Radiotherapy, Especially at Young Age, Increases the Risk for De Novo Brain Tumors in Patients Treated for Pituitary/Sellar Lesions

CONTEXT

De novo brain tumors developing after treatment of pituitary/sellar lesions have been reported, but it is unknown whether this is linked to any of the treatment modalities.

OBJECTIVE

To study the occurrence of malignant brain tumors and meningiomas in a large cohort of patients treated for pituitary/sellar lesions, with special emphasis on the role of radiotherapy (RT).

PATIENTS AND METHODS

Patients (n = 8917) who were hypopituitary due to pituitary adenomas, craniopharyngiomas, and other sellar tumors followed in KIMS (Pfizer International Metabolic Database) from 1994 to 2012 were included. Treatment consisted of surgery and/or medical therapy in 4927 patients, RT alone, or with surgery in 3236 patients; data were missing in 754. Incidence rate ratios (RRs) were analyzed through Poisson regression methods with internal comparisons.

RESULTS

During 53,786 patient-years, 17 cases of malignant brain tumors (13 exposed to RT) and 27 meningiomas (22 exposed to RT) were reported. RR for RT vs no RT was 3.34 [95% confidence interval (CI), 1.06 to 10.6] for malignant brain tumors, and 4.06 (95% CI, 1.51 to 10.9) for meningiomas. The risk of developing a malignant brain tumor increased by 2.4-fold (P = 0.005) and meningioma by 1.6-fold with every 10 years of younger age at RT (P = 0.05). Incidence rates were similar in patients treated with conventional RT compared with stereotactic RT.

CONCLUSION

RT of pituitary tumors is associated with increased risk of developing malignant brain tumors and meningiomas, especially when given at younger ages. In balancing risks and benefits of RT, our findings emphasize that special consideration should be given to the age of the patient.

Oligodendrogliomas: clinical significance of 1p and 19q chromosomal deletions

Oligodendrogliomas are a distinct subgroup of brain tumors with a fairly favorable clinical prognosis. However, these tumor exhibit varying degrees of heterogeneity and their clinical behavior is therefore not always the same. For this reason, genetic markers have been developed to further guide the clinical treatment. One such marker, the 1p and 19q chromosomal deletions, has been well documented in a subset of patients with oligodendrogliomas. Most importantly, patients who exhibit these chromosomal deletions respond favorably to chemotherapy. This article reviews the evidence describing the association of such deletions with a favorable response to chemotherapy and improved prognosis of patients with oligodendrogliomas. In addition, attempts to elucidate the molecular mechanisms behind the biologic behavior of these tumors are further explored.

[Occurrence and molecular pathology of high grade gliomas]

BACKGROUND

Glial tumours represent the most frequent type of primary brain cancers. Gliomas are characterized by heterogeneity that makes the diagnosis, histological classification and the choosing of correct therapy more difficult. Despite the advances in developing therapeutic strategies patients with malignant gliomas have a poor prognosis; therefore glial tumours represent one of the most important areas of cancer research. There are no detailed data on the epidemiology of gliomas in Hungary.

METHODS

In the first section of our publication, we analysed the histological diagnosed cases between 2007 and 2011 at the Institute of Pathology, University of Debrecen Medical and Health Science Centre. We analyzed the incidence of 214 high-grade gliomas by tumor grades, gender, age, and the anatomical localization.

RESULTS

The majority of cases were glioblastoma (182 cases), and the remaining 32 cases were anaplastic gliomas. The mean age of patients was 57 years (+/- 16.4), and the male:female ratio was 1.1:1. The most frequent area of tumors was the frontal lobe followed by the temporal, parietal and occipital lobe. We include new findings published recently about glioma pathogenesis, molecular pathways, mutant genes and chromosomal regions. We explain briefly the role of selected important genes in glioma genesis and give an update on knowledge provided by modern molecular methods, which could beneficially influence future therapy and the diagnosis of gliomas.

[Occurrence and molecular pathology of low grade gliomas]

BACKGROUND

The WHO grade I. and II. low-grade gliomas represent nearly the 15% of all primary brain tumors. These tumours contain clinically, histologically and molecularly distinct tumor types. According to their histologic characteristic, grade II glial tumours are the diffuse astrocytoma, oligodendroglioma and oligoastrocytoma subgroups; ependymal tumors are not included in this study.

METHODS

In our publication, we analysed the histologically diagnosed glioma cases between 2007 and 2011 at our institution.

RESULTS

Low-grade gliomas were diagnosed in 127 cases (62 male / 65 female), and the mean ages were 39 years (+/- 20.3). More than half of the cancers were localized in the frontal lobe, and the second most frequent area was the temporal lobe. Finally, we complete our report with an overview of major molecular pathways in low-grade gliomas.

Epidemiology of central nervous system tumors in Karlovac area (Croatia), 1995-2010

The aim of this study was to provide an overview of the central nervous system (CNS) tumours epidemiology in Karlovac region, over the 1995-2010 period. We analyzed data on 359 patients (194 men and 165 women), diagnosed with CNS tumours according to the World Health Organization's diagnostic criteria, in period 1995-2010. The data were obtained from the Neurology and Neurosurgery Department, including other medical records. The data were analysed with t-test and chi-square test. A total of 359 cases of tumours in CNS were recorded for the period of 1995-2010, with slight predominance of men (194;54.0%) over women (165;46.0%). Under the assumption of gender equality, we did not detect a significant gender difference in tumour diagnosis (p = 0.279). Mean age at the diagnosis was 64.1 +/- 12.6 years, with significant gender difference: mean age at diagnosis for men was 62.8 +/- 11.6 years, while for women it was 65.7 +/- 13.5 (p = 0.029). The commonest type of all tumours was metastases (144;40.1%). When only primary tumours were analysed, the commonest type was glioblastoma (125;58.15%), followed by meningeoma (44;20.5%). The remaining types were much less frequent, with i.e. 5 recorded cases of the following three types: astrocytoma, ependimoma and oligodendroglyoma (2.3%). These results suggest a commonly encountered epidemiological profile in the region, with commonest metastases, and glioblastoma as the most common primary tumour. Due to difficulties related to patient gravitating hospitals admittance and overall small sample size for more detailed analyses, it remains for future studies to determine potential association of the Homeland war (1991-1995) and the occurrence of CNS tumours.

