Incidence and patterns of neuraxis metastases in children with diffuse pontine glioma

Clinical applications of PET and PET/CT in pediatric malignancies

The common childhood cancers are leukemia, CNS tumors, lymphomas, soft-tissue tumors (such as rhabdomyosarcoma and fibrosarcoma), neuroblastoma, malignant bone tumors, germ cell tumors with neoplasms of gonads and hepatic tumors. Usually the conventional imaging modalities, such as x-ray, ultrasound, computed tomography (CT) and MRI, are being routinely used for the management of these pediatric malignancies. However, most of these modalities provide structural information and are lacking in functional/metabolic status of these malignancies. Recently, PET and PET/CT have emerged as a functional diagnostic imaging modality for the management of various cancers in adult population. Up to now most of the data published in the literature are on PET alone. PET used in conjunction with CT is useful as it provides an enhanced view of the anatomical details and the malignant focus then can be located with highest accuracy. PET and PET/CT has been found to be useful in, for example, CNS tumors, lymphomas, soft-tissue tumors, neuroblastoma, malignant bone tumors and germ cell tumors. PET/CT has a limited role in early diagnosis, however, it plays an important role in initial staging, treatment response evaluation and detection of metastatic disease in these cancers. Despite the fact that PET/CT has better diagnostic value when compared with conventional imaging, such as CT and MRI, in the management of many pediatric cancers, there are certain limitations. PET/CT has a limited role in detection of lesions smaller than 5 mm, well-differentiated tumors and tumors with low metabolic rate. Many infections and inflammation can lead to false-positive PET/CT results. In the present review we will discuss the various clinical indications of PET and PET/CT in pediatric cancers.

Prospective neuraxis MRI surveillance reveals a high risk of leptomeningeal dissemination in diffuse intrinsic pontine glioma

Prognosis of diffuse intrinsic pontine gliomas (DIPGs) remains poor. Failure has been predominantly local, with leptomeningeal dissemination (LD) occurring in 4-33% of patients in pre-MRI era series. Routine craniospinal imaging after initial treatment may reveal other relapse patterns relapse. Sixteen consecutive pediatric patients with DIPG treated between 2006 and 2009 were retrospectively reviewed. Treatment regimens, recurrence patterns, survival, and pathologic diagnosis were recorded. Fourteen patients received involved-field radiotherapy to 54 Gy, and two patients received craniospinal irradiation for LD at presentation. Neuraxis MRI was performed at diagnosis and at 4 month intervals following radiotherapy. Fifteen patients have had progression of disease (median progression-free survival 5.0 ± 1.2 months), and 13 patients have died (median survival 9.0 ± 1.4 months). Local failure occurred in 12 patients (75%). LD occurred in nine patients (56%). LD was present at diagnosis in three patients, after initial staging and treatment in six patients, and during autopsy in two patients. Median overall survival was 12.0 ± 3.3 months without LD and 8.0 ± 2.1 months with LD (P = 0.059, log rank test). Median progression-free survival was 9.5 ± 3.9 months without LD and 3.0 ± 2.1 months with LD (P = 0.012, log rank test). The high incidence of LD probably reflects liberal use of spine MRI surveillance. All patients should undergo routine craniospinal imaging at diagnosis and follow-up. Central nervous system prophylaxis should be considered in future clinical trials.

A phase I trial of temozolomide and lomustine in newly diagnosed high-grade gliomas of childhood

