MRI Features of Histologically Diagnosed Supratentorial Primitive Neuroectodermal Tumors and Pineoblastomas in Correlation with Molecular Diagnoses and Outcomes: A Report from the Children's Oncology Group ACNS0332 Trial

BACKGROUND AND PURPOSE

Supratentorial primitive neuroectodermal tumors and pineoblastomas have traditionally been grouped together for treatment purposes. Molecular profiling of these tumors has revealed a number of distinct entities and has led to the term "CNS-primitive neuroectodermal tumors" being removed from the 2016 World Health Organization classification. The purpose of this study was to describe the MR imaging findings of histologically diagnosed primitive neuroectodermal tumors and pineoblastomas and correlate them with molecular diagnoses and outcomes.

MATERIALS AND METHODS

Histologically diagnosed primitive neuroectodermal tumors and pineoblastomas were enrolled in this Children's Oncology Group Phase III trial, and molecular classification was retrospectively completed using DNA methylation profiling. MR imaging features were systematically studied and correlated with molecular diagnoses and survival.

RESULTS

Of the 85 patients enrolled, 56 met the inclusion criteria, in whom 28 tumors were in pineal and 28 in nonpineal locations. Methylation profiling revealed a variety of diagnoses, including pineoblastomas (n = 27), high-grade gliomas (n = 17), embryonal tumors (n = 7), atypical teratoid/rhabdoid tumors (n = 3), and ependymomas (n = 2). Thus, 39% overall and 71% of nonpineal tumor diagnoses were discrepant with histopathology. Tumor location, size, margins, and edema were predictors of embryonal-versus-nonembryonal tumors. Larger size and ill-defined margins correlated with poor event-free survival, while metastatic disease by MR imaging did not.

CONCLUSIONS

In nonpineal locations, only a minority of histologically diagnosed primitive neuroectodermal tumors are embryonal tumors; therefore, high-grade glioma or ependymoma should be high on the radiographic differential. An understanding of molecularly defined tumor entities and their relative frequencies and locations will help the radiologist make more accurate predictions of the tumor types.

Primitive neuroectodermal tumors of the central nervous system

Controversial issues relating to the pathobiology and classification of central nervous system primitive neuroectodermal tumors (PNETs) have plagued neuropathologists for more than 70 years. Hypotheses advanced in the mid-1920's have remained as fixed concepts in contemporary literature, largely consequent to repetitious support by a small number of neuropathologists despite a growing body of information discrediting these ideas from neuroembryologists, oncologists, neuroscientists and pathologists. Attention has largely focused upon PNETs arising in the cerebellum (commonly known as medulloblastomas ([MBs]), because about 80% of central nervous system (CNS) PNETs originate in this site. It has been asserted that the 20% which do not are biologically different, although most individuals agree that the histological features of PNETs that occur in different sites throughout the CNS are indistinguishable from those growing in the cerebellum. The historical aspects of this controversy are examined in the face of evidence that there is, in fact, a unique class of CNS tumors which should appropriately be regarded as primitive neuroectodermal in nature. Specifically, a number of different approaches to the problem have yielded data supporting this hypothesis. These approaches include the identification of patterns of expression among a variety of cellular antigens (demonstrated by the use of immunopathological techniques), molecular analyses of cell lines derived from these tumors, experimental production of PNETs and molecular genetic analyses. Differences of opinion among surgeons, oncologists and radiotherapists are typically resolved by conducting cooperative studies of patients with these tumors who are diagnosed and treated at multiple centers.

CNS germ cell tumor (CNSGCT) of childhood: presentation and delayed diagnosis

OBJECTIVE

To describe the relationship between symptomatology and time to diagnosis of an institutional series of patients with CNS germ cell tumor (CNSGCT) over a 16-year period.

METHODS

Thirty consecutive patients newly diagnosed with CNSGCT (mean age 10.9 years; range 6 to 17 years; 70% boys) were evaluated at our institution between 1990 and 2006.

RESULTS

Duration of symptoms prior to diagnosis ranged from 5 days to 3 years (mean 8.4 months). Tumor location included pineal (14), suprasellar (8), pineal/suprasellar (3), pineal/thalamic (4), and basal ganglionic/thalamic (3). Five patients had disseminated disease at the time of diagnosis. Features including headache, nausea, vomiting, and visual changes led to earlier diagnosis. Symptoms including movement disorders, enuresis, anorexia, and psychiatric complaints delayed diagnosis in 9 of 30 patients, diagnosed 7 months to 3 years (mean 22.3 months) from symptom onset. In 7 of 9 patients with delayed diagnosis, enuresis was present. Seventeen of 30 patients had signs of endocrine dysfunction at presentation that included diabetes insipidus (4), hypothyroidism (8), and growth hormone deficiency (4). Ophthalmologic findings of decreased visual acuity, visual field deficits, or ocular abnormalities were present in 13 patients. Duration of symptoms did not correlate with tumor subtype or event-free survival. In three patients with basal ganglionic/temporal lobe, thalamic, or pineal/suprasellar signal abnormalities on MRI, neuroradiographic diagnosis was difficult.

CONCLUSIONS

Diagnosis of CNS germ cell tumor is often delayed, and presentation may include movement disorders or mimic psychiatric disease. MRI interpretation can be challenging and may require serum/CSF markers and biopsy for diagnosis.

NF1 plexiform neurofibroma growth rate by volumetric MRI: Relationship to age and body weight

OBJECTIVE

To longitudinally analyze changes in plexiform neurofibroma (PN) volume in relation to age and body growth in children and young adults with neurofibromatosis type 1 and inoperable, symptomatic, or progressive PNs, using a sensitive, automated method of volumetric MRI analysis.