Risk factors for oligodendroglial tumors: a pooled international study

Oligodendroglial tumors are rare subtypes of brain tumors and are often combined with other glial tumors in epidemiological analyses. However, different demographic associations and clinical characteristics suggest potentially different risk factors. The purpose of this study was to investigate possible risk factors for oligodendroglial tumors (including oligodendroglioma, anaplastic oligodendroglioma, and mixed glioma). Data from 7 case-control studies (5 US and 2 Scandinavian) were pooled. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for age group, gender, and study site. Data on 617 cases and 1260 controls were available for analyses. Using data from all 7 studies, history of allergies and/or asthma was associated with a decreased risk of anaplastic oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9), and history of asthma only was associated with a decreased risk of oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) and anaplastic oligodendroglioma (OR = 0.3; 95% CI: 0.1-0.9). A family history of brain tumors was associated with an increased risk of anaplastic oligodendroglioma (OR = 2.2; 95% CI: 1.1-4.5). Having had chicken pox was associated with a decreased risk of oligodendroglioma (OR = 0.6; 95% CI: 0.4-0.9) and anaplastic oligodendroglioma (OR = 0.5; 95% CI: 0.3-0.9) in the US studies. Although there is some overlap in risk factors between oligodendroglial tumors and gliomas as a group, it is likely that additional factors specific to oligodendroglial tumors have yet to be identified. Large, multi-institution international studies will be necessary to better characterize these etiological risk factors.

Stable incidence of childhood and adult glioma in The Netherlands, 1989-2003

Time trends in the incidence of glioma may reflect changes in the prevalence of environmental risk factors for glioma. We therefore investigated trends in the incidence of childhood and adult glioma in The Netherlands from 1989 to 2003. We used population-based incidence data from the Netherlands Cancer Registry. We calculated European standardised incidence rates for glioma, and stratified for age, gender and glioma subgroups. Changes in the incidence were estimated by calculating the Estimated Annual Percentage Change. Similar to other countries, the overall incidence of glioma was fairly stable in The Netherlands during the period 1989 to 2003, for both children and adults. In adult astrocytic glioma, a significantly increasing incidence of high-grade astrocytoma was balanced by simultaneous decreases of low-grade astrocytoma, astrocytoma with unknown malignancy grade and glioma of uncertain histology. Most of these time trends can be explained by improving detection and diagnostic precision. Stable incidence rates of adult and childhood glioma suggest that no major changes in environmental risk factors have occurred, which influenced the incidence of glioma in the studied period.

The Austrian Brain Tumour Registry: a cooperative way to establish a population-based brain tumour registry

In Austria, registration of malignant brain tumours is legally mandatory, whereas benign and borderline tumours are not reported. The Austrian Brain Tumour Registry (ABTR) was initiated under the auspices of the Austrian Society of Neuropathology for the registration of malignant and non-malignant brain tumours. All Austrian neuropathology units involved in brain tumour diagnostics contribute data on primary brain tumours. Non-microscopically verified cases are added by the Austrian National Cancer Registry to ensure a population-based dataset. In 2005, we registered a total of 1,688 newly diagnosed primary brain tumours in a population of 8.2 million inhabitants with an overall age-adjusted incidence rate of 18.1/100,000 person-years. Non-malignant cases constituted 866 cases (51.3%). The incidence rate was higher in females (18.6/100,000) as compared to males (17.8/100,000), while 95/1,688 (5.6%) cases were diagnosed in children (<18 years). The most common histology was meningioma (n = 504, 29.9%) followed by glioblastoma (n = 340, 20.1%) and pituitary adenoma (n = 151, 8.9%). Comparison with the Central Brain Tumor Registry of the United States (CBTRUS) database showed high congruency of findings. The ABTR model led by neuropathologists in collaboration with epidemiologists and the Austrian National Cancer Registry presents a cooperative way to establish a population-based brain tumour registry with high quality data. This setting links cancer registration to the mission of medical practice and research as defined by the World Medical Association in the Declaration of Helsinki. The continued operation of ABTR will aid in monitoring changes in incidence and in identifying regional disease clusters or geographic variations in brain tumour morbidity/mortality.

Occurrence of anaplastic oligodendroglioma in a patient with Williams syndrome: a case report with analysis of mutational profile of tumor

Williams syndrome is a rare congenital developmental disorder characterized by a constellation of distinctive facial dysmorphisms, mental retardation, cardiovascular anomalies, infantile hypercalcemia, delayed developmental milestones, dental and musculoskeletal anomalies and distinctive personality traits. A majority of patients with Williams syndrome exhibit a hemizygous micro-deletion of chromosome 7q11.23, which is the locus of some 20-30 genes including the ELN gene that encodes the structural protein elastin. Chromosome 7q contains putative tumor suppressor genes and is one of the chromosomes that are frequently involved in chromosomal aberrations in human malignancies. A paucity of tumors (three) has been reported in the literature to occur in patients with Williams syndrome. We report a case of anaplastic oligodendroglioma that occurred in a 31-year-old man with Williams syndrome. Mutational profiling by loss of heterozygosity analysis using a panel of polymorphic micro-satellite markers indicated combined deletion of chromosome 1p and 19q. We draw attention to this apparently rare or possibly under-reported occurrence of tumors in patients with Williams syndrome and suggest that Central Nervous System [CNS] tumors be considered as differential diagnoses in such patients when they present with unanticipated neurologic symptoms that are not attributable to those commonly associated with Williams syndrome.

Space-time clustering of glioma cannot be attributed to specific histological subgroups

We previously showed that infectious exposures may be involved in the aetiology of adult glioma, by analysing for space-time clustering using population-based data from the South of the Netherlands. Here we extended these analyses and describe in detail the space-time clustering patterns in glioma subgroups, gender and age-categories. Knox tests for space-time interactions between cases were applied with fixed thresholds of close in space, <5 km, and close in time, <1 year apart. We used the spatial coordinates of the addresses at diagnosis in the analyses. Tests were repeated replacing geographical distance with distance to the Nth nearest neighbour. N was chosen such that the mean distance was 5 km. Data were also analysed by a second order procedure based on K-functions. There was only statistically significant space-time clustering for oligodendroglioma. Clustering was present for adults aged 30-54 years and was more pronounced among males. Given the low prior probability of an infectious aetiology for this specific subgroup, these results should probably be interpreted as false-positive. We conclude that space-time clustering of glioma cannot be attributed to a specific glioma subgroup. The observed clustering in our previous study is therefore probably an overall effect within and between glioma subgroups.

