Immune-related conditions and subsequent risk of brain cancer in a cohort of 4.5 million male US veterans

AllergoOncology: Biomarkers and refined classification for research in the allergy and glioma nexus-A joint EAACI-EANO position paper

Epidemiological studies have explored the relationship between allergic diseases and cancer risk or prognosis in AllergoOncology. Some studies suggest an inverse association, but uncertainties remain, including in IgE-mediated diseases and glioma. Allergic disease stems from a Th2-biased immune response to allergens in predisposed atopic individuals. Allergic disorders vary in phenotype, genotype and endotype, affecting their pathophysiology. Beyond clinical manifestation and commonly used clinical markers, there is ongoing research to identify novel biomarkers for allergy diagnosis, monitoring, severity assessment and treatment. Gliomas, the most common and diverse brain tumours, have in parallel undergone changes in classification over time, with specific molecular biomarkers defining glioma subtypes. Gliomas exhibit a complex tumour-immune interphase and distinct immune microenvironment features. Immunotherapy and targeted therapy hold promise for primary brain tumour treatment, but require more specific and effective approaches. Animal studies indicate allergic airway inflammation may delay glioma progression. This collaborative European Academy of Allergy and Clinical Immunology (EAACI) and European Association of Neuro-Oncology (EANO) Position Paper summarizes recent advances and emerging biomarkers for refined allergy and adult-type diffuse glioma classification to inform future epidemiological and clinical studies. Future research is needed to enhance our understanding of immune-glioma interactions to ultimately improve patient prognosis and survival.

Maternal and childhood medical history and the risk of childhood brain tumours: a case-control study in Ontario, Canada

BACKGROUND

Studies to date have yielded inconclusive results as to whether maternal medical history during pregnancy, and a child's early-life medical history contribute to the development of childhood brain tumours (CBTs). This study examined associations between maternal and childhood medical history and the risk of CBTs.

METHODS

The Childhood Brain Tumour Epidemiology Study of Ontario (CBREO) examined children 0-15 years of age with newly diagnosed CBTs from 1997 to 2003. Multivariable logistic regression analysis determined associations for prenatal medications and childhood medical history, adjusted for child's demographics, and maternal education. Analyses were stratified by histology. A latency period analysis was conducted using 12- and 24-month lead times.

RESULTS

Maternal intake of immunosuppressants during the prenatal period was significantly associated with glial tumours (OR 2.73, 95% CI 1.17-6.39). Childhood intake of anti-epileptics was significantly associated with CBTs overall, after accounting for 12-month (OR 8.51, 95% CI 3.35-21.63) and 24-month (OR 6.04, 95% CI 2.06-17.70) lead time before diagnosis. No associations for other medications were found.

CONCLUSIONS

This study underscores the need to examine potential carcinogenic effects of the medication classes highlighted and of the indication of medication use. Despite possible reverse causality, increased CBT surveillance for children with epilepsy might be warranted.

Disease burden, risk factors, and trends of primary central nervous system (CNS) cancer: A global study of registries data

BACKGROUND

This study aimed to evaluate the global incidence, mortality, associated risk factors, and temporal trends of central nervous system (CNS) cancer by sex, age, and country.

METHODS

We extracted incidence and mortality of CNS cancer from the GLOBOCAN (2020), Cancer Incidence in Five Continents series I-X, WHO mortality database, the Nordic Cancer Registries, and the Surveillance, Epidemiology, and End Results Program. We searched the Global Health data exchanges for the prevalence of its associated risk factors. We tested the trends by Average Annual Percentage Change (AAPC) from Joinpoint regression analysis with 95% confidence intervals in different age groups.

RESULTS

The age-standardized rates (ASRs) of CNS cancer incidence and mortality were 3.5 and 2.8 per 100,000 globally. Southern Europe (ASR = 6.0) and Western Asia (ASR = 4.2) had the highest incidence and mortality, respectively. The incidence was associated with Human Development Index, Gross Domestics Products per capita, prevalence of traumatic brain injuries, occupational carcinogens exposure, and mobile phone use at the country level. There was an overall stable and mixed trend in the CNS cancer burden. However, increasing incidence was observed in younger male population from five countries, with Slovakia (AAPC = 5.40; 95% CI 1.88, 9.04; P = .007) reporting the largest increase.