METHODS

We included patients 25 years of age and younger with PNs entered in a natural history study or in treatment trials who had volumetric MRI over > or =16 months.

RESULTS

We studied 49 patients (median age 8.3 years) with 61 PNs and a median evaluation period of 34 months (range 18 to 70). The PN growth rates varied among patients, but were constant within patients. Thirty-four patients (69%) experienced > or =20% increase in PN volume during the observation period. PN volume increased more rapidly than body weight over time (p = 0.026). Younger patients had the most rapid PN growth rate.

CONCLUSIONS

Volume increase of plexiform neurofibromas is a realistic and meaningful trial endpoint. In most patients plexiform neurofibroma growth rate exceeded body growth rate. The youngest patients had the fastest plexiform neurofibroma growth rate, and clinical drug development should be directed toward this population. Age stratification for clinical trials for plexiform neurofibromas should be considered.

Phase I study of thalidomide for the treatment of plexiform neurofibroma in neurofibromatosis 1

An open-label phase I trial of thalidomide (TL) in 20 patients with neurofibromatosis 1 (NF1) treated symptomatic plexiform neurofibroma (PNF). TL was well tolerated in doses up to 200 mg/d. Adverse reactions included transient somnolence in four, evanescent rash in two, and reversible mild peripheral neuropathy in two patients. Four patients showed less than 25% reduction in the tumor size. TL may have a role in the treatment of PNF and should be explored in a larger controlled study, possibly using higher doses of TL.

Congenital myasthenic syndrome caused by low-expressor fast-channel AChR delta subunit mutation

OBJECTIVE

To determine the molecular basis of a disabling congenital myasthenic syndrome (CMS) observed in two related and one unrelated Arab kinship.

BACKGROUND

CMS can arise from defects in presynaptic, synaptic basal lamina-associated, or postsynaptic proteins. Most CMS are postsynaptic, and most reside in the AChR epsilon subunit; only two mutations have been reported in the AChR delta subunit to date.

METHODS

Cytochemistry, electron microscopy, alpha-bungarotoxin binding studies, microelectrode and patch-clamp recordings, mutation analysis, mutagenesis, and expression studies in human embryonic kidney cells were employed.

RESULTS

Endplate studies showed AChR deficiency, fast decaying, low-amplitude endplate currents, and abnormally brief channel opening events. Mutation analysis revealed a novel homozygous missense mutation (deltaP250Q) of the penultimate proline in the first transmembrane domain (TMD1) of the AChR delta subunit. Expression studies indicate that deltaP250Q (1) hinders delta/alpha subunit association during early AChR assembly; (2) hinders opening of the doubly occupied closed receptor (A(2)R); and (3) speeds the dissociation of acetylcholine from A(2)R. Mutagenesis studies indicate that deltaP250L also has fast-channel effects, whereas epsilon P245L and epsilon P245Q, identical mutations of the corresponding proline in the epsilon subunit, have mild slow-channel effects.

CONCLUSIONS

deltaP250Q represents the third mutation observed in the AChR delta subunit. The severe phenotype caused by deltaP250Q is attributed to endplate AChR deficiency, fast decay of the synaptic response, and lack of compensatory factors. That the penultimate prolines in TMD1 of the delta and epsilon subunits exert a reciprocal regulatory effect on the length of the channel opening bursts reveals an unexpected functional asymmetry between the two subunits.

Plexiform neurofibromas in NF1: toward biologic-based therapy

Neurofibromatosis type 1 (NF1) is one of the most common neurogenetic diseases affecting adults and children. Neurofibromas are one of the most common of the protean manifestations of NF1. Plexiform neurofibromas, which will frequently cause cosmetic abnormalities, pain, and neurologic deficits, are composed of "neoplastic" Schwann cells accompanied by other participating cellular and noncellular components. There is increasing evidence that loss of NF1 expression in neoplastic Schwann cells is associated with elevated levels of activated RAS, supporting the notion that the NF1 gene product, neurofibromin, acts as a growth regulator by inhibiting ras growth-promoting activity. In addition, there is increasing evidence that other cooperating events, which may be under cytokine modulation, are important for neurofibroma development and growth. Treatment of plexiform neurofibromas has been empiric, with surgery being the primary option for those with progressive lesions causing a major degree of morbidity. The efficacy of alternative treatment approaches, including the use of antihistamines, maturation agents, and antiangiogenic drugs, has been questionable. More recently, biologic-based therapeutic approaches, using drugs that target the molecular genetic underpinnings of plexiform neurofibromas or cytokines believed important in tumor growth, have been initiated. Evaluation of such trials is hindered by the unpredictable natural history of plexiform neurofibromas and difficulties in determining objective response in tumors that are notoriously large and irregular in shape. Innovative neuroimaging techniques and the incorporation of quality-of-life scales may be helpful in evaluation of therapeutic interventions. The ability to design more rational therapies for NF1-associated neurofibromas is heavily predicated on an improved understanding of the molecular and cellular biology of the cells involved in neurofibroma formation and growth.

