjuvant chemotherapy (n = 5) were 66.7, 50 and 53.3%, respectively. In univariate analysis, the study revealed that the growth pattern of tumors and the simultaneous presence of cranial neuropathy and long tract sign were significant prognostic factors (P = 0.017 and 0.036). A trend of better outcome with radiation dose > 6600 cGy and the hyperfractionation scheme was also noted in our study (P = 0.0573 and 0.0615). However, only the hyperfractionation scheme was also noted in our study (P = 0.0573 and 0.0615). However, only the hyperfractionation scheme showed significance in multivariate analyses (P = 0.0355). Survival was not significantly affected by age, gender or method of diagnosis.

CONCLUSION

Radiotherapy appears to be an effective treatment modality of brain stem tumors. Patients with both cranial neuropathy and long tract signs had a poorer outcome. Hyperfractionated radiotherapy may give better local control and lead to better survival.