CONCLUSIONS

While the overall global trends of cancer have been largely stable, significant increasing trends were found in the younger male population. The presence of some higher-HDI countries with increasing mortality suggested an ample scope for further research and exploration of the reasons behind these epidemiological trends.

Trends in Intracranial Glioma Incidence and Mortality in the United States, 1975-2018

Purpose

Glioma incidence in the US seems to have stabilized over the past 20 years. It’s also not clear whether changes in glioblastoma incidence are associated with glioma mortality trends. Our study investigated trends in glioma incidence and mortality according to tumor characteristics.

Methods

This study obtained data from the Surveillance, Epidemiology, and End Results-9 (SEER-9) registries to calculate glioma incidence and mortality trends. Annual percent changes (APC) and 95% CIs were calculated using the Joinpoint program.

Results

62,159 patients (34,996 males and 55,424 whites) were diagnosed with glioma during 1975-2018, and 31,922 deaths occurred from 1995-2018. Glioblastoma (32,893 cases) and non-glioblastoma astrocytoma (17,406 cases) were the most common histologic types. During the study period, the incidence of glioma first experienced a significant increase (APC=1.8%, [95% CI, 1.3% to 2.3%]) from 1975 to 1987, and then experienced a slight decrease (APC=-0.4%, [95% CI, -0.5% to -0.3%]) from 1987 to 2018, while the APC was 0.8% for glioblastoma, -2.0% for non-glioblastoma astrocytoma, 1.1% for oligodendroglial tumors, 0.7% for ependymoma and -0.3% for glioma NOS during the study period. Glioblastoma incidence increased for all tumor size and tumor extension except for distant. From 1995 to 2018, glioma mortality declined 0.4% per year (95% CI: -0.6% to -0.2%) but only increased in patients older than 80 years [APC=1.0%, (95% CI, 0.4% to 1.6%)].

Conclusion

Significant decline in glioma incidence (1987-2018) and mortality (1995-2018) were observed. Epidemiological changes in non-glioblastoma astrocytoma contributed the most to overall trends in glioma incidence and mortality. These findings can improve understanding of risk factors and guide the focus of glioma therapy.

Targeting Immune Modulators in Glioma While Avoiding Autoimmune Conditions

Communication signals and signaling pathways are often studied in different physiological systems. However, it has become abundantly clear that the immune system is not self-regulated, but functions in close association with the nervous system. The neural-immune interface is complex; its balance determines cancer progression, as well as autoimmune disorders. Immunotherapy remains a promising approach in the context of glioblastoma multiforme (GBM). The primary obstacle to finding effective therapies is the potent immunosuppression induced by GBM. Anti-inflammatory cytokines, induction of regulatory T cells, and the expression of immune checkpoint molecules are the key mediators for immunosuppression in the tumor microenvironment. Immune checkpoint molecules are ligand-receptor pairs that exert inhibitory or stimulatory effects on immune responses. In the past decade, they have been extensively studied in preclinical and clinical trials in diseases such as cancer or autoimmune diseases in which the immune system has failed to maintain homeostasis. In this review, we will discuss promising immune-modulatory targets that are in the focus of current clinical research in glioblastoma, but are also in the precarious position of potentially becoming starting points for the development of autoimmune diseases like multiple sclerosis.

Prospective investigation of polyomavirus infection and the risk of adult glioma

Glioma is an aggressive primary tumor of the brain with a poorly understood etiology. We studied the association of 4 human polyomaviruses (HPyV)—JC virus (JCV), BK virus (BKV), human polyomavirus 6 (HPyV6), and Merkel cell polyomavirus (MCPyV) with glioma risk within the Cancer Prevention Study II in the US (CPS-II) and the Janus Serum Bank in Norway. Cohort participants subsequently diagnosed with glioma from the CPS-II (n = 37) and Janus Serum Bank (n = 323), a median of 6.9 and 15.4 years after blood collection, respectively, were matched to individual controls on age, sex, and date of blood draw. Serum antibodies to the major viral capsid protein (VP1) were used to establish infection history for each polyomavirus. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. In the Janus Serum Bank, MCPyV infection was associated with a higher risk of glioma overall (OR: 1.56; 95% CI 1.10, 2.19). A modest, nonsignificant positive association with MCPyV infection was also observed in CPS-II (OR: 1.29; 95% CI 0.54, 3.08). In both cohorts, glioma risk was not significantly related to infection with JCV, BKV or HPyV6. The present study suggests that MCPyV infection may increase glioma risk.