Medulloblastoma: clinical and biologic aspects

Medulloblastoma is the most common childhood primary CNS tumor, and treatment approaches have evolved over the past three decades. The biologic underpinnings of medulloblastoma are not fully characterized, but recent work has identified new, important directions for research. Stratification of patients with medulloblastoma into risk groups is the backbone of most ongoing therapeutic studies. Patients are usually characterized as being either average risk or poor risk, although an intermediate risk group may exist. Standard treatment for older children with medulloblastoma consists of radiation and, for most, chemotherapy. Children with nondisseminated disease at the time of diagnosis have been reported to have as high as an 80% five-year disease-free survival rate after treatment with reduced dose (2340 cGy) craniospinal irradiation, local boost radiation therapy (5500 cGy), and chemotherapy, given during and after radiation therapy. Preradiation chemotherapy has yet to be shown to be of benefit for children with medulloblastoma. Children with disseminated disease are a highly problematic subgroup of patients to treat. A variety of new approaches are being studied, most of which are intensifying chemotherapy either prior to or after radiation. Long-term survivors of medulloblastoma are at significant risk for permanent endocrinologic, cognitive, and psychological sequelae. Infants and very young children with medulloblastoma remain a difficult therapeutic challenge because they have the most virulent form of the disease and are at highest risk for treatment-related sequelae.

Phase I trial of lobradimil (RMP-7) and carboplatin in children with brain tumors

PURPOSE

To determine the maximum tolerated dose (MTD), the incidence and severity of toxicities, and the pharmacokinetics of lobradimil administered intravenously over 10 min in combination with carboplatin in children with refractory brain tumors.

METHODS

A group of 25 children with primary brain tumors received carboplatin and lobradimil on two consecutive days every 28 days. The 10-min lobradimil infusion began 5 min before the end of the carboplatin infusion. Four lobradimil dose levels (100, 300, 450 and 600 ng/kg ideal body weight, IBW) were studied in cohorts of 4 to 13 patients. Carboplatin was adaptively dosed based on the glomerular filtration rate to achieve a target plasma area under the concentration-time curve (AUC) of 7.0 mg min/ml per course (5.0 mg min/ml for patients who had previously received craniospinal radiation or myeloablative chemotherapy).

RESULTS

Lobradimil toxicity was immediate, tolerable and rapidly reversible. The most frequent toxicities were hypotension, flushing, headache and gastrointestinal complaints. One patient on the 600 ng/kg dose level had a seizure during the lobradimil infusion. The incidence and severity of lobradimil toxicities were not dose-related and the lobradimil dose was not escalated beyond the 600 ng/kg IBW dose level. Two patients had partial responses and ten patients had stable disease. Myelosuppression (thrombocytopenia more prominent than neutropenia) was the primary toxicity attributed to carboplatin. Lobradimil pharmacokinetics were characterized by rapid clearance from the plasma compartment and substantial interpatient variability.

CONCLUSIONS

The combination of carboplatin and lobradimil is safe and tolerable. An MTD for lobradimil was not defined because toxicity was not dose-related. The recommended pediatric phase II dose of lobradimil is 600 ng/kg IBW.

Expression profiling of medulloblastoma: PDGFRA and the RAS/MAPK pathway as therapeutic targets for metastatic disease

Little is known about the genetic regulation of medulloblastoma dissemination, but metastatic medulloblastoma is highly associated with poor outcome. We obtained expression profiles of 23 primary medulloblastomas clinically designated as either metastatic (M+) or non-metastatic (M0) and identified 85 genes whose expression differed significantly between classes. Using a class prediction algorithm based on these genes and a leave-one-out approach, we assigned sample class to these tumors (M+ or M0) with 72% accuracy and to four additional independent tumors with 100% accuracy. We also assigned the metastatic medulloblastoma cell line Daoy to the metastatic class. Notably, platelet-derived growth factor receptor alpha (PDGFRA) and members of the downstream RAS/mitogen-activated protein kinase (MAPK) signal transduction pathway are upregulated in M+ tumors. Immunohistochemical validation on an independent set of tumors shows significant overexpression of PDGFRA in M+ tumors compared to M0 tumors. Using in vitro assays, we show that platelet-derived growth factor alpha (PDGFA) enhances medulloblastoma migration and increases downstream MAP2K1 (MEK1), MAP2K2 (MEK2), MAPK1 (p42 MAPK) and MAPK3 (p44 MAPK) phosphorylation in a dose-dependent manner. Neutralizing antibodies to PDGFRA blocks MAP2K1, MAP2K2 and MAPK1/3 phosphorylation, whereas U0126, a highly specific inhibitor of MAP2K1 and MAP2K2, also blocks MAPK1/3. Both inhibit migration and prevent PDGFA-stimulated migration. These results provide the first insight into the genetic regulation of medulloblastoma metastasis and are the first to suggest a role for PDGFRA and the RAS/MAPK signaling pathway in medulloblastoma metastasis. Inhibitors of PDGFRA and RAS proteins should therefore be considered for investigation as possible novel therapeutic strategies against medulloblastoma.

Prognostic factors and secondary malignancies in childhood medulloblastoma

PURPOSE

Little is known of the outcome of long-term survivors of childhood medulloblastoma, one of the most common pediatric malignancies. To determine the potential for secondary malignancies, a retrospective outcome evaluation in 88 consecutive cases of childhood medulloblastoma was performed.

PATIENTS AND METHODS

The records of all patients with childhood medulloblastoma diagnosed at Children's National Medical Center in Washington, DC from 1969 through 1997 were reviewed.

RESULTS

The median follow-up time was 92 months (range 6-257 months). Overall survival was 59% at 5 years and 52% at 10 years. Univariate analysis showed that age at diagnosis, extent of surgical resection, presence of metastatic disease (M stage), ventriculoperitoneal shunt placement within 30 days from diagnosis, posterior fossa radiation therapy dose, and adjuvant chemotherapy significantly affected survival. Although based on small numbers, the risk of second neoplasms was significantly increased in this cohort. Multiple basal cell carcinomas developed in the areas of radiation therapy in two patients; these patients also had nevoid basal cell carcinoma syndrome (NBCCS) diagnosed. One other patient died of glioblastoma multiforme 8 years after treatment of medulloblastoma. A meningioma developed in another patient 10 years after radiation therapy.

