Medical and oncological management of pediatric brain tumors

Pharmacotherapy of malignant astrocytomas of children and adults: current strategies and future trends

This article reviews the conceptual progression in the pharmacological therapy of malignant astrocytoma (MA) over the past decade, and its future trends. It is a selective rather than an exhaustive inventory of literature citations. The experience of the Brain Tumour Cooperative Group (BTCG) and earlier phase III trials are summarised to place subsequent phase II and I studies of single and combination agent chemotherapy in perspective. The BTCG experience of the 1970s to 1980s may be summarised to indicate that external beam radiotherapy (EBRT) is therapeutic, although not curative, and not further improved upon by altering fractionation schedules, or the addition of radioenhancers. Whole brain and reduced whole brain EBRT with focal boost were comparable regimens. Nitrosourea-based, adjuvant chemotherapy provided a modest improvement in survival among adult patients, which was comparable with that of other single drugs or multidrug regimes. The multiagent schedules, however, had a correspondingly higher toxicity rate. Intra-arterial administration was associated with significant risk, which conferred no therapeutic advantage. The trend of the past decade has been towards multiagent chemotherapy although its benefit cannot be predicted from the classic prognostic factors. Published experience with investigational trials utilising myeloablative chemotherapy with autologous bone marrow or peripheral blood stem cell haemopoietic support, drug delivery enhancement methods and radiosensitisers is critically reviewed. None of these approaches have achieved wide-spread acceptance in the treatment of adult patients with MA. Greater attention is placed on recent 'chemoradiotherapy' trials, which attempt to integrate and maximise the cytoreductive potential of both modalities. This approach holds promise as an effective means to delay or overcome the evolution of tumour resistance, which is probably one of the dominant determinants of prognosis. However, the efficacy of this approach remains unproven. New chemotherapeutic agents as well as biological response modifiers, protein kinase inhibitors, angiogenesis inhibitors and gene therapy are also discussed; their role in the therapeutic armamentarium has not been defined.

Pediatric neuro-oncology: controversies in current therapy

Current Phase III clinical trials for the treatment of malignant central nervous system (CNS) tumors of childhood are reviewed. Combination neurosurgical, radiation treatment and chemotherapy have improved both the quality and duration of life for the affected children. Controversy exists regarding the appropriate adjunctive chemotherapy for newly diagnosed CNS neoplasms but this is being prospectively studied in controlled trials. Major dilemmas persist regarding the management of low-grade gliomas and recurrent CNS neoplasms. Preliminary data on possibly favourable protocols are cited. Future directions for clinical and basic laboratory investigation are also briefly reviewed.

Astrocytoma in childhood: survival and performance

Seventy-nine children (35 female, 44 male) with proven or presumed astrocytoma were treated from 1967 to 1987. The tumors were supratentorial located in 24 children, cerebellar in 21 children, and pontine in 34 children. If possible, a radical tumor resection (4%), a subtotal tumor resection (51%), or a biopsy (8%) was performed. The predominant pathological Kernohan grading for the supratentorial, cerebellar, and pontine located tumors were grades II, II, and IV respectively. Histology was unknown in 15 out of 34 pontine tumors and in 1 out of 24 supratentorial tumors. Low-graded tumors (46%) were irradiated with a local field (1.8/45-50 Gy) and children with high-graded tumors (34%) received a total brain irradiation (1.8/40 Gy) followed by a boost irradiation (10 Gy) in 5 or 6 fractions. Overall 1-, 5-, and 10-year survivals of children with supratentorial, cerebellar, and pontine located tumors were 96%-91%-46%, 95%-95%-95%, and 35%-20%-20% respectively. For all tumor locations, 77% of deaths occurred within 2 years of treatment. The performance status of both children with supratentorial and cerebellar astrocytoma showed an increase during the first year of treatment and then stabilized on a rather high level (mean performance after 5 years of 60% and 70% respectively). Children with pontine tumors showed a steep decrease in performance status during the first year of treatment and then stabilized on a low level (mean performance after 5 years of 15%). In our study, children with supratentorial astrocytoma showed improvement in both survival and performance status after irradiation following surgical removal of the tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of cis-dichlorodiamineplatinum on glioma cell morphology and cell cycle kinetics in tissue culture

C6 glioma cells (CCL 107) were cultured for three days and then treated with cis-dichlorodiamineplatinum (cis-DDP) at doses of 0.2-10 micrograms/ml medium. Changes in DNA synthesis and DNA content, as well as morphology of cells and chromatin distribution, were examined from the first post-treatment day onwards. The number of cells labelled with [3H]thymidine, detected autoradiographically, decreased after treatment with 0.2-10 micrograms/ml by approximately one half on post-treatment day 1 and diminished further by the third day after treatment. The labelled cells were entirely absent only after treatment with 10 micrograms/ml, 7 days post-treatment. Mitoses decreased from 1.4-0.6% by post-treatment day 1 and completely disappeared by day 3 (1 microgram/ml). Feulgen cytophotometry and propidium iodide cytofluorimetry revealed accumulation of cells in the S-phase, especially the latter part (0.5 and 1.0 micrograms/ml, post-treatment day 1) and subsequently also in G2 phase (post-treatment day 3). Incomplete cyto- and karyokinesis in some cycling cells was indicated by an increased number of binucleate cells and nuclei of higher ploidy classes. Labelled cells with intermediate DNA values were, on average, labelled less intensively, as was revealed by simultaneous measurements of DNA content and [3H]thymidine incorporation. Some cells displayed reduction in grain density over heterochromatin clumps. This would be in agreement with the late S-phase block of DNA replication. After post-treatment day 3 the density of cells in cultures was substantially lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Medulloblastoma: histological evaluation and prognosis. A clinical, immunohistochemical and electron microscopic study

Eighty-four cases of medulloblastoma were examined immunohistochemically and 12 by electron microscopy to assess differentiation in these tumors. Based upon the largest series of medulloblastoma studied to date, we demonstrated glial fibrillary acidic protein (GFAP) positivity, in 25% (21/84) of these tumors showing glial differentiation. GFAP-positive cells were seen more frequently in the desmoplastic variant of medulloblastoma (7/10). Under electron microscopy, the major part of the 12 tumors studied appeared primitive and undifferentiated. In 7 cases, groups of cells were found with primitive neuronal and/or glial features. GFAP positivity was confirmed at light microscopy level in all cases where cells showed glial differentiation in the form of glial-like filaments in cytoplasma. However, a follow-up questionnaire study of those patients who had received only surgical treatment revealed no difference in mean survival time between GFAP-positive and GFAP-negative medulloblastoma.