Increased Malignancy Rate in Children With IgE Deficiency: A Single-center Experience

BACKGROUND

Immunoglobulin (Ig) E-deficient adults (IgE<2.5 kU/L) have increased susceptibility for developing malignancy. We evaluated the association between IgE deficiency and cancer diagnosis in children (age younger than 18 y), compared with those non-IgE-deficient (IgE≥2.5 kU/L).

MATERIALS AND METHODS

Information about malignancy diagnosis were compared between 4 cohorts of children who had IgE levels measured at our institution: IgE-deficient (IgE<2.5 kU/L), normal IgE (2.5

RESULTS

Overall, 94/4586 (2%) children had IgE deficiency. A significantly higher malignancy rate was found in IgE-deficient children (3/94, 3.2%) compared with non-IgE-deficient cohort (13/4492, 0.3%, P<0.0001). Analysis of the groups with different IgE levels revealed a significantly higher rate of cancer in IgE-deficient children (3.2%) compared with those with normal (0.5%; odds ratio [OR]=7.84; 95% confidence interval [CI]: 1.94-31.61, P=0.004), high (0.2%; OR=25.80; 95% CI: 4.94-134.54, P=0.002), and very high IgE levels (0.2%; OR=42.17; 95% CI: 3.84-463.02, P<0.0001). All 3 IgE-deficient children had lymphoma. Malignancies in the other groups included lymphoma, leukemia, brain, liver, ovarian cancers.

CONCLUSIONS

Malignancy rate was higher in IgE-deficient children compared with those with normal, high, or very high IgE levels, supporting the hypothesis that IgE deficiency may be a marker for malignancy susceptibility in children. Larger, prospective studies are necessary to further evaluate this association.

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MESH Headings

• Child
• Child, Preschool
• Female
• Humans
• Immunoglobulin E/blood
• Immunoglobulin E/deficiency
• Male
• Neoplasms/blood
• Neoplasms/diagnosis
• Neoplasms/etiology
• Odds Ratio
• Prospective Studies
• Risk Factors

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Affiliation(s)

Denisa Ferastraoaru Department of Internal Medicine/Allergy-Immunology, Albert Einstein College of Medicine/Montefiore Medical Center
Deborah Schwartz Albert Einstein College of Medicine, Bronx, NY
David Rosenstreich Department of Internal Medicine/Allergy-Immunology, Albert Einstein College of Medicine/Montefiore Medical Center

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The effects of chitosan-based materials on glioma: Recent advances in its applications for diagnosis and treatment

Glioma is known as the most common primary brain tumor occurring in adolescents and is considered as a lethal disease worldwide. Despite the advancements in presently available therapeutic approaches (i.e. radiation therapy and chemotherapy), the rate of amelioration in glioma patients is still low. In this regard, it seems that there is a need for reconsidering and enhancing current therapies and/or discovering novel therapeutic platforms. Chitosan is a natural polysaccharide with several beneficial characteristics, including biocompatibility, biodegradability, and low toxicity. Without causing toxic effects on healthy cells, chitosan nanoparticles are attractive targets in cancer therapy which lead to the sustained release and enhanced internalization of chemotherapeutic drugs as well as higher cytotoxicity for cancer cells. Hence, these properties turn it into a suitable candidate for the treatment of various cancers, including glioma. In the viewpoint of glioma, cancer inhibition is possible through targeting glioma-associated signaling pathways and molecules such as MMP-9, VEGF, TRAIL and nuclear factor-κB by chitosan and its derivatives. Moreover, it has been acknowledged that chitosan and its derivatives can be applied as a delivery system for carrying a diverse range of therapeutic agents to the tumor site. Besides the anti-glioma effects of chitosan and its derivatives, these molecules can be utilized for culturing glioma cancer cells; providing a better understanding of glioma pathogenesis. Furthermore, it is documented that 3D chitosan scaffolds are potential targets that offer advantageous drug screening platforms. Herein, we summarized the anti-glioma effects of chitosan and also its utilization as drug delivery systems in the treatment of glioma.