CONCLUSION

As survival of medulloblastoma patients improves, increased surveillance regarding secondary malignancies is required, especially because radiation-induced tumors may occur many years after treatment. These two cases of NBCCS also illustrate the importance of considering the concomitant diagnosis of NBCCS in young patients with medulloblastoma. In those patients, alternative therapy should be considered to minimize radiation therapy-related sequelae.

Intracranial germ cell tumors

Intracranial germ cell tumors are a heterogeneous group of lesions which occur in children and adults. Within the classification of intracranial germ cell tumors, there are a variety of different tumor types which carry different prognoses. The diagnosis of an intracranial germ cell tumor usually requires histological information, but a subgroup of tumors will secrete specific tumor markers, including alpha-fetoprotein and beta-human chorionic gonadotropin, which may obviate the need for surgical intervention. The management of intracranial germ cell tumors in both children and adults remains unsettled. Germinomas have a good prognosis, as over 90% of patients can be effectively treated with radiation therapy. The dose and volume of radiation therapy needed for disease control is not well established, and controversy exists concerning the need for whole brain or craniospinal radiation therapy for localized tumors. Germinomas are also chemosensitive and recent reports suggest that the dose and volume of radiation therapy required for disease control can be lessened with the addition of adjuvant chemotherapy. The outcome for patients with nongerminomatous germ cell tumors is less favorable. Radiation therapy alone will result in disease control in 40%-60% of patients. The addition of chemotherapy to radiation therapy may improve the rate of survival.

Growth hormone replacement therapy in children with medulloblastoma: use and effect on tumor control

PURPOSE

Progress has been made in the treatment of medulloblastoma, the most common childhood malignant brain tumor: However, many long-term survivors will have posttherapy growth hormone insufficiency with resultant linear growth retardation. Growth hormone replacement therapy (GHRT) may significantly improve growth, but there is often reluctance to initiate GHRT because of concerns of an increased likelihood of tumor relapse.

PATIENTS AND METHODS

This study retrospectively reviewed the use of GHRT for survivors of medulloblastoma in 11 neuro-oncology centers in North America who received initial treatment for disease between 1980 and 1993 to determine its impact on disease control. A Landmark analysis was used to evaluate the relative risk of relapse in surviving patients.

RESULTS

Five hundred forty-five consecutive patients less than 15 years of age at diagnosis were identified. Six-year progression-free survival (mean +/- SD) was 40% +/- 5% in children less than 3 years of age at diagnosis compared with 59% +/- 3% for older patients. Older patients with total or near-total resections (P = .003) and localized disease at diagnosis (P < .0001) had the highest likelihood of survival. One hundred seventy patients (33% +/- 3% of the cohort) received GHRT. GHRT use varied widely among institutions, ranging from 5% to 73%. GHRT was begun a mean of 3.9 years after diagnosis, later in children younger than 3 years at diagnosis (5.4 years). By Landmark analyses, for those surviving 2, 3, and 5 years after diagnosis, there was no evidence that GHRT increased the rate of disease relapse.

CONCLUSION

This large retrospective review demonstrates that GHRT is underutilized in survivors of medulloblastoma and is used relatively late in the course of the illness. GHRT is not associated with an increased likelihood of disease relapse.

Correlation of neurosurgical subspecialization with outcomes in children with malignant brain tumors

OBJECTIVE

This study was performed to evaluate the association between the type of neurosurgeon (general or pediatric) and either the extent of tumor removal or the frequency of complications in children undergoing malignant brain tumor resections.

METHODS

Data were analyzed from three recent Children's Cancer Group studies: two on medulloblastomas/primitive neuroectodermal tumors and one on malignant gliomas. Neurosurgeons were classified as general neurosurgeons, as designated pediatric neurosurgeons in their institutions, or as members of the American Society of Pediatric Neurosurgeons (ASPN), which requires pediatric neurosurgical experience and practice standards.

RESULTS

Data forms from 732 children were analyzed; 485 were from children with medulloblastomas/primitive neuroectodermal tumors, and 247 were from children with malignant gliomas. Operations were performed by 269 neurosurgeons, including 213 general neurosurgeons, 29 designated pediatric neurosurgeons, and 27 ASPN members. The mean number of operations per surgeon was 1.8, 4.9, and 7.6 for general neurosurgeons, designated pediatric neurosurgeons, and ASPN members, respectively. There was a significant relationship between the extent of tumor resection or the amount of residual tumor and the type of neurosurgeon. Designated pediatric neurosurgeons and ASPN members were more likely to remove more than 90% of the tumor and to leave less than 1.5 cc of residual tumor than were general neurosurgeons (P<0.05). In these studies, the probability of extensive tumor removal correlated with the number of operations the neurosurgeon performed (P<0.01). Neurological complications occurred in the following proportion of cases: general neurosurgeons, 23%; designated pediatric neurosurgeons, 32%; and ASPN members, 18%.

CONCLUSION

Pediatric neurosurgeons are more likely than general neurosurgeons to extensively remove malignant pediatric brain tumors. In these tumors, extent of removal has been demonstrated to influence survival.

Low-stage medulloblastoma: final analysis of trial comparing standard-dose with reduced-dose neuraxis irradiation

PURPOSE

To evaluate prospectively the effects on survival, relapse-free survival, and patterns of relapse of reduced-dose (23.4 Gy in 13 fractions) compared with standard-dose (36 Gy in 20 fractions) neuraxis irradiation in patients 3 to 21 years of age with low-stage medulloblastoma, minimal postoperative residual disease, and no evidence of neuraxis disease.