A phase I trial was conducted to determine the maximum tolerated dose (MTD) of temozolomide given in combination with lomustine in newly diagnosed pediatric patients with high-grade gliomas. Response was assessed following two courses of therapy at the MTD. Temozolomide was administered to cohorts of patients at doses of 100, 125, 160, or 200 mg/m(2) on days 1-5, along with 90 mg/m(2) lomustine on day 1. Two courses of lomustine/temozolomide were given prior to radiation therapy (RT) and up to six courses were administered afterward. Thirty-two patients were enrolled. Dose-limiting myelosuppression was seen in two of three patients enrolled at the 200 mg/m(2) dose level. One of 14 patients in the expanded MTD cohort (160 mg/m(2)) experienced dose-limiting thrombocytopenia. After two courses at the MTD, one patient with a 5-mm enhancing nodule postoperatively had a complete response, one patient with a large residual temporal lobe glioblastoma had a partial response, and eight patients had stable disease. Several patients developed transient radiographic worsening after completing RT. Median 1- and 2-year overall survivals at the MTD were 60% +/- 13% and 40% +/- 13% with a median of 17.6 months. Thirteen of 20 patients (65%) who underwent MRI scans within 6 months prior to death developed metastatic disease. In conclusion, when administered with 90 mg/m(2) lomustine on day 1, the MTD of temozolomide is 160 mg/m(2)/day x 5. Radiographic changes following RT make determination of early tumor progression difficult. Metastatic disease is common prior to death.

Unusual case of leptomeningeal dissemination of a diffuse pontine high-grade astrocytoma in a child

A 12-year-old girl was seen in our hospital and diagnosed with diffuse pontine glioma. Treatment with radiotherapy was suggested, but the parents rejected this plan and took the child to another hospital where partial resection of the tumor was performed. The histological diagnosis was anaplastic astrocytoma. Returning to our hospital, the parents agreed to radiotherapy which was given in a total dose of 54 Gy. However, 3 months after completion of radiotherapy, the child developed widespread leptomeningeal dissemination of her disease and died 12 months after the initial diagnosis. Since no effective curative methods of treatment exist for patients with diffuse pontine gliomas and surgical intervention is obsolete in this situation and may facilitate leptomeningeal dissemination of the disease, further innovative methods of treatment are needed to improve the bleak prognosis of these patients.

Conventional MRI cannot predict survival in childhood diffuse intrinsic pontine glioma

Diffuse intrinsic pontine glioma (DIPG) of childhood has a dismal prognosis. Clinical trials of new agents are vital and it is essential that the correct endpoints and disease assessments are chosen. A retrospective review of magnetic resonance imaging (MRI) scanning in a pure population of DIPG was undertaken. Baseline diagnostic MRI findings included; local tumour extension in upper medulla (74%) or midbrain (62%), metastatic disease (3%), basilar artery encasement (82%), necrosis (33%), intratumoural haemorrhage (26%), hydrocephalus (23%) and dorsal exophytic component (18%). Post-treatment MRI scans demonstrated increases in; leptomeningeal metastatic disease (16%), cystic change/necrosis (48%), enhancement (72%) and intratumoural haemorrhage (32%). Response rates were calculated according to both RECIST (4%) and WHO (24%) criteria. No MRI parameter in either the diagnostic or response scans had prognostic significance. We recommend that currently primary endpoints for DIPG clinical trials should be overall or possibly progression free survival and that new advanced functional imaging techniques should be explored as possible surrogate markers for novel therapy activity rather than conventional MRI response criteria.

Pattern of recurrence in paediatric malignant glioma: an institutional experience

BACKGROUND

The purpose of this retrospective study was to investigate the pattern of recurrence in paediatric malignant gliomas.

MATERIAL AND METHODS

We reviewed the notes, diagnostic imaging and treatment charts of 30 consecutive paediatric patients (age less than 18 years at diagnosis, range 0.5-17 years) presenting with a malignant glioma presenting to the paediatric oncology unit at the Royal Marsden Hospital over a 10-year period. The imaging at the time of first relapse was compared with the initial diagnostic scans to define a relapse as local, marginal or distant.

RESULTS

Median follow-up was 13 months (range 1-99 months). Twenty-four of 30 patients (80%) showed evidence of progression with a median time to progression of 8.5 months (range 3-64 months). Thirteen out of 24 patients developed local or marginal recurrences while 11/24 patients recurred at distant sites as site of first relapse (46%).

CONCLUSION

Our series suggests that the pattern of relapses in paediatric malignant gliomas could be different from that reported in adult studies as we observed a significant incidence of distant relapses. Larger prospective series need to be conducted to investigate the clinico-biological characteristics of the population at high risk for leptomeningeal dissemination.