Descriptive Epidemiology of Brain and Central Nervous System Tumours: Results from Iran National Cancer Registry, 2010-2014

Background

Central nervous system (CNS) tumours account for only 1-2% of cancer incidence but are a major reason for mortality and morbidity due to malignancies. Recent studies show an increase in the rate of CNS tumours worldwide, especially in developing countries. Moreover, there is significant heterogeneity in epidemiological patterns worldwide. This study is aimed at representing nationwide epidemiology of CNS tumours in Iran.

Methods

Iran National Cancer Registry 2010-2014 data were reviewed for CNS tumours. The epidemiological rates were calculated for both genders and all age groups using the 2011 census information.

Results

Out of 17345 cases, 58.5% were men and 41.5% were women. The mean age was 45.55 years ranging from less than 1 month to 100 years old. Average total age-standardized incidence rate (ASR) was 5.19 for primary tumours. The annual percent change (APC) was 14.23% during the study period. The most frequent site and histology recorded were brain, NOS and diffuse astrocytic, respectively. Geographical distribution showed about five-fold difference in ASRs between different provinces.

Conclusion

The overall ASR calculated was higher than the global rate in 2012 but lower than that of most developed countries, showing an increasing trend which may be due to either advances in diagnosing or risk factor augmentation. The mean age and incident rates were higher than those of previous reports in Iran.

AllergoOncology: ultra-low IgE, a potential novel biomarker in cancer-a Position Paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Elevated serum IgE levels are associated with allergic disorders, parasitosis and specific immunologic abnormalities. In addition, epidemiological and mechanistic evidence indicates an association between IgE-mediated immune surveillance and protection from tumour growth. Intriguingly, recent studies reveal a correlation between IgE deficiency and increased malignancy risk. This is the first review discussing IgE levels and links to pathological conditions, with special focus on the potential clinical significance of ultra-low serum IgE levels and risk of malignancy. In this Position Paper we discuss: (a) the utility of measuring total IgE levels in the management of allergies, parasitosis, and immunodeficiencies, (b) factors that may influence serum IgE levels, (c) IgE as a marker of different disorders, and d) the relationship between ultra-low IgE levels and malignancy susceptibility. While elevated serum IgE is generally associated with allergic/atopic conditions, very low or absent IgE may hamper anti-tumour surveillance, indicating the importance of a balanced IgE-mediated immune function. Ultra-low IgE may prove to be an unexpected biomarker for cancer risk. Nevertheless, given the early stage of investigations conducted mostly in patients with diseases that influence IgE levels, in-depth mechanistic studies and stratification of malignancy risk based on associated demographic, immunological and clinical co-factors are warranted.

Autoimmune diseases and immunosuppressive therapy in relation to the risk of glioma

Effectors from the immune system can modulate the course and possibly the early development of gliomas. We, therefore, hypothesized that autoimmune diseases associated with increased immune‐surveillance may also modulate the risk of human glioma. To test this hypothesis, we used data from the well‐validated Clinical Practice Research Datalink (CPRD) GOLD from the UK to analyze the association of immune‐related disorders or use of immunosuppressive drugs and the risk of glioma. We identified 3112 incident glioma cases diagnosed between 1995 and 2017. We randomly selected up to 10 controls, matching them to glioma cases on age, sex, index date, general practice, and number of years of active history in the database prior to the index date. We performed conditional logistic regression analyses to estimate Odds Ratios (ORs) of glioma among those exposed to allergies, autoimmune diseases, and immunosuppressive drugs. Overall, we found no materially altered association between a history of any autoimmune disease (OR 0.98, 95% CI 0.86‐1.11), allergy (OR 0.97, 95% CI 0.89‐1.05), or use of immunosuppressive drugs and the risk of glioma. However, subgroup analyses among younger patients found a statistically significant increased risk of glioma in patients with a history of inflammatory bowel disease (IBD) (OR 2.59, 95% CI 1.31‐5.12). There was also an inverse association between asthma and risk of glioma in patients with longer survival (OR 0.73, 95% CI 0.58‐0.91) and between long‐term duration diabetes and risk of glioma (OR 0.71, 95% CI 0.53‐0.96).

