Paul G. Fisher

Pediatric astrocytomas with monomorphous pilomyxoid features and a less favorable outcome

Among tumors classified as pilocytic astrocytoma (PA) in the Johns Hopkins Hospital Department of Pathology files, we identified 18 cases with a distinctive monomorphous pilomyxoid histological pattern and a higher recurrence rate than that of PA with classical histological features (classical PA). The majority of the tumors occurred in infants and young children and involved the hypothalamic/chiasmatic region. The tumors were histologically similar to PA, but they were more monomorphous and more myxoid. Rosenthal fibers were not seen and only 1 of 18 tumors had eosinophilic granular bodies. At the end of the follow-up period, 6 patients were dead and 12 were alive with evidence of disease. Progression free survival (PFS) at 1 year was 38.7%. In comparison, we identified a control group of 13 classical PAs in the same age range and location as the study group. In this group, PFS at 1 year was 69.2%, which was significantly better than that for pilomyxoid tumors (p = 0.04). There was no CSF dissemination or death due to tumor progression among patients with classical PA. Eight of these patients are alive with recurrent disease, and 4 have no evidence of disease. While the monomorphous pilomyxoid tumors have some resemblance to classical PA, our results suggest that the former is a more aggressive variant or a separate entity that needs to be recognized for prognostic purposes.

Oncogenic BRAF mutation with CDKN2A inactivation is characteristic of a subset of pediatric malignant astrocytomas.

Malignant astrocytomas are a deadly solid tumor in children. Limited understanding of their underlying genetic basis has contributed to modest progress in developing more effective therapies. In an effort to identify such alterations, we performed a genome-wide search for DNA copy number aberrations (CNA) in a panel of 33 tumors encompassing grade 1 through grade 4 tumors. Genomic amplifications of 10-fold or greater were restricted to grade 3 and 4 astrocytomas and included the MDM4 (1q32), PDGFRA (4q12), MET (7q21), CMYC (8q24), PVT1 (8q24), WNT5B (12p13), and IGF1R (15q26) genes. Homozygous deletions of CDKN2A (9p21), PTEN (10q26), and TP53 (17p3.1) were evident among grade 2 to 4 tumors. BRAF gene rearrangements that were indicated in three tumors prompted the discovery of KIAA1549-BRAF fusion transcripts expressed in 10 of 10 grade 1 astrocytomas and in none of the grade 2 to 4 tumors. In contrast, an oncogenic missense BRAF mutation (BRAF(V600E)) was detected in 7 of 31 grade 2 to 4 tumors but in none of the grade 1 tumors. BRAF(V600E) mutation seems to define a subset of malignant astrocytomas in children, in which there is frequent concomitant homozygous deletion of CDKN2A (five of seven cases). Taken together, these findings highlight BRAF as a frequent mutation target in pediatric astrocytomas, with distinct types of BRAF alteration occurring in grade 1 versus grade 2 to 4 tumors.

Impaired human hippocampal neurogenesis after treatment for central nervous system malignancies

The effects of cancer treatments such as cranial radiation and chemotherapy on human hippocampal neurogenesis remain unknown. In this study, we examine neuropathological markers of neurogenesis and inflammation in the human hippocampus after treatment for acute myelogenous leukemia or medulloblastoma. We demonstrate a persistent radiation‐induced microglial inflammation that is accompanied by nearly complete inhibition of neurogenesis after cancer treatment. These findings are consistent with preclinical animal studies and suggest potential therapeutic strategies. Ann Neurol 2007

Profile of Daily Life in Children With Brain Tumors: An Assessment of Health-Related Quality of Life

PURPOSE The survival of children with CNS tumors approaches 70%, yet health-related quality of life (HRQOL) has not been investigated rigorously in this population. We aimed to show that universal assessment of HRQOL could be obtained easily by using the PedsQL 4.0 and to provide a composite profile of their daily lives. PATIENTS AND METHODS The PedsQL was administered to all patients seen in the neuro-oncology clinic at Lucile Packard Childrens Hospital (Palo Alto, CA) from December 2001, to September 2002. Patients were compared with healthy controls by using two-sided t tests to evaluate statistically significant differences. RESULTS One hundred thirty-four patients (73 male; mean age +/- standard deviation, 11.8 +/- 5.4 years; 55 had low-grade glioma, 32 had medulloblastoma/primitive neuroectodermal tumor/embryonal tumor, 17 had malignant astrocytoma, nine had germ-cell tumor, and 21 had other types of tumors) were assessed, each in less than 20 minutes. Scores on both child and parent-proxy reports for the total HRQOL, psychosocial, physical, emotional, social, and school-functioning scales were all significantly lower than controls (P < .01). Patients with low-grade glioma were reported to have the highest total HRQOL. Children receiving radiation therapy (XRT) but no chemotherapy had significantly lower total, psychosocial, emotional, and social functioning than those receiving other treatments, including XRT plus chemotherapy. CONCLUSION The PedsQL can be used to assess HRQOL rapidly and easily in children with CNS tumors, who have significantly worse HRQOL than healthy children. Children receiving XRT fare worse overall; chemotherapy added to XRT does not seem to worsen HRQOL. Assessment of HRQOL should be included as an outcome in future clinical trials.

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.

