A review of astrocytoma in childhood

Genetic and epigenetic contribution to astrocytic gliomas pathogenesis

Astrocytic gliomas are the most common and lethal form of intracranial tumors. These tumors are characterized by a significant heterogeneity in terms of cytopathological, transcriptional, and (epi)genomic features. This heterogeneity has made these cancers one of the most challenging types of cancers to study and treat. To uncover these complexities and to have better understanding of the disease initiation and progression, identification, and characterization of underlying cellular and molecular pathways related to (epi)genetics of astrocytic gliomas is crucial. Here, we discuss and summarize molecular and (epi)genetic mechanisms that provide clues as to the pathogenesis of astrocytic gliomas.

Neurosurgical treatment of low-grade cerebellar astrocytoma in children and adolescents: a single consecutive institutional series of 100 patients

OBJECT

The objective of this study was to delineate the long-term results of surgical treatment of pediatric low-grade cerebellar astrocytoma.

METHODS

One hundred consecutive children and adolescents (0-19 years old) who underwent primary tumor resection for a low-grade cerebellar astrocytoma during the years 1980-2011 were included in this retrospective study on surgical morbidity, mortality rate, academic achievement, and/or work participation. Gross motor function and activities of daily living were scored according to the Barthel Index.

RESULTS

Of the 100 patients, 61 children were in the 1st decade, and 39 were 10-19 years old. The male/female ratio was 1.13:1 (53 males, 47 females). No patients were lost to follow-up. There were no deaths in this series and all 100 patients are currently alive. In 29 patients, the follow-up duration was less than 10 years, in 37 it was between 10 and 19 years, and in 34 it was between 20 and 31 years. The Barthel Index was 100 (normal) in 97 patients, 90 in 2 patients, and 40 in the last patient. A total of 113 tumor resections were performed. Two patients underwent further tumor resection due to MRI-confirmed residual tumor demonstrated on the immediate postoperative MR image (obtained the day after the initial procedure). Furthermore, 9 children underwent repeat tumor resection after MRI-confirmed progressive tumor recurrence up to 10 years after the initial operation. Two of these patients also underwent a third resection, without subsequent radiation therapy, and have experienced 8 and 12 years of tumor-free follow-up thereafter, respectively. A total of 15% of the patients required treatment for persistent hydrocephalus.

CONCLUSIONS

Low-grade cerebellar astrocytoma is a surgical disease, in need of long-term follow-up, but with excellent long-term results. Nine percent of the children in this study underwent repeated surgery due to progressive tumor recurrence, and 15% were treated for persistent hydrocephalus.

Imaging tumors of the pediatric central nervous system

Primary tumors of the central nervous system (CNS) are the second most common neoplasms in children and the leading cause of death in this patient population. The primary objective of this article is to describe the most common pediatric brain tumors and to offer an overview of their respective imaging features, primarily on magnetic resonance imaging. Precise anatomic characterization is essential for developing an appropriate differential diagnosis. Once equipped with this critical information, physicians should be better able to make firm diagnoses, leading to improved disease management and patient outcomes in the setting of CNS tumors of childhood.

The regulation of cell migration by PTEN

In vertebrates, the tumour suppressor PTEN (phosphatase and tensin homologue deleted on chromosome 10) regulates many cellular processes through its PtdIns(3,4,5)P3 lipid phosphatase activity, antagonizing PI3K (phosphoinositide 3-kinase) signalling. Given the important role of PI3Ks in the regulation of directed cell migration and the role of PTEN as an inhibitor of migration, it is somewhat surprising that data now indicate that PTEN is able to regulate cell migration independent of its lipid phosphatase activity. Here, we discuss the role of PTEN in the regulation of cell migration.

Survival rates in patients with primary malignant brain tumors stratified by patient age and tumor histological type: an analysis based on Surveillance, Epidemiology, and End Results (SEER) data, 1973-1991

OBJECT

The authors present population-based survival rate estimates for patients with malignant primary brain tumors based on an analysis of 18 years of data obtained from the Surveillance, Epidemiology, and End Results (SEER) program of the National Cancer Institute.

METHODS

Estimates of survival rates at 2 and 5 years after diagnosis for patients with specific histological tumor types were categorized by patient's age at diagnosis (< or = 20 years, 21-64 years, and 65 years or older) and by the time period in which the patients were diagnosed (1973-1980, 1981-1985, 1986-1991). Where appropriate, survival estimates were adjusted for changing patterns in the mean age at diagnosis.

CONCLUSIONS

The authors observed a pattern of declining survival rates in patients with increasing age of the patient at diagnosis for most histological groups and overall improvements in survival rates of patients across these time periods adjusting for age at diagnosis. There were improvements in 2- and 5-year survival rates over the three time periods for children and adults with medulloblastoma and for adults with astrocytoma and oligodendroglioma. Improvements in survival rates for pediatric patients with medulloblastoma have leveled off in the most recent time period, and gender differences in survival rates for patients with this tumor, which were present in the 1970s, have disappeared. Clinically significant improvements in survival rates were not apparent in patients aged 65 years and older. Changes in diagnostic and treatment procedures since the mid-1970s have resulted in improved survival rates for patients diagnosed as having medulloblastoma, oligodendroglioma, and astrocytoma, controlling for age at diagnosis. Glioblastoma multiforme continues to be the most intractable brain tumor.

Cerebellar astrocytoma: experience with 54 cases surgically treated at the Mayo Clinic, Rochester, Minnesota, from 1978 to 1990

A comprehensive review of the literature has shown that the treatment of choice for cerebellar astrocytomas has primarily been gross-total resection of the mass and gross-total resection of the enhancing portion of pilocytic astrocytomas. Most large scale studies of postresection survival rates of patients with cerebellar astrocytomas were conducted when computerized tomography (CT) and magnetic resonance (MR) imaging were not readily available. It has been shown that postoperative CT scans or MR images are more reliable than the surgeon's estimate of the degree of tumor resection at the time of surgery. It is not possible, therefore, to make an accurate determination regarding a postresection prognosis based on the degree of suspected tumor resection without the availability of appropriate radiographic imaging. In this study, the authors retrospectively evaluated the treatment of 54 patients with cerebellar astrocytoma who underwent surgery at the Mayo Clinic in Rochester, Minnesota, from 1978 through 1990. Preoperative and postoperative CT scans or MR images were available in all 54 patients.

Somatic mutations in the neurofibromatosis 1 gene in human tumors

The neurofibromatosis 1 (NF1) gene product, neurofibromin, contains a GTPase-activating protein (GAP)-related domain, or NF1 GRD, that is able to down-regulate p21ras by stimulating its intrinsic GTPase. Since p21ras.GTP is a major regulator of growth and differentiation, mutant neurofibromins resulting from somatic mutations in the NF1 gene might interfere with ras signaling pathways and contribute to the development of tumors. We describe an amino acid substitution in the NF1 GRD, altering Lys-1423, that has occurred in three tumor types: colon adenocarcinoma, myelodysplastic syndrome, and anaplastic astrocytoma, and in one family with neurofibromatosis 1. The GAP activity of the mutant NF1 GRD is 200- to 400-fold lower than that of wild type, whereas binding affinity is unaffected. Thus, germline mutations in NF1 that cause neurofibromatosis 1 can also occur in somatic cells and contribute to the development of sporadic tumors, including tumors not associated with neurofibromatosis 1.