Asthma and risk of glioma: a population-based case-control study

OBJECTIVES

Literature suggests an inconsistent, but largely inverse, association between asthma and risk of glioma, which is primarily due to methodological inconsistency in sampling frame and ascertainment of asthma. The objective of the study was to clarify the association between asthma and risk of glioma by minimising methodological biases (eg, recall and detection bias).

DESIGN

A population-based case-control study.

SETTING

General population in Olmsted County, Minnesota, USA.

PARTICIPANTS

All eligible biopsy-proven incident glioma cases (1995-2014) and two sets of controls among residents matched to age and sex (first set: community controls without glioma; second set: MRI-negative controls from the same community).

METHODS

The predetermined asthma criteria via medical record review were applied to ascertain asthma status of cases and controls. History of asthma prior to index date was compared between glioma cases and their matched controls using conditional logistic regression models. Propensity score for asthma status was adjusted for multivariate analysis.

RESULTS

We enrolled 135 glioma cases (median age at index date: 53 years) and 270 controls. Of the cases, 21 had a history of asthma (16%), compared with 36 of MRI controls (27%) (OR (95% CI) 0.48 (0.26 to 0.91), p=0.03). With MRI controls, an inverse association between asthma and risk of glioma persisted after adjusting for the propensity score for asthma status, but did not reach statistical significance probably due to the lack of statistical power (OR (95% CI) 0.48 (0.21 to 1.09); p=0.08). Based on comparison of characteristics of controls and cases, community controls seem to be more susceptible to a detection bias.

CONCLUSIONS

While differential detection might account for the association between asthma and risk of glioma, asthma may potentially pose a protective effect on risk of glioma. Our study results need to be replicated by a larger study.

A new look at IgE beyond allergies

Immunoglobulin E (IgE), though constitutively present at low levels, is most commonly studied in atopic disease where it plays a vital role in mast cell degranulation and in initiating a T helper 2 (Th2) response. With the advent of better detection assays, however, researchers are discovering the importance of IgE in actively contributing to many disease states and pathologies. This review will discuss the latest findings in IgE beyond its role in allergies and recently discovered roles for IgE in its cell-bound form on FcεRI-expressing effector cells like monocytes and dendritic cells. In terms of parasites, we will discuss helminth-induced IgE that appears to protect the worms from immune recognition and a tick-borne illness that elicits an IgE response against red meat. Next, we describe recent findings of how auto-reactive IgE can contribute to the progression of lupus and induce organ damage. Finally, we summarize the emerging roles of IgE in tumor surveillance and antibody-dependent cytotoxicity. We additionally discuss recent or ongoing clinical trials that either target harmful IgE or use the unique characteristics of the isotype.

Allergic Signs in Glioma Pathology: Current Knowledge and Future Perspectives

Historically restrained to immune defense against parasite infections, allergic inflammation has been recently rediscovered to protect from a wide array of environmental triggers, such as xenobiotics and carcinogens, which can induce DNA damage and ultimately lead to cancer development. Moreover, cells and mediators typical of allergic responses can importantly modulate the tissue inflammatory milieu, which represents a crucial gatekeeper towards the acquisition of malignancy by cancer cells through immune escape. Numerous studies have described an inverse association between allergies and glioma development. Mast cells, key players of allergic reactions, have been recently found at increased numbers in glioblastoma multiforme (GBM), the most common and lethal primary brain tumor, and they have been implicated in GBM pathogenesis. In this review, we summarize epidemiological studies and discuss the main evidence highlighting a potential interplay between allergic responses, and glioma formation and progression. Last, we draw future lines of research for better clarification whether and through which mechanisms allergic inflammation might impact on gliomagenesis. The comprehension of the immune mechanisms favoring or counteracting tumor growth might open the path to novel immunotherapy approaches.