PATIENTS AND METHODS

The Pediatric Oncology Group and Children's Cancer Group randomized 126 patients to the study. All patients received posterior fossa irradiation to a total dose of 54 Gy in addition to the neuraxis treatment. Patients were staged postoperatively with contrast-enhanced cranial computed tomography, myelography, and CSF cytology. Of the registered patients, 38 were ineligible.

RESULTS

The planned interim analysis that resulted in closure of the protocol showed that patients randomized to the reduced neuraxis treatment had increased frequency of relapse. In the final analysis, eligible patients receiving standard-dose neuraxis irradiation had 67% event-free survival (EFS) at 5 years (SE = 7.4%), whereas eligible patients receiving reduced-dose neuraxis irradiation had 52% event-free survival at 5 years (SE = 7.7%) (P =.080). At 8 years, the respective EFS proportions were also 67% (SE = 8.8%) and 52% (SE = 11%) (P =.141). These data confirm the original one-sided conclusions but suggest that differences are less marked with time.

CONCLUSION

Reduced-dose neuraxis irradiation (23.4 Gy) is associated with increased risk of early relapse, early isolated neuraxis relapse, and lower 5-year EFS and overall survival than standard irradiation (36 Gy). The 5-year EFS for patients receiving standard-dose irradiation is suboptimal, and improved techniques and/or therapies are needed to improve ultimate outcome. Chemotherapy may contribute to this improvement.

High-dose carmustine, thiotepa and etoposide followed by autologous bone marrow rescue for the treatment of high risk central nervous system tumors

Forty-two patients (29 newly diagnosed) with high grade gliomas (n = 37), medulloblastoma (n = 2) or non-biopsied tumors (n = 3) with supratentorial (n = 24), brain stem (n = 11), posterior fossa (n = 5) or spinal (n = 2) location were eligible for this study with adequate organ function and no bone marrow tumor infiltration. Median patient age was 12.2 years (range, 0.7-46.8). A total of 600 mg/m2 BCNU, 900 mg/m2 thiotepa and 1500 or 750 mg/m2 etoposide (VP-16) was administered followed by autologous bone marrow reinfusion (ABMR). Twenty-one newly diagnosed patients received local irradiation (RT) post ABMR. Nine early deaths were observed (21%), as well as one secondary graft failure. Half of the patients aged 18 years or older experienced toxic deaths, whereas only 15% of patients younger than 18 years experienced toxic death (P = 0.05). Of 25 evaluable newly diagnosed patients, 20% achieved complete remission (CR) and 4% partial remission (PR), while 28% remained in continuing complete remission (CCR) and 44% remained with stable disease prior to RT. Of eight evaluable patients with recurrent disease, one achieved CR and two PR, while one remained in CCR and four with stable disease for 1 to 110.2 months. Overall survival was 36%, 24% and 17% at 1, 2 and 3 years following ABMR, with three newly diagnosed patients and one patient treated for recurrent disease being alive, without disease progression 64.4, 67.0, 86.3 and 110.2 months after ABMR, respectively. The combination of high-dose BCNU/ thiotepa/VP-16 has substantial toxicity but definite activity for high risk CNS tumors. Similar protocols with lower toxicity merit further evaluation in both newly diagnosed and recurrent CNS tumors.

Chemotherapy: low-grade gliomas of the hypothalamus and thalamus

Chemotherapy is an increasing component of the management of diencephalic gliomas. It can result in tumor shrinkage and significant disease control in some patients. However, decisions concerning the institution of treatment should be based on the goals of treatment. Factors include: (1) age of the patient; (2) whether the child has neurofibromatosis type 1; (3) tumor size and location; (4) the potential sequelae of radiotherapy, and (5) the acute and long-term toxicity of the chemotherapeutic approach utilized. The erratic natural history of diencephalic tumors confounds evaluation of efficacy of the regimen chosen.

Outcome for children with supratentorial primitive neuroectodermal tumors treated with surgery, radiation, and chemotherapy

BACKGROUND

The outcome of a child with a primitive neuroectodermal tumors arising supratentorially (SPNET) is not well characterized and may differ from the outcome of a patient with a histologically similar cerebellar tumor (medulloblastoma [MB]). Recently, 5-year progression free survival rates as high as 80% have been reported for children with MB treated with craniospinal radiation (CRT) and chemotherapy including cisplatin, lomustine (CCNU), and vincristine (VCR).

METHODS

The authors reviewed the outcome of 22 consecutive patients age 3 years and older (mean age, 10 years; range, 3-18 years) with SPNET who were treated at the study institutions between 1981 and 1996. Tumor location included was 13 pineal, 6 cortical, and 3 thalamic or suprasellar. Five patients had disease dissemination at diagnosis. All patients underwent surgery and staging, followed by CRT and chemotherapy with cisplatin, CCNU, and VCR.

RESULTS

Of the 22 patients, 13 had developed disease progression and 10 had died at the time of last follow-up. Overall progression free survival (PFS) was 47% +/- 11% at 3 years and 37% +/- 11% at 5 years. There was a significant difference in PFS between patients with localized disease versus those with disseminated disease (P = 0.04). There was no statistical association between tumor location and survival. Although not significant (P = 0.21), there was a trend toward better survival of those patients with complete or near-complete resection compared with those with partial resection or biopsy.

CONCLUSIONS

The results of the current study demonstrate that the outcome for children with SPNET treated with radiation and chemotherapy appears worse than for children with MB treated with identical therapy. This suggests that there may be biologic differences between supratentorial and infratentorial primitive neuroectodermal tumors, thus requiring refinements in treatment.