A clinicopathologic reappraisal of brain stem tumor classification: Identification of pilocytic astrocytoma and fibrillary astrocytoma as distinct entities

Brain stem tumors in children have been classified pathologically as low grade or high grade gliomas and descriptively as diffuse gliomas, intrinsic gliomas, midbrain tumors, tectal gliomas, pencil gliomas, dorsal exophytic brain stem tumors, pontine gliomas, focal medullary tumors, cervicomedullary tumors, focal gliomas, or cystic gliomas.

Outcome analysis of childhood low-grade astrocytomas.

We aimed to determine the long‐term natural history of low‐grade astrocytomas (LGA) in children, with respect to pathology, and to evaluate influence of treatment on survival.

Hedgehog-responsive candidate cell of origin for diffuse intrinsic pontine glioma

Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive tumors of childhood that are almost universally fatal. Our understanding of this devastating cancer is limited by a dearth of available tissue for study and by the lack of a faithful animal model. Intriguingly, DIPGs are restricted to the ventral pons and occur during a narrow window of middle childhood, suggesting dysregulation of a postnatal neurodevelopmental process. Here, we report the identification of a previously undescribed population of immunophenotypic neural precursor cells in the human and murine brainstem whose temporal and spatial distributions correlate closely with the incidence of DIPG and highlight a candidate cell of origin. Using early postmortem DIPG tumor tissue, we have established in vitro and xenograft models and find that the Hedgehog (Hh) signaling pathway implicated in many developmental and oncogenic processes is active in DIPG tumor cells. Modulation of Hh pathway activity has functional consequences for DIPG self-renewal capacity in neurosphere culture. The Hh pathway also appears to be active in normal ventral pontine precursor-like cells of the mouse, and unregulated pathway activity results in hypertrophy of the ventral pons. Together, these findings provide a foundation for understanding the cellular and molecular origins of DIPG, and suggest that the Hh pathway represents a potential therapeutic target in this devastating pediatric tumor.

Incidence patterns for ependymoma: a Surveillance, Epidemiology, and End Results study

OBJECT Previous small studies disagree about which clinical risk factors influence ependymoma incidence. The authors analyzed a large, population-based cancer registry to examine the relationship of incidence to patient age, sex, race, and tumor location, and to determine incidence trends over the past 3 decades. METHODS Data were obtained from the Surveillance, Epidemiology, and End Results (SEER-9) study, which was conducted from 1973 to 2003. Histological codes were used to define ependymomas. Age-adjusted incidence rates were compared by confidence intervals in the SEER*Stat 6.2 program. Multiplicative Poisson regression and Joinpoint analysis were used to determine annual percentage change and to look for sharp changes in incidence, respectively. RESULTS From the SEER database, 1402 patients were identified. The incidence rate per 100,000 person-years was significantly higher in male than in female patients (males 0.227 +/- 0.029, females 0.166 +/- 0.03). For children, the age at diagnosis differed significantly by tumor location, with the mean age for patients with infratentorial tumors calculated as 5 +/- 0.4 years; for supratentorial tumors it was 7.77 +/- 0.6 years, and for spinal lesions it was 12.16 +/- 0.8 years. (Values are expressed as the mean +/- standard error [SE].) Adults showed no difference in the mean age of incidence by location, although most tumors in this age group were spinal. Between 1973 and 2003, the incidence increased significantly among adults but not among children, and there were no sharp changes at any single year, both before and after age adjustment. CONCLUSIONS Males have a higher incidence of ependymoma than do females. A biological explanation remains elusive. Ependymoma occurs within the CNS at distinct locations at different ages, consistent with hypotheses postulating distinct populations of radial glial stem cells within the CNS. Ependymoma incidence appears to have increased over the past 3 decades, but only in adults.

RADIATION THERAPY FOR INTRACRANIAL GERM CELL TUMORS

PURPOSE To review the combined experiences of University of California, San Francisco, and Stanford University Medical Center in the treatment of intracranial germ cell tumors (GCT) and to assess the impact of craniospinal radiation (CSI) on patterns of relapse, progression-free survival (PFS), and overall survival (OS). PATIENTS AND METHODS Ninety-three patients received radiation for newly diagnosed intracranial GCTs, including 49 germinomas, 16 nongerminomatous GCTs (NGGCT), and 28 with no biopsy. Median follow-up for surviving patients was 4.5 years (range 0.25-34). Tests for variables correlating with OS and PFS were conducted using Cox proportional hazards model. RESULTS Five-year PFS and OS rates were 60% +/- 15% and 68% +/- 14% for patients with NGGCT and 88% +/- 5% and 93% +/- 4% for those with germinoma. Of 6 patients with localized NGGCT who did not receive CSI, 1 experienced an isolated spinal recurrence but was salvaged. Of 41 patients with localized germinoma, 6 who received CSI and 35 who did not, no isolated spinal cord relapses occurred. Twenty-one patients with localized germinoma received neither CSI nor whole brain radiation. Of these, none of 18 with ventricular radiation relapsed. One of 3 patients with primary tumor radiation relapsed intracranially but had only received 11 Gy at initial treatment. On multivariate analysis, germinoma histology but not CSI correlated with improved PFS and OS. CONCLUSION CSI is not indicated in the treatment of localized germinomas. For patients with localized germinomas treated with radiation alone, we recommend ventricular irradiation followed by primary tumor boost to a total of 45-50 Gy.