[Epidemiology of primary brain tumor]

Descriptive epidemiology of 30,223 histopathologically confirmed meningiomas in France: 2006-2015

BACKGROUND AND OBJECTIVES

Meningioma is one of the most common neoplasm of the central nervous system. To describe the epidemiology of meningioma operated in France and, to assess grading and histopathological variability among the different neurosurgical centres.

METHODS

We processed the French Brain Tumour Database (FBTDB) to conduct a nationwide population-based study of all histopathologically confirmed meningiomas between 2006 and 2015.

RESULTS

30,223 meningiomas cases were operated on 28,424 patients, in 61 centres. The average number of meningioma operated per year in France was 3,022 (SD ± 122). Meningioma was 3 times more common in women (74.1% vs. 25.9%). The incidence of meningioma increased with age and, mean age at surgery was 58.5 ± 13.9 years. Grade 1, 2, and 3 meningiomas accounted for 83.9%, 13.91% and, 2.19% respectively. There was a significant variability of meningioma grading by institutions, especially for grade 2 which spanned from 5.1% up to 22.4% (p < 0.001). Moreover, the proportion of grade 2 significantly grew over the study period (p < 0.001). There was also a significant variation in grade 1 subtypes diagnosis among the institutions (p < 0.001). 89.05% of the patients had solely one meningioma surgery, 8.52% two and, 2.43% three or more. The number of surgeries was associated to the grade of malignancy (p < 0.001).

CONCLUSION

The incidence of meningioma surgery increased with age and, peaked at 58.5 years. They were predominantly benign with meningothelial subtype being the most common. However, there was a significant variation of grade 1 subtypes diagnosis among the centres involved. The proportion of grade 2 meningioma significantly grew over the study time, on contrary to malignant meningioma proportion, which remained rare and, stable over time around 2%. Likewise, there was a significant variability of grade 2 meningioma rate among the institutions.

Intratumoral heterogeneity in glioblastoma: don't forget the peritumoral brain zone

Glioblastoma (GB) is the most frequent and aggressive primary tumor of the central nervous system. Prognosis remains poor despite ongoing progress. In cases where the gadolinium-enhanced portion of the GB is completely resected, 90% of recurrences occur at the margin of surgical resection in the macroscopically normal peritumoral brain zone (PBZ). Intratumoral heterogeneity in GB is currently a hot topic in neuro-oncology, and the GB PBZ may be involved in this phenomenon. Indeed, this region, which possesses specific properties, has been less studied than the core of the GB tumor. The high rate of local recurrence in the PBZ and the limited success of targeted therapies against GB demonstrate the need for a better understanding of the PBZ. We present here a review of the literature on the GB PBZ, focusing on its radiological, cellular, and molecular characteristics. We discuss how intraoperative analysis of the PBZ is important for the optimization of surgical resection and the development of targeted therapies against GB.

[Stereotactic radiotherapy of intracranial benign tumors]

Stereotactic radiotherapy can be delivered in one fraction or in multiple fractions schedule. It is used in benign tumours such as meningiomas, mainly localized in the base of the skull, for acoustic schwannoma and pituitary tumours. Whatever the tumour, results with the Gamma Knife(®) are the most numerous, but those obtained by linear accelerators, adapted or dedicated, are comparable. The peripheral dose is preferred to the dose delivered to the isocentre. One fraction stereotactic irradiation should be proposed in small lesions and fractionated treatment for tumours larger. Whatever the tumour, the results are satisfactory with a control rate of 90%. However, this value reflects a disparity assessment, radiological stability for meningiomas, radiological stability and preservation of useful hearing in schwannoma and radiological stability and a decrease in hormonal secretions for pituitary adenomas. Overall complication rates are low. In total, the treatment of benign lesions with stereotactic irradiation gives satisfactory results with few complications.

French brain tumor database: 5-year histological results on 25 756 cases

This work aimed to prospectively record all primary central nervous system tumor (PCNST) cases in France, for which histological diagnosis is available. The objectives were to (i) create a national registry and a network to perform epidemiological studies; (ii) implement clinical and basic research protocols; and (iii) harmonize the health care of patients affected by PCNST. For 5 years, 25 756 cases of newly diagnosed and histologically confirmed PCNST have been recorded. Histological diagnoses included glioma (48.9%), all other neuroepithelial tumors (5%), meningioma (28.8%), nerve sheath tumors (8.4%), lymphoma (3.2%) and others (5.7%). Cryopreservation was reported for 6018 PCNST specimens. Tumor resections (R) were performed in 78% cases, while biopsies accounted for 22%. Median age (MA), sex, percentage R and number of cryopreserved tumors were detailed for each histology; for example, out of 6053 glioblastomas (MA 63 years, male 59.4%, R 62%, 1611 were cryopreserved), and out of 37 atypical teratoid/rhabdoid tumors (MA 2 years, male 56.8%, R 94%, 17 were cryopreserved). This database or databank dedicated to PCNST cases contains detailed data on clinical, histological and other characteristics, such as the inclusion of data on cryopreserved specimens that are not available in other European registries. Therefore, this is a valuable resource that can be used for planning future epidemiological and clinical research.