Temozolomide Treatment of Refractory Epilepsy in a Patient with an Oligodendroglioma

A 40-year-old man with a left frontotemporal grade II oligodendroglioma developed seizures that were refractory to 14 antiepileptic medications, the ketogenic diet, and epilepsy surgery. With temozolomide therapy, his seizure frequency gradually changed from 30 partial seizures per day to a single simple partial seizure in 6 months. No additional therapeutic measures were introduced during this time. This reduction in seizure frequency appears attributable solely to temozolomide therapy.

Trends in brain cancer incidence and survival in the United States: Surveillance, Epidemiology, and End Results Program, 1973 to 2001

OBJECT

An increasing incidence of brain cancer has been reported for the last three decades. In this study of brain cancer incidence and patient survival in the US, the authors attempt to update information on trends by examining data provided by the Surveillance, Epidemiology, and End Results (SEER) Program.

METHODS

Population-based data from the SEER Program were used to calculate the incidence of and survival rates for people with brain cancer. The approximate Poisson method was used to calculate relative risks for brain cancer and to determine a 95% confidence interval. Annual age-standardized incidence rates were calculated, and time-trend analysis was conducted using joinpoint regression analysis. The relative risks of brain cancer were 1.48 for men compared with women, 3.18 for elderly persons compared with young adults, 1.86 for Caucasian patients compared with African-American patients, and 1.35 for those in metropolitan counties compared with those in nonmetropolitan counties. The incidence of brain cancer increased until 1987, when the annual percentage of change reversed direction, decreasing from 1.68 to 20.44%. The elderly experienced an increase until 1985, but their rates were stable thereafter. Rising trends were noticed for glioblastoma multiforme (GBM), oligodendroglioma, anaplastic astrocytoma, medulloblastoma, and mixed glioma, and falling trends were observed for astrocytoma not otherwise specified and malignant glioma. The survival rate for patients with GBM has not shown improvement in the last two decades.

CONCLUSIONS

Increased risk of brain cancer is associated with being male, Caucasian, elderly, and residing in a metropolitan county. The incidence rate of brain cancer in the US is gradually declining, but the rising trend of GBM combined with its poor survival rate is disconcerting and needs further exploration.

From the archives of the AFIP: Oligodendroglioma and its variants: radiologic-pathologic correlation

Oligodendroglioma is the third most common glial neoplasm and most commonly arises in the frontal lobe. It occurs in males more frequently, and the peak manifestation is during the 5th and 6th decades. Children are affected much less commonly. The clinical presentation is often of several years duration with most patients presenting with seizures, reflecting the strong predilection of this tumor to involve the cortical gray matter. Current histopathologic classification schemes recognize two main types of tumors: well-differentiated oligodendroglioma and its anaplastic variant. Less commonly, neoplastic mixtures of both oligodendroglial and astrocytic components occur and are termed oligoastrocytomas, with both well-differentiated and anaplastic forms. Surgical resection is the mainstay of initial treatment, and many patients experience a long progression-free period. Recent genotyping has revealed chromosomal loss of 1p and 19q as a genetic signature in most oligodendrogliomas, and these tumors respond favorably to chemotherapy. Hence, radiation therapy is now generally reserved for partially resected tumors and cases that failed to benefit from chemotherapy. At cross-sectional imaging, the tumor characteristically involves the cortical gray matter and frequently contains calcification. Robust enhancement is not a common feature and suggests transformation to a higher histologic grade. Advanced magnetic resonance imaging techniques and metabolic imaging play increasingly important roles in both pre- and postoperative assessment of these complex neoplasms.

An update on oligodendroglial neoplasms

PURPOSE OF REVIEW

The most widely accepted brain tumor classification system remains morphology-based but the increasing knowledge of the molecular pathogenesis of oligodendroglial tumors has spurred translational research yielding new diagnostic and therapeutic paradigms. These data have accumulated rapidly and, in combination with exciting new insights in the cellular origin of these tumors, necessitate a review.

RECENT FINDINGS

'Cancer stem cells' have been identified in gliomas. Further study of these cells will not only provide information on the cellular origin and pathogenesis of these tumors but may also give rise to new treatments that target a cell pool not amenable to current therapeutic strategies. Molecular tumor characteristics have been correlated with imaging findings, treatment response and prognosis. This has enabled neuro-oncologists to take a risk-stratified approach to patients with oligodendrogliomas that optimizes treatment efficacy and minimizes toxicity. Furthermore, more accurate epidemiological data have become available from population-based studies.

SUMMARY

In spite of remarkable progress over the last 15 years, these tumors remain incurable. The search for a cure has to go on, while currently available multidisciplinary treatments are refined.

Canine Intracranial Primary Neoplasia: 173 Cases (1986–2003)

This study investigates the clinical and pathologic findings associated with 173 primary brain tumors in our hospital population of dogs that presented between the years 1986 and 2002. Of the 173 primary brain tumors, 78 (45%) were meningiomas, 29 (17%) were astrocytomas, 25 (14%) were oligodendrogliomas, 12 (7%) were choroid plexus tumors, and 7 (4%) were primary central nervous system lymphomas. Smaller numbers of glioblastomas (n = 5), primitive neuroectodermal tumors (n = 5), histiocytic sarcomas (n = 5), vascular hamartomas (n = 4), and unclassified gliomas (n = 3) were identified. One dog had both a meningioma and an astrocytoma. Most tumors were located within the telencephalon, and seizures were the most common clinical presenting complaint. Of 168 tumors for which a location in the brain was recorded at postmortem examination, 79 were found to involve more than 1 brain division. Other neoplasms unrelated to the primary brain tumor were identified on postmortem examination in 39 dogs (23%). Intrathoracic and intraabdominal neoplasms were present at necropsy in 13 and 24 cases, respectively. Based on the results of this study, thoracic radiographs and abdominal ultrasonography may be indicated to look for extracranial neoplasia prior to advanced imaging of the brain or intracranial surgery.

Oligodendroglioma: clinical study and survival analysis correlated with chromosomal anomalies

Object

Demonstration of the loss of chromosomes 1p and 19q in the presence of a brain neoplasm marks the emergence of genotype as a prognostic indicator. The authors report gene expression data for oligodendroglioma and correlate genotype with response to therapy. Gene expression subgroups may represent distinct types of disease.

Methods

Eighty-seven cases of supratentorial oligodendroglioma were selected from 145 cases treated in a single center between January 1990 and December 2001. Fluorescence in situ hybridization was used to determine the status of chromosomes 1p and 19q. Parameters evaluated included clinical data and radiological and histological features. Univariate and multivariate analyses were performed and a probability value less than 0.05 was considered significant.