Treatment of low-grade pediatric gliomas

The prognosis of pediatric low-grade gliomas is relatively favorable, but residual or unresectable tumors remain a challenge. Conventional radiation therapy is effective but may be associated with unacceptable sequelae in young children. Chemotherapy can delay the need for radiation therapy in young children; however, its role in older children has yet to be established. New forms of radiation are being introduced that may be less toxic.

Etoposide with or without mannitol for the treatment of recurrent or primarily unresponsive brain tumors: a Children's Cancer Group Study, CCG-9881

PURPOSE

This study was undertaken to evaluate the response of recurrent brain tumors to intravenous etoposide and to evaluate the efficacy of mannitol in augmenting etoposide's tumoricidal effect.

PATIENTS AND METHODS

Ninety-nine children between one and 21 years of age with recurrent brain tumors were randomly assigned to treatment with intravenous etoposide 150 mg/M2, with or without mannitol 15 gm/M2, daily for five days every three weeks for one year or until disease progression or death. Computerized tomographic (CT) or magnetic resonance image (MRI) scans, obtained after three cycles of therapy, were compared with pre-therapy scans. Scans were centrally reviewed.

RESULTS

Of 87 evaluable patients, 12 (13.8%) were determined to have had an objective response by the institutional radiologist. On central review, 7/66 (10.6%) responses were documented. Responses in centrally reviewed patients were observed in 2/12 (16.7%) low grade astrocytomas, 4/26 (15.4%) medulloblastoma or primitive neuroectodermal tumors (PNET), 1/13 (7.7%) high grade astrocytomas and 0/15 (0%) brain stem gliomas. Survival at one year was 53% (SE 12%) for low grade astrocytomas, 38% (SE 7%) for medulloblastoma or PNET, 28% (SE 10%) for high grade astrocytomas and 9% (SE 5%) for brain stem gliomas. An effect of mannitol was not observed.

CONCLUSION

Intravenous etoposide has a low level of activity in the treatment of recurrent low grade astrocytomas and medulloblastoma or PNET. The efficacy of this agent was not enhanced by the coincident intravenous administration of mannitol.

Spontaneous regression of low-grade astrocytomas in childhood

An 8-year-old boy with neurofibromatosis type 1 (NF1) and a biopsy-proven juvenile pilocytic astrocytoma of the hypothalamic/chiasmatic region was followed with serial MRIs over 4 years. Spontaneous tumor regression was followed by progression and biopsy; 6 months later, the tumor regressed again. This bimodal regression is rare, but highlights the variable natural history of low-grade gliomas in children with NF1 and the difficulty in evaluating response of such tumors to therapy.

Treatment of progressive or recurrent pediatric malignant supratentorial brain tumors with herpes simplex virus thymidine kinase gene vector-producer cells followed by intravenous ganciclovir administration

OBJECT

The outcome for children with recurrent malignant brain tumors is poor. The majority of patients die of progressive disease within months of relapse, and other therapeutic options are needed. The goal of this Phase I study was to evaluate the safety of in vivo suicide gene therapy in 12 children with recurrent, malignant, supratentorial brain tumors.

METHODS

After optimal repeated tumor resection, multiple injections of murine vector-producing cells shedding murine replication-defective retroviral vectors coding the herpes simplex virus thymidine kinase type 1 (HSV-Tk1) gene were made into the rim of the resection cavity. Fourteen days after the vector-producing cells were injected, ganciclovir was administered for 14 days. The retroviral vector that was used only integrated and expressed HSV-Tk1 in proliferating cells, which are killed after a series of metabolic events lead to cell death. The median age of the patients was 11 years (range 2-15 years). Treated brain tumors included seven malignant gliomas, two ependyminomas, and three primitive neuroectodermal tumors. The patients were treated with one of three escalating dose concentrations of vector-producer cells. Four transient central nervous system adverse effects were considered possibly related to the vector-producing cells. In no child did permanent neurological worsening or ventricular irritation develop, and tests for replication-competent retroviruses yielded negative findings.

CONCLUSIONS

This Phase I study demonstrates that in vivo gene therapy in which a replication-defective retroviral vector in murine vector-producing cells is delivered by brain injections can be performed with satisfactory safety in a select group of children with localized supratentorial brain tumors.

Quality of life of adult survivors of germinomas treated with craniospinal irradiation

OBJECTIVE

To assess the quality of life (QOL) of a group of patients treated for intracranial germinoma with biopsy followed by prophylactic whole-neuraxis radiation therapy.

METHODS

The Short-form-36 and Functional Assessment of Cancer Therapy QOL questionnaires were completed by 22 of 27 eligible adults treated with whole-neuraxis irradiation for biopsy-proven, marker-negative intracranial germinomas between 1976 and 1996. In addition, data were obtained regarding height and weight, medications, ability to work, and educational achievement.

RESULTS

The patients' QOL was generally good. All of the patients are in or have completed high school; nine are in or have completed college, and five have advanced degrees. Patients rated themselves lower on the physical composite scale of the Short-form-36 (average, 46 versus 54 in a normal population). On the mental composite scale, patients rated themselves more favorably than the normal population (average, 54 versus 49 in a normal population). Patients were normally proportioned for height and weight, but female patients tended to be short. Age at radiation did not correlate with QOL.

CONCLUSION

The QOL of adults treated for marker-negative germinoma with prophylactic whole-neuraxis irradiation is generally good. These data should serve as a benchmark for newer treatment protocols eliminating or reducing radiation.