Brain tumors and hormonal factors: review of the epidemiological literature

BACKGROUND

To date, the etiology of primary tumors of the central nervous system (mainly gliomas and meningiomas) is poorly understood. The role of sex hormones has been suggested, based on clinical, experimental, biological, and epidemiological data.

OBJECTIVE

To review the epidemiological studies on the relation between hormonal factors and the occurrence of glioma and meningioma, in order to identify new research developments.

METHODS

Articles published until September 2010 were selected by considering exogenous and endogenous exposures and specific brain tumors. Standardized information was collected from 20 articles: 15 concerning gliomas and 13 meningiomas.

RESULTS

An increased glioma risk was observed with later menarche and menopause, while a reduced glioma risk was observed with hormone replacement therapy (HRT) and oral contraceptive use, despite duration of use had no effect on risk. Meningioma risk increased after menopause and with HRT use. No clear association was found with pregnancy and breastfeeding.

CONCLUSION

Results are globally concordant with the biologic hypothesis assuming that female sex hormones are protective against glioma and may increase the risk of meningioma. However, new epidemiological studies should be conducted in order to confirm these associations and to refine the role of hormonal factors in brain etiology.

Nervous system tumors in adult immigrants to Sweden by subsite and histology

BACKGROUND

The coding of histology of nervous system (NS) tumors with various degrees of malignancies differs between cancer registries, whereby the comparison of incidence rates from one registry to another seems difficult. No study has systematically defined whether the change in the risk of NS tumors upon immigration in adulthood varies by subsite or histology. Therefore, we aimed to address this issue amongst the first-generation immigrants to Sweden based on a large uniform cancer registry data (1958-2006).

METHODS

The nationwide Swedish Family-Cancer Database (2008 version; >11.8 million individuals; 1.8 million immigrants; histology code in force since 1958) was used to calculate standardized incidence ratios (SIRs). We analyzed 28,981 adult cases of NS tumors amongst Swedes and 2519 amongst immigrants (age ≥ 30).

RESULTS

Significantly decreased risks for brain glioma were amongst German (SIR = 0.64), Eastern European (0.62), some Asian (0.71), Chilean (0.34), and African immigrants (0.52). We found an increased risk for brain meningioma amongst Finns (1.15) and former Yugoslavians (1.33), whilst only Norwegians (0.71) and Latin Americans (0.21) had a decreased risk. The risk for spinal ependymoma and astrocytoma was increased in Germans (3.66) and former Yugoslavians (8.89). We found no significant difference for peripheral nerve tumors between immigrants and the native Swedes.

CONCLUSION

Significant differences between risk of NS tumors amongst immigrants and the native Swedes may suggest different risk factor profiles for glioma compared to meningioma indicating a higher etiological role of genetic background or childhood environmental risk factors rather than exposures after immigration.

[Epidemiology of glioblastoma]

An increasing incidence of glioblastoma has been observed over the last 30 years. Improvements in diagnostic tools such as CT scans and MRI, changes observed in histological classifications, and adjustments in neurosurgical practices have contributed substantially to this increase. Moreover, the aging of the population and the increasing occurrence of glioblastoma beyond 60 years of age are additional explanations. In Gironde (France), where a specialized registry has been established, the annual incidence of glioblastoma is 4.96/100,000. Wide geographic variations are observed, possibly linked to ethnicity. However, the role of intrinsic and/or extrinsic factors cannot be ruled out. Comparing data between registries is difficult and requires taking into account periods of recruitment and diagnostic tools. Ethnicity, age, sex, hereditary syndromes, some constitutive polymorphisms, and brain irradiation are the established risk factors Allergies or asthma, certain viral infections, autoimmune diseases, nonsteroidal anti-inflammatory drug intake, substitutive hormonal therapy, and dietary antioxidant intake are the established protective factors. Many studies on electromagnetic fields - in particular cellular phones - pesticides, solvents, and other factors have been published. Until now, the results are discordant or are not confirmed because of methodological limitations. Future studies combining constitutive polymorphisms and exposure assessment are likely to provide consistent and important data that will improve our knowledge in the epidemiology of glioblastoma.