The patients included 48 women and 39 men. The overall mean age at presentation was 45 years for women and 36 years for men (p = 0.006). The univariate analysis identified the following as favorable prognostic factors: younger patient age (p = 10−5), female sex (p = 0.0025), seizure as a presenting symptom (p = 10−5), normal clinical examination (p = 10−5), absence of lesion enhancement on neuroimaging studies (p = 0.0231), lack of histological necrosis (p = 0.0003), absence of mitoses (p = 0.0014), 1p and 19q deletions (p = 0.0001), absence of recurrence (p = 0.0021), and adjuvant radiotherapy and/or chemotherapy (p = 10−5). The multivariate analysis identified patient age (p = 10−5) and chromosomal anomalies (p = 0.002) as independently linked to survival. Three molecular subtypes emerged: oligodendroglioma with 1p and 19q deletions, oligodendroglioma demonstrating polysomia and a lack of meaningful response to radiotherapy or chemotherapy, and oligodendroglioma with no 1p-9q deletion in which partial response was seen.

Conclusions

According to our data, oligodendrogliomas could be divided into three molecular subtypes. Although chemotherapy seems efficient for managing this tumor, additional studies should be conducted to compare the efficacy of radiotherapy and chemotherapy.

Population-Based Studies on Incidence, Survival Rates, and Genetic Alterations in Astrocytic and Oligodendroglial Gliomas

Published data on prognostic and predictive factors in patients with gliomas are largely based on clinical trials and hospital-based studies. This review summarizes data on incidence rates, survival, and genetic alterations from population-based studies of astrocytic and oligodendrogliomas that were carried out in the Canton of Zurich, Switzerland (approximately 1.16 million inhabitants). A total of 987 cases were diagnosed between 1980 and 1994 and patients were followed up at least until 1999. While survival rates for pilocytic astrocytomas were excellent (96% at 10 years), the prognosis of diffusely infiltrating gliomas was poorer, with median survival times (MST) of 5.6 years for low-grade astrocytoma WHO grade II, 1.6 years for anaplastic astrocytoma grade III, and 0.4 years for glioblastoma. For oligodendrogliomas the MSTwas 11.6 years for grade II and 3.5 years for grade III. TP53 mutations were most frequent in gemistocytic astrocytomas (88%), followed by fibrillary astrocytomas (53%) and oligoastrocytomas (44%), but infrequent (13%) in oligodendrogliomas. LOH 1p/19q typically occurred in tumors without TP53 mutations and were most frequent in oligodendrogliomas (69%), followed by oligoastrocytomas (45%), but were rare in fibrillary astrocytomas (7%) and absent in gemistocytic astrocytomas. Glioblastomas were most frequent (3.55 cases per 100,000 persons per year) adjusted to the European Standard Population, amounting to 69% of total incident cases. Observed survival rates were 42.4% at 6 months, 17.7% at one year, and 3.3% at 2 years. For all age groups, survival was inversely correlated with age, ranging from an MST of 8.8 months (<50 years) to 1.6 months (>80 years). In glioblastomas, LOH 10q was the most frequent genetic alteration (69%), followed by EGFR amplification (34%), TP53 mutations (31%), p16INK4a deletion (31%), and PTEN mutations (24%). LOH 10q occurred in association with any of the other genetic alterations, and was the only alteration associated with shorter survival of glioblastoma patients. Primary (de novo) glioblastomas prevailed (95%), while secondary glioblastomas that progressed from low-grade or anaplastic gliomas were rare (5%). Secondary glioblastomas were characterized by frequent LOH 10q (63%) and TP53 mutations (65%). Of the TP53 mutations in secondary glioblastomas, 57% were in hot-spot codons 248 and 273, while in primary glioblastomas, mutations were more evenly distributed. G:C-->A:T mutations at CpG sites were more frequent in secondary than primary glioblastomas, suggesting that the acquisition of TP53 mutations in these glioblastoma subtypes may occur through different mechanisms.

Population-based study on incidence, survival rates, and genetic alterations of low-grade diffuse astrocytomas and oligodendrogliomas

We carried out a population-based study on low-grade diffuse gliomas in the Canton of Zurich, Switzerland (population 1.16 million). From 1980 to 1994, 987 astrocytic and oligodendroglial tumors were diagnosed, of which 122 (12.4%) were low-grade (WHO grade II). The incidence rates adjusted to the World Standard Population, per million population per year, were 2.28 for low-grade diffuse astrocytomas, 0.89 for oligoastrocytomas, and 2.45 for oligodendrogliomas. The survival rate (mean follow-up 7.5+/-4.8 years) was highest for patients with oligodendroglioma (78% at 5 years, 51% at 10 years), followed by those with oligoastrocytoma (70% at 5 years, 49% at 10 years) and fibrillary astrocytoma (65% at 5 years, 31% at 10 years). Survival of patients with gemistocytic astrocytoma was poor, with survival rates of 16% at 5 years and 0% at 10 years. Younger patients (<50 years) survived significantly longer than older patients (>50 years; P=0.013). DNA sequencing, performed in 84% of cases, revealed that TP53 mutations were most frequent in gemistocytic astrocytomas (88%), followed by fibrillary astrocytomas (53%) and oligoastrocytomas (44%), but were infrequent (13%) in oligodendrogliomas. The presence of TP53 mutations was associated with shorter survival of patients with low-grade diffuse gliomas (log-rank test; P=0.047), but when each histological type was analyzed separately, an association was observed only for oligoastrocytoma ( P=0.05). Loss on 1p and 19q were assessed by quantitative microsatellite analysis in 67% of cases. These alterations were frequent in oligodendrogliomas (1p, 57%; 19q, 69%), less common in oligoastrocytomas (1p, 27%; 19q, 45%), rare in fibrillary astrocytomas (1p, 7%; 19q, 7%), and absent in gemistocytic astrocytomas. None of these alterations were predictive of survival. These results establish the frequency of key genetic alterations in low-grade diffuse gliomas at a population-based level. Multivariate Cox's regression analysis indicates that only age and histological type, but not genetic alterations, are significant predictive factors.

Primary malignant brain tumor incidence and Medicaid enrollment

BACKGROUND

The relationship between socioeconomic status and health care disparities in the incidence of brain tumors is unclear.

OBJECTIVE

To identify the associations between age, sex, and Medicaid enrollment and the incidence of primary malignant brain tumors in Michigan in 1996 and 1997.