Medulloblastoma

The utilization of multi-modal therapy in the treatment of medulloblastoma has improved survival rates and overall outcome. Recent large clinical trials have supported the use of radiation and chemotherapy as adjuvant treatment. Treatment advances have been made despite a poor understanding of the biological underpinnings of medulloblastoma. Current laboratory investigations are shedding light on the oncogenesis of medulloblastoma and may lead to improved treatments.

Alternative treatments for childhood brain tumors

The treatment options for children with brain tumors are quite limited. Advances in tumor biology and neuroscience have opened new avenues of treatment. New approaches include gene therapy, agents designed to interfere with signal transduction, antiangiogenesis drugs, maturation agents, immunotherapy, and immunoconjugates. New means of drug/agent delivery, including drugs that selectively open the tumor-blood barrier and convection-infusional approaches, are under study. Such innovative treatments will be more widely employed in the years ahead and may improve outcome for children with brain tumors.

Primary Central Nervous System Tumors in Children

The standard treatment for children with medulloblastoma, especially those who are older than 3 years of age at the time of diagnosis, includes craniospinal radiation therapy, local radiation therapy, and chemotherapy during and after radiation therapy. The benefits of administering chemotherapy before radiation therapy are unproven, and this approach may result in overall poorer disease control because it delays the initiation of radiation therapy. The amount of radiation therapy needed in patients with nondisseminated disease is unclear. The treatment of children younger than 3 years of age with medulloblastoma is discussed later in this article. The management of brain stem gliomas is currently far from optimal. Surgery has no role in either the diagnosis or the treatment of diffuse intrinsic tumors. Radiation therapy remains the standard treatment for patients with diffuse intrinsic tumors, although the majority die within 18 months of diagnosis. The optimal treatment for exophytic cervicomedullary lesions has yet to be determined. Although surgical resection can result in disease control in many patients, it is often associated with increased neurologic morbidity. Alternative treatments, such as partial resection, followed by focused radiation therapy or chemotherapy may be as effective as complete resection in controlling disease and may result in less morbidity. The treatment of childhood low-grade gliomas is complex, and both the histologic subtype of the tumor and its location must be considered. For some tumors, especially cerebellar astrocytomas, the treatment of choice is total surgical resection. For tumors that are not amenable to gross total resection, radiation therapy remains the standard treatment. Focused radiation therapy may, in time, be significant in the management of children with low-grade tumors, but it is not clear whether such therapy will control the leading edge of the tumor or cause excessive neurologic morbidity. Chemotherapy is being used more and more frequently for children with low-grade gliomas. For the majority of children, it is used to delay the need for more definitive therapy, such as radiation therapy or more aggressive surgical resection. In this regard, it is unclear whether more aggressive chemotherapy is of greater long-term benefit than less aggressive regimens for patients with low-grade gliomas. Clear-cut evidence indicates that chemotherapy, especially the combination of carboplatin and vincristine, is active in low-grade gliomas and delays the need for radiation therapy in the majority of children younger than 5 years of age. The role of chemotherapy in older children is poorly defined. Currently, the standard treatment for children with high-grade gliomas probably includes radiation therapy and chemotherapy with CCNU plus vincristine. Studies are using chemotherapy before radiation therapy in attempts to identify active agents in this disease type. Other active subjects of investigation include the use of high-dose chemotherapy after radiation therapy for children with newly diagnosed disease and the use of radiosensitization agents.

Chemotherapy for low-grade gliomas

Low-grade gliomas are the most common histological type of pediatric brain tumor. They can arise in any part of the nervous system. Although low-grade gliomas are slow growing, they often recur or progress, especially in areas such as the diencephalon or brain stem, where resection is limited by proximity to vital and eloquent structures. Radiation has been used to treat progressive low-grade gliomas, but it is not clear that it improves long-term outcome. Radiotherapy also has potential significant cognitive, endocrine, and vascular side- effects. There is a growing body of evidence to suggest that chemotherapy can delay and may obviate the need for radiation therapy or aggressive surgery. This chapter reviews the published chemotherapeutic trials. Chemotherapy appears to have a major role in the management of children with progressive low-grade gliomas.

Treatment strategies for medulloblastoma and primitive neuroectodermal tumors

Medulloblastoma and primitive neuroectodermal tumors (PNETs) are the most common malignant brain tumors in children. The concern for late sequelae of neuraxis irradiation and the obligation to improve disease-free survival in children who harbor malignant brain tumors has led to the additional provision of systemic chemotherapy to standard- and reduced-dose radiotherapy, as well as to the evaluation of alternate modes of radiotherapy delivery. Analysis of evidence has suggested that chemotherapy has an impact on length of survival in children with medulloblastoma and PNETs. The question remains as to whether chemotherapy combined with reduced-dose radiotherapy provides greater benefit than standard-dose radiotherapy alone, and which subset of children the treatment most benefits. Also unanswered is the question of whether chemotherapy can serve as the primary treatment in infants with these lesions. In an attempt to help answer these questions, the authors review the major chemotherapy and radiotherapy trials for newly diagnosed patients and those with recurrent medulloblastoma and PNETs.

Treatment of children with medulloblastomas with reduced-dose craniospinal radiation therapy and adjuvant chemotherapy: A Children's Cancer Group Study

PURPOSE

Medulloblastoma is the most common malignant brain tumor of childhood. After treatment with surgery and radiation therapy, approximately 60% of children with medulloblastoma are alive and free of progressive disease 5 years after diagnosis, but many have significant neurocognitive sequelae. This study was undertaken to determine the feasibility and efficacy of treating children with nondisseminated medulloblastoma with reduced-dose craniospinal radiotherapy plus adjuvant chemotherapy.