METHODS

Records were obtained from the Michigan Cancer Surveillance Program on the 1,006 incident cases during this period and cross-checked with Medicaid enrollment files.

RESULTS

Persons enrolled in Medicaid were more likely than non-enrolled persons to develop a malignant brain tumor of any type, a glioblastoma multiforme, and an astrocytoma for certain subgroups. In addition, incidence rates for malignant brain tumors in persons enrolled in Medicaid peaked at a younger age.

CONCLUSION

Sociodemographic status may be associated with cerebral malignancy and should be considered when targeting treatment and educational interventions at persons at risk.

Incidence trends of adult primary intracerebral tumors in four Nordic countries

Brain tumors are some of the most lethal adult cancers and there is a concern that the incidence is increasing. It has been suggested that the reported increased incidence can be explained by improvements in diagnostic procedures, although this has not been totally resolved. The aim of our study was to describe the incidence trends of adult primary intracerebral tumors in four Nordic countries during a period with introduction of new diagnostic procedures and increasing prevalence of mobile phone users. Information about benign and malignant primary intracerebral tumor cases 20-79 years of age was obtained from the national cancer registries in Denmark, Finland, Norway and Sweden for the years 1969-98 and estimates of person-years at risk were calculated from the information obtained from national population registries. Annual age standardized incidence rates per 100,000 person-years were calculated and time trends analyses were carried out using Poisson regression. The overall incidence of all intracerebral tumors ranged from 8.4-11.8 for men and 5.8-9.3 for women, corresponding to an average annual increase of 0.6% for men (95% confidence interval [CI] = 0.4, 0.7) and 0.9% for women (95% CI = 0.7, 1.0). The increase in the incidence was confined to the late 1970s and early 1980s and coinciding with introduction of improved diagnostic methods. This increase was largely confined to the oldest age group. After 1983 and during the period with increasing prevalence of mobile phone users, the incidence has remained relatively stable for both men and women.

Oligodendroglioma and anaplastic oligodendroglioma:

BACKGROUND

Recent advances that have been made in diagnostic imaging, surgical technique, chemotherapy, molecular biology, and prediction of therapeutic response could have potential impact on the optimal diagnosis and treatment of patients with brain tumors, especially those with oligodendrogliomas. In this article, the topic of oligodendroglioma and anaplastic oligodendroglioma is reviewed, highlighting the new clinical developments.

METHODS

Information for this review was obtained by performing a Medline search for recent references using the term "oligodendroglioma." The bibliographies of papers obtained also were checked for articles that could provide additional understanding of this disease and its current treatment.

RESULTS

The incidence of oligodendroglioma is increasing, most likely due to its improved recognition. Seizures and/or headaches are still common presenting features, and surgery continues to be the primary treatment. Positron emission tomography (PET) and molecular analysis of the surgical specimen are emerging as important diagnostic tools. Patients having either oligodendroglioma or anaplastic oligodendroglioma are likely to respond to chemotherapy. This has had an impact upon the timing of radiation therapy. Survival times are increasing, and patients can now be divided into prognostic subgroups based on the molecular features of their tumors. While procarbazine-CCNU-vincristine (PCV) chemotherapy has been the standard, other agents, notably temozolomide, are currently being tested.

CONCLUSIONS

The algorithm for diagnosing and treating patients with oligodendrogliomas has changed. Neurosurgeons need to be aware of the new developments so they can offer sound advice to their patients.

Analysis of a molecular genetic neuro-oncology study with partially biased selection

Oligodendrogliomas are a common variant of malignant brain tumors, and are unique for their relative sensitivity to chemotherapy and better prognosis. For these reasons, the identification of an objective oligodendroglial marker has been a long sought-after goal in the field of neuro-oncology. To this end, 75 patients who received chemotherapy at the London Regional Cancer Centre between 1984 and 1999 were studied (Ino et al., Clinical Cancer Research, 7, 839-845, 2001). Of these 75 patients, 50 were initially treated with chemotherapy (the current practice) and comprise a population-based sample. The remaining 25 patients were initially treated with radiation and were included in the study only because their tumor recurred, at which time they received chemotherapy. Because this group of 25 patients included neither those radiation patients whose tumors never recurred nor those radiation patients whose tumors recurred but were not treated with chemotherapy, issues of selection bias were of concern. For this reason, the initial analysis of these data included only the 50 population-based patients. This was unsatisfying given the rarity of this disease and of genetic information on this disease and led us to question whether we could undertake an analysis that includes all of the patients. Here we examine approaches for utilizing the entire study population, as well as the assumptions required for doing so. We illustrate that there are both costs and benefits to using the 25 selected patients.

Racial differences in the incidence of gliomas: a retrospective study from Memphis, Tennessee

This study records the incidence of glioblastoma multiforme, astrocytoma and oligodendroglioma in the white and Black patients in the Memphis Statistical Metropolitan Area (MSMA) during a 10.5-year period from 1 January 1984 through 30 June 1994. During this time, only six hospitals performed craniotomy and computer tomography (CT) scanning was routine in each of the hospitals. A total of 824 histologically confirmed first diagnoses were made at these six area hospitals. Based on the zip code listed as the home address, we determined patient's locale and identified 373 patients (232 glioblastoma multiforme, 106 astrocytomas and 35 oligodendroglioma) who resided in the area during the study interval. There were 50 black and 323 white patients. The background population for the area was obtained from the US Census Bureau's statistics for the year 1990. These statistics indicated that 40.5% of the population identified themselves as black and 57.9% as white. Age adjusted incidence rates were 1.550 (p < 0.001) for other astrocytomas, and 0.106 and 0.461 (p = 0.003) in the black and white populations, respectively. There was no significant difference in survival between the two populations. This study confirms a significant disparity in incidence rates for the three most common gliomas between the black and white populations and this disparity is higher than predicted by previous reports.

Trends in incidence of primary brain tumors in the United States, 1985-1994

Brain tumor incidence has increased over the last 20 years in all age groups, both overall and for specific histologies. Reasons attributed to these increases include increase in lymphoma due to HIV/AIDS, introduction of computed tomography/magnetic resonance imaging, and changes in coding/classification. The purpose of this study was to describe overall and histologic-specific incidence trends in a population-based series of primary benign and malignant brain tumors. Data from the Central Brain Tumor Registry of the United States from 1985 through 1994 were used to determine incidence trends in the broad age groups 0-19, 20-64, and > or = 65 years, both overall and for selected histologies. Poisson regression was used to express trends as average annual percentage change. Overall, incidence increased modestly (annual percentage change 0.9%, 95% confidence interval, 0.4, 1.4). When lymphomas were excluded, this result was not statistically significant (annual percentage change 0.5%, 95% confidence interval, -0.1, 1.1). Specific histologies that were increasing were lymphomas in individuals aged 20 to 64 years and in males aged 65 years or older, ependymomas in the population aged 20 to 64 years, nerve sheath tumors in males, and pituitary tumors in females. Increases that were not specific to any population subgroup were seen for glioblastoma, oligodendrogliomas, and astrocytomas, excluding not otherwise specified (NOS) tumors. Corresponding decreases were noted for NOS, astrocytoma NOS, and glioma NOS. Increasing incidence trends for lymphomas were consistent with previous literature. Improvements in diagnostic technology in addition to changes in classification and coding were likely to be responsible for decreases seen in incidence of NOS subgroups and corresponding increases in glioma subgroups. In contrast, the increases identified for ependymomas, nerve sheath tumors, and pituitary tumors were less likely to be artifacts of improvements in diagnosis, and they warrant further study.

Lack of association of rare alleles in the HRAS variable number of tandem repeats (VNTR) region with adult glioma

HRAS rare alleles have been associated with the increased susceptibility to a variety of cancers. In the present study we examined the hypothesis that HRAS rare alleles are a risk factor for adult glioma in a population-based case-control study of adult glioma in six San Francisco Bay Area counties. We compared the prevalence of rare alleles in the variable number of tandem repeats region of HRAS in the germline DNA from 73 white adults who had gliomas with that of 65 controls. Overall, the prevalence of rare alleles in cases was not different from the prevalence of those in controls according to two definitions of rare alleles. We found that 25 of 73 (34%) of cases versus 25 of 65 (38%) of controls had at least one allele that was not 30, 46, 69, or 87 repeats; 4 of 73 (5%) of cases versus 6 of 65 (9%) of controls carried one or more alleles with 33, 39, 42, 53, 59, 63, 68, 105, or 114 repeats. The proportion of rare alleles was somewhat higher among subjects with anaplastic astrocytoma. Among women, cases were less likely than controls to have HRAS rare alleles, whereas among men, cases were slightly more likely to have HRAS rare alleles, but none of these results approach statistical significance. Our data do not suggest an excess of HRAS rare alleles among adult glioma cases.

Use of cellular telephones and the risk for brain tumours: A case-control study

The use of cellular telephones has increased dramatically during the 1990's in the world. In the 1980's the analogue NMT system was used whereas the digital GSM system was introduced in early 1990's and is now the preferred system. Case reports of brain tumours in users initiated this case-control study on brain tumours and use of cellular telephones. Also other exposures were assessed. All cases, both males and females, with histopathologically verified brain tumour living in Uppsala-Orebro region (1994-96) and Stockholm region (1995-96) aged 20-80 at the time of diagnosis and alive at start of the study were included, 233 in total. Two controls to each case were selected from the Swedish Population Register matched for sex, age and study region. Exposure was assessed by questionnaires supplemented over the phone. The analyses were based on answers from 209 (90%) cases and 425 (91%) controls. Use of cellular telephone gave odds ratio (OR) = 0.98 with 95% confidence interval (CI) = 0. 69-1.41. For the digital GSM system OR = 0.97, CI = 0.61-1.56 and for the analogue NMT system OR = 0.94, CI = 0.62-1.44 were calculated. Dose-response analysis and using different tumour induction periods gave similar results. Non-significantly increased risk was found for tumour in the temporal or occipital lobe on the same side as a cellular phone had been used, right side OR = 2.45, CI = 0.78-7.76, left side OR = 2.40, CI = 0.52-10.9 Increased risk was found only for use of the NMT system. For GSM use the observation time is still too short for definite conclusions. An increased risk for brain tumour in the anatomical area close to the use of a cellular telephone should be especially studied in the future.

[Oligodendroglioma: a pathological and clinical study of 15 cases]

Oligodendrogliomas account for 4-5% of primary central nervous system tumours with a slow and infiltrative growth. We report the clinical and pathological findings of 15 cases of oligodendrogliomas. Eight patients were males and 7 were females. The ages ranged between 17 and 66 years, with a mean of 39.73 years. The symptoms reflected the growth and topography of the tumours; migraine (60%) and seizures (60%) were the most frequent symptoms. Frontal (n = 6), parietal (n = 2), temporal (n = 1) and occipital (n = 1) lobes were affected. Five patients undergone total resection of the tumor and 10 were submitted to partial resection, from which 3 received adjuvant radiotherapy, 1 adjuvant chemotherapy and 1 chemotherapy and radiotherapy. The overall recurrence rate was 60% for a 32 month follow up. Five recurrences were observed in patients submitted only to the surgical treatment and 4 in which adjuvant radio or chemotherapy were performed. These results are similar with the literature and may contribute to further understanding the biological behavior of these rare tumours.

Proliferation and cell death in oligodendrogliomas

The rates of cell proliferation and of cell loss influence the growth rate of a tumour and reflect genetic changes. We studied proliferation and apoptosis in oligodendrogliomas and their relationship to progression of the tumours. Thirty-two cases of oligodendroglioma were retrieved spanning a 10-year period. The diagnosis and grade were reviewed and follow-up data obtained. Mitotic index (MI) and apoptotic index (AI) were determined from haematoxylin and eosin (H & E) stained sections. A labelling index (LI) of proliferating cells was obtained using the MIB1 antibody to the Ki-67 antigen. A further index of apoptosis was obtained using in situ end-labelling of DNA strand breaks (TUNEL index, TI). Fourteen cases were graded as II, 18 as III (1993 WHO). LI was significantly higher in grade III than in grade II tumours (P < 0.01) but the difference in apoptotic indices between grades was not significant. There was a significant (P = 0.036) positive correlation between the logarithms of TI and LI. Construction of survival curves demonstrated a significant difference in survival according to histological grade (P < 0.05). Stratification of cases by LI alone did not predict significantly different survival outcomes, and apoptotic indices did not demonstrate a relationship to survival. A positive relationship was demonstrated between proliferation and apoptosis in oligodendrogliomas. The levels of apoptosis observed indicate that this phenomenon may have an important influence on the overall rate of tumour growth.

Descriptive epidemiology of cerebral gliomas in France

BACKGROUND

Descriptive epidemiology of cerebral gliomas has recently been the subject of several studies, indicating a possible increase in brain tumor rates, particularly in the elderly population.