PATIENTS AND METHODS

Over a 3-year period, 65 children between 3 and 10 years of age with nondisseminated medulloblastoma were treated with postoperative, reduced-dose craniospinal radiation therapy (23.4 Gy) and 55.8 Gy of local radiation therapy. Adjuvant vincristine chemotherapy was administered during radiotherapy, and lomustine, vincristine, and cisplatin chemotherapy was administered during and after radiation.

RESULTS

Progression-free survival was 86% +/- 4% at 3 years and 79% +/- 7% at 5 years. Sites of relapse for the 14 patients who developed progressive disease included the local tumor site alone in two patients, local tumor site and disseminated disease in nine, and nonprimary sites in three. Brainstem involvement did not adversely affect outcome. Therapy was relatively well tolerated; however, the dose of cisplatin had to be modified in more than 50% of patients before the completion of treatment. One child died of pneumonitis and sepsis during treatment.

CONCLUSION

These overall survival rates compare favorably to those obtained in studies using full-dose radiation therapy alone or radiation therapy plus chemotherapy. The results suggest that reduced-dose craniospinal radiation therapy and adjuvant chemotherapy during and after radiation is a feasible approach for children with nondisseminated medulloblastoma.

Medulloblastoma: clinical and biologic aspects

Medulloblastoma is the most common childhood primary CNS tumor, and treatment approaches have evolved over the past three decades. The biologic underpinnings of medulloblastoma are not fully characterized, but recent work has identified new, important directions for research. Stratification of patients with medulloblastoma into risk groups is the backbone of most ongoing therapeutic studies. Patients are usually characterized as being either average risk or poor risk, although an intermediate risk group may exist. Standard treatment for older children with medulloblastoma consists of radiation and, for most, chemotherapy. Children with nondisseminated disease at the time of diagnosis have been reported to have as high as an 80% five-year disease-free survival rate after treatment with reduced dose (2340 cGy) craniospinal irradiation, local boost radiation therapy (5500 cGy), and chemotherapy, given during and after radiation therapy. Preradiation chemotherapy has yet to be shown to be of benefit for children with medulloblastoma. Children with disseminated disease are a highly problematic subgroup of patients to treat. A variety of new approaches are being studied, most of which are intensifying chemotherapy either prior to or after radiation. Long-term survivors of medulloblastoma are at significant risk for permanent endocrinologic, cognitive, and psychological sequelae. Infants and very young children with medulloblastoma remain a difficult therapeutic challenge because they have the most virulent form of the disease and are at highest risk for treatment-related sequelae.

Prothrombin G20210A mutation in a child with spinal cord infarction

Prothrombin G20210A is a newly described common mutation that is associated with an increased risk of arterial and venous thrombosis. We describe a healthy child heterozygous for this prothrombin mutation who had a spinal cord infarct with no other prothrombotic risk factors.

Brain tumors in children

Childhood brain tumors are the leading cause of cancer-related morbidity and mortality in the pediatric years and differ from primary central nervous system tumors occurring in adults. Management strategies must take into account not only the tumor type, but the age of the patient and the likelihood of treatment-induced nervous system damage. With current means of treatment, most children older than 3 years can be effectively treated. Chemotherapy has taken on an increasing role in the treatment of childhood medulloblastomas, low-grade gliomas, and high-grade gliomas. Some tumor types, especially atypical teratoid tumors, brainstem gliomas, malignant gliomas, and malignant infantile tumors, remain significant therapeutic dilemmas.

Metastasis stage, adjuvant treatment, and residual tumor are prognostic factors for medulloblastoma in children: conclusions from the Children's Cancer Group 921 randomized phase III study

PURPOSE

From 1986 to 1992, "eight-drugs-in-one-day" (8-in-1) chemotherapy both before and after radiation therapy (XRT) (54 Gy tumor/36 Gy neuraxis) was compared with vincristine, lomustine (CCNU), and prednisone (VCP) after XRT in children with untreated, high-stage medulloblastoma (MB).

PATIENTS AND METHODS

Two hundred three eligible patients with an institutional diagnosis of MB were stratified by local invasion and metastatic stage (Chang T/M) and randomized to therapy. Median time at risk from study entry was 7.0 years.

RESULTS

Survival and progression-free survival (PFS) +/- SE at 7 years were 55%+/-5% and 54%+/-5%, respectively. VCP was superior to 8-in-1 chemotherapy, with 5-year PFS rates of 63%+/-5% versus 45%+/-5%, respectively (P = .006). Upon central neuropathology review, 188 patients were confirmed as having MB and were the subjects for analyses of prognostic factors. Children aged 1.5 to younger than 3 years had inferior 5-year estimates of PFS, compared with children 3 years old or older (P = .0014; 32%+/-10% v 58%+/-4%, respectively). For MB patients 3 years of age or older, the prognostic effect of tumor spread (MO v M1 v M2+) on PFS was powerful (P = .0006); 5-year PFS rates were 70%+/-5%, 57%+/-10%, and 40%+/-8%, respectively. PFS distributions at 5 years for patients with M0 tumors with less than 1.5 cm2 of residual tumor, versus > or = 1.5 cm2 of residual tumor by scan, were significantly different (P = .023; 78%+/-6% v 54%+/-11%, respectively).

CONCLUSION

VCP plus XRT is a superior adjuvant combination compared with 8-in-1 chemotherapy plus XRT. For patients with M0 tumors, residual tumor bulk (not extent of resection) is a predictor for PFS. Patients with M0 tumors, > or = 3 years with < or = 1.5 cm2 residual tumor, had a 78%+/-6% 5-year PFS rate. Children younger than 3 years old who received a reduced XRT dosage had the lowest survival rate.