METHODS

Between 1983 and 1990, 1376 registered patients with diagnoses of malignant astrocytomas, low grade astrocytomas, oligodendrogliomas - mixed oligoastrocytomas, and tumors without histologic confirmation were reviewed in 6 French cancer registries. The incidence rates by histologic type, age, and gender were calculated. The variation of the incidence between 1983 and 1990 was also analyzed.

RESULTS

The highest incidence was observed in the malignant astrocytoma group (2.38/100,000/year) followed by the low grade astrocytoma group (0.54/100,000/year) and the oligodendroglioma - mixed oligoastrocytoma group (0.25/100,000/year). A significant male predominance was observed in the malignant astrocytoma group (male/female [M/F] ratio of 1.59; P < 0.001) and in the group without histologic confirmation (M/F ratio of 2.6; P = 0.008). Between 1983 and 1990, an increasing trend of 5% per year was observed in the incidence of malignant astrocytomas in the population older than 65 years.

CONCLUSIONS

These data confirm the observation made in other countries that the incidence of primary brain tumors (particularly malignant astrocytomas) is increasing in elderly patients.

Intracranial gliomas in Ferrara, Italy, 1976 to 1991

INTRODUCTION

We planned a descriptive study on the incidence of intracranial gliomas spanning a 16-year period (1976-1991) in the Local Health Service 31 of Ferrara, Northern Italy.

MATERIAL AND METHODS

We used a complete enumeration approach by reviewing all the possible sources of case collection available in the study area.

RESULTS

The mean annual incidence rate was 5.8 new cases per 100,000 population (6.96 for men and 4.78 for women; p < 0.05), resulting in 4.7 per 100,000 when directly adjusted to the Italian population. The age-specific incidences showed a small peak in childhood, an increase with age, reaching a maximum in the age group 60 to 64 and then a decline in the elderly. This pattern is similar for both sexes. The adjusted rates increased from 3.94 per 100,000 population in the first five-year period to 5.6 per 100,000 in the third (a nonsignificant difference). The distribution of cases within the study area was substantially uniform.

CONCLUSION

The incidence rates of Ferrara fell into the middle-high values so far reported and confirmed the male preponderance found in previous studies. The age-related pattern is similar to that observed, with few exceptions, in other surveys. Like other authors we did not find a significant temporal trend, although the incidence rates tended to increase with time. The data encourage further, wider epidemiological studies of a prospective nature.

Good performance status of long-term disease-free survivors of intracranial gliomas

PURPOSE

To determine the long-term impact on function of treatment for primary cerebral gliomas, Karnofsky Performance Status, employment history, and memory function were used to evaluate the status of adults who are alive and disease-free more than 1 year after cranial irradiation.

METHODS AND MATERIALS

Of 30 eligible adult patients, seventeen patients had anaplastic astrocytoma, seven had a glioblastoma, four had low grade astrocytoma, one had a mixed glioma, and one had an anaplastic oligodendroglioma. Sixteen patients received partial brain irradiation only, 12 had whole brain irradiation with a partial brain boost, and two had whole brain irradiation only. The total dose ranged from 54-66 Gy, with a fraction size of 1.7-2.0 Gy. Median follow-up was 3.5 years. Eighty-three percent of patients also received adjuvant chemotherapy.

RESULTS

Karnofsky Performance Status generally remained stable after the completion of irradiation. Mean Performance status was 84 at the end of irradiation and was unchanged at the time of last follow-up. The actuarial freedom from performance status decline after irradiation was 93% at 5 years. The performance status increased in two patients, both within several months of completing irradiation. Most patients (68%) returned to work after irradiation. Sixty-two percent remained at work 1 year later, and 58% were working at the time of last follow-up. No patient who did not return to work within 4 months of completing irradiation was able to work at a later date. All working patients were employed in a capacity similar to their pre-morbid position. Only one patient, with an intercurrent lung cancer, eventually developed deficits that limited self care.

CONCLUSIONS

Contrary to previously published reports, long-term glioma survivors maintained a relatively good performance status in the absence of recurrence and did not experience a progressive decline in neuropsychologic function after completion of cranial irradiation. A patient's function state at the completion of irradiation is a reliable predictor of long-term functional outcome in the absence of recurrence. Although the number of patients in each subgroup is small and no significant differences could be detected, patients treated with partial brain irradiation had a higher and more stable performance status, better memory function, and superior employment history.

Incidence of brain tumours in rats exposed to an aerosol of 239PuO2

Incidence of brain tumours was investigated in 3390 female and male Wistar rats exposed to an aerosol of 239PuO2, or as sham-exposed controls. Lung doses ranged from 0.05 to 22 Gy. In females, six brain tumours were found in 1058 control rats (incidence, 0.6%) and 24 brain tumours in 2134 rats exposed to Pu (incidence, 1.1%); the survival-adjusted level of significance was p = 0.29 for comparing control with exposed females. In males, two brain tumours were found in 60 control rats (incidence, 3.3%) and seven brain tumours in 138 rats exposed to Pu (incidence, 5.1%); the survival-adjusted level of significance was p = 0.33. Brain tumour incidence was about five times greater in male than in female rats (p = 0.0001), demonstrating a highly significant sex difference in brain tumour incidence. Tumour types were distributed similarly among control and Pu-exposed groups of both sexes; most tumours were astrocytomas. Mean lifespans for rats with brain tumours were not significantly different between control and Pu-exposed rats. Plutonium was not detected on autoradiograms of the brain. These results, like those for plutonium workers, show an increase of brain tumours which cannot be demonstrated statistically to be related to radiation exposure.

Age curves of central nervous system tumor incidence in adults: variation of shape by histologic type

Data from nine population-based cancer registries from the National Cancer Institute's Surveillance, Epidemiology, and End Results program of the United States were used to study the incidence of individual histologic types of malignant central nervous system tumors by age and sex among adults. On a log-log scale, incidence increased linearly between the ages 35 and 64, with a slope that was not different between males and females or among registries but that varied by histologic type. The estimated slopes were 0.4 for ependymomas, 1.0 for oligodendrogliomas, 1.7 for astrocytomas, 2.8 for meningiomas, and 3.9 for glioblastomas. The rate at which incidence increased with age was significantly higher for glioblastomas than for other glial tumors. This finding suggests a different mechanism of carcinogenesis for glioblastomas than for other glial tumors.

Oligodendroglioma: incidence and biological behavior in a defined population

The cases of 208 patients with histologically confirmed oligodendrogliomas were studied. The incidence represents 4.2% of all primary brain tumors diagnosed in the Norwegian population over a 25-year period. All of these tumors were cerebral and the majority affected the frontal lobe. The patients' median age at diagnosis was 47 years, with a range from 3 to 76 years; 6% of the oligodendrogliomas occurred in children. The median duration of symptoms before diagnosis was 20.5 months (mean 43 months). Plain skull x-ray films showed calcified deposits in 28% of the tumors. At operation, most of the tumors were poorly defined, without cyst formation, hematoma necrosis, or calcification. The median duration of disease from onset of symptoms until death was 14 months in nine untreated cases. In surgically treated oligodendroglioma patients the median survival time from onset of symptoms was 74 months. The median postoperative survival time was 35 months (mean 52 months). Tumor calcification, as seen on plain skull x-ray films, was associated with a significantly longer survival period. The surgical findings of gross necrosis, gross hypervascularity, and soft tumor consistency were all related to a shorter total duration of disease. Grossly well demarcated lesions were associated with a significantly longer postoperative survival. The length of postoperative survival correlated with the preoperative clinical status. The cumulative proportion of patients surviving 5 years was 0.342. The patient's age and sex did not have a statistically significant influence on survival time. The extent of surgical excision only seemed to play a role when the neurosurgeon considered that he had removed the whole lesion: these patients had a median postoperative survival period 14 months longer than the other oligodendroglioma patients. The ABO blood group of the oligodendroglioma patient was of prognostic value. In particular, patients with blood group A had a distinctly poorer prognosis than patients with O or B blood. The survival data from this unselected series indicate that cerebral oligodendrogliomas have a less favorable prognosis than has generally been believed.

The incidence of naturally-occurring primary brain tumours in the laboratory rat

Histological analysis of 90 spontaneous primary tumours of the brain observed among 8960 ageing rats (Sprague-Dawley-derived) revealed 55 granular-cell meningiomas, 19 neoplastic reticuloses, 11 neuroglial tumours, 4 pineal tumours, and one pleomorphic, meningeal sarcoma. Although all these tumour types can occur in man and other animal species, the high incidence of granular-cell tumours, and the low degree of differentiation of some neuroglial and pineal tumours, appear to be characteristic attributes of the rat.

[Epidemiology of cerebral gliomas]

In the present review the results of the main epidemiologic studies on cerebral gliomas are reported. Various characteristics of patients, i.e. endogenous factors including age, sex, familiarity and constitutional factors, and exogenous factors including perinatal and infectious diseases, trauma and geographic and environmental findings, are considered in turn.

Incidence of primary intracranial neoplasms in an isolated population (the Faroese) during the period 1962-1975

In a retrospective analysis covering a 14-year-period (1962-1975) the annual incidence of primary intracranial neoplasms in an isolated population of about 40,000 (the Faroese) was found to be 9.9 in 100,000. Out of the 52 patients with intracranial neoplasms 20 were alive, while 32 had died when the study was closed on 31st December 1979. Eighteen out of the 34 patients with supratentorial tumours and one patient with acoustic neurinoma had epilepsy.

[Pathology and natural history of mass-lesion in the spinal cord, its covers and in the neighbouring vertebral column (author's transl)]

Space-occupying lesions occurring in the spinal cord, its covers and in the neighbouring vertebral column are reviewed with consideration to their favourite site and the patients age and sex. The main tumor types are described with special reference to the literature and a comparison is made to the findings of specific tumors when occurring intracranially.

Oligodendrogliomas in children

Oligodendrogliomas are quite uncommon in children. In a 41-year period (1935 to 1975) in Connecticut, 12 histologically verified cases of oligodendrogliomas were noted in persons less than 20 years of age, constituting between 1% and 2% of all primary intracranial neoplasms in Connecticut children. Eleven of the neoplasms occurred in the cerebral hemispheres; these cases of cerebral oligodendrogliomas were reviewed and analyzed.

The incidence of spontaneous tumors of the central nervous system of Wistar rats

The brains of 396 old albino rats of the breed Wistar-AF/Han-EMD were examined for spontaneous tumors of the CNS and the following tumors were diagnosed: 1 oligodendroglioma, 1 astrocytoma, 1 mixed glioma, 1 pleomorphic glioma, and 19 meningiomas. Thus the CNS tumor rate was 5.8%. In addition 6 micromeningiomas were found. Knowledge of the spontaneous tumor rate including the tumor incidence in the CNS of the animal strains used for these examinations is a necessary condition for the evaluation of the results of cancerogenicity tests. CNS tumors deserve particular attention because during recent years it was found that certain chemical compounds like for instance N-methyl-N-nitrosourea induce organ-specific tumors in the brain of rats. It is recommended, therefore, to always include the central nervous system in the autopsy and histologic examination of animals from cancerogenicity trials. For cerebral autopsy transversal sections through the different cerebral regions and histologic examination of transversal section surfaces of all tumors and suspected tumor areas are suggested.

[Epidemiological study of primary tumors of the neuraxis in the Rhone-Alps region. Quantitative data on the etiology and geographical distribution of 1670 tumors]

The authors present a retrospective study of 670 histologically verified tumours of the neuraxis collected over 90 months in the Neurological Hospital, Lyons. The main facts concerning histological type, topography of the tumour, date of diagnosis, address, profession, O.B.O. and Rhesus groups, age and sex were codified for feeding into a computer and processed by sophisticated statistical methods. This analysis shows the homogeneity of topographical distribution in the brain of the different types of glioma, the special genetic code of meningiomas (predominance of A and B genes of the A.B.O. group), absence of the same factors for glioblastoma. Sex ratio analysis shows the contrast between definitely masculine tumours--glioblastomas and astrocytomas--and meningiomas and spongioblastomas. Analysis of the "age specific rate" separates tumours prevalent in the young, where incidence is a decreasing function of age (spongioblastoma, medulloblastoma, cerebellar astrocytoma) and tumours prevalent in adults which are mainly meningiomas and glioblastomas whose incidence is an increasing exponential function of age. Epidemiological analysis shows the difference in geographical distribution of glioblastomas and meningiomas. As far as glioblastomas are concerned, it would appear that on to the general rule of constant tumourincidence over the area as a whole, is superimposed another of high incidence in particular districts of the Beaujolais and Maconnais regions. The aetiological implications of these various findings are discussed.