Does diabetes decrease the risk of glioma? A systematic review and meta-analysis of observational studies

PURPOSE

Increasing epidemiologic evidence suggests that diabetes mellitus (DM) may be associated with a decreased risk of glioma. This systematic review assessed whether DM was associated with glioma risk.

METHODS

Electronic searches were performed in PubMed, Web of Science, EMBASE, and Cochrane Library databases up to August 30, 2018. A random-effects model was performed to calculate summary effect size with corresponding 95% confidence intervals (CIs).

RESULTS

In total, 10 studies (eight case-control studies and two cohort studies) matched the inclusion criteria. Meta-analyses of case-control studies showed that DM decreased the risk of glioma by 23% (odds ratio: 0.77, 95% CI: 0.61-0.96; P = .02, I² = 82.0%). However, no such effect was observed in cohort studies (relative risk: 0.71, 95% CI: 0.10-4.80; P = .72, I² = 61.6%). In the subgroup analyses, DM was associated with a decreased risk of glioma in Caucasians but not in Asians; the inverse association was slightly higher in males than in females.

CONCLUSIONS

Our results indicate that DM decreases the risk of glioma, but the inverse association may vary in subgroups. The present conclusions should be confirmed with further studies.

Serially measured pre-diagnostic levels of serum cytokines and risk of brain cancer in active component military personnel

Background

There is growing evidence that history of allergic or autoimmune disease is associated with reduced risk of glioma, but few prospective studies have explored the biological basis. To assess associations with immune conditions and levels of 14 cytokines in serial prediagnostic serum samples, we conducted a study of glioma/brain cancer nested in a cohort of active component military personnel.

Methods

A total of 457 case-control sets were ascertained from the Department of Defense (DoD) Automated Central Tumour Registry, Defense Medical Surveillance System (DMSS) database, and DoD Serum Repository. These were individually matched on sex, race/ethnicity, birth year, number of serum samples (1, 2 or 3), and date(s) of sample collection. We obtained diagnoses of pre-existing immune-related conditions from the DMSS database and measured cytokines using Meso Scale Discovery assays. Statistical analyses included conditional logistic regression.

Results

Overall association between glioma and prior immune-related conditions was null. Higher levels of IL-15 and IL-16 were independently associated with lower glioma risks (P_trend = 0.002 and P_trend = 0.001); both associations were more pronounced in individuals with prior immune conditions (P_{heterogeneity} = 0.0009 and P_{heterogeneity} = 0.031).

Conclusions

Associations with pre-diagnostic levels of IL-15 and IL-16 and their modification by diagnosis of immune-related conditions support the importance of immune alterations in glioma aetiology years before diagnosis.

AllergoOncology - the impact of allergy in oncology: EAACI position paper

Th2 immunity and allergic immune surveillance play critical roles in host responses to pathogens, parasites and allergens. Numerous studies have reported significant links between Th2 responses and cancer, including insights into the functions of IgE antibodies and associated effector cells in both antitumour immune surveillance and therapy. The interdisciplinary field of AllergoOncology was given Task Force status by the European Academy of Allergy and Clinical Immunology in 2014. Affiliated expert groups focus on the interface between allergic responses and cancer, applied to immune surveillance, immunomodulation and the functions of IgE-mediated immune responses against cancer, to derive novel insights into more effective treatments. Coincident with rapid expansion in clinical application of cancer immunotherapies, here we review the current state-of-the-art and future translational opportunities, as well as challenges in this relatively new field. Recent developments include improved understanding of Th2 antibodies, intratumoral innate allergy effector cells and mediators, IgE-mediated tumour antigen cross-presentation by dendritic cells, as well as immunotherapeutic strategies such as vaccines and recombinant antibodies, and finally, the management of allergy in daily clinical oncology. Shedding light on the crosstalk between allergic response and cancer is paving the way for new avenues of treatment.

Associations between prediagnostic blood glucose levels, diabetes, and glioma

Previous literature indicates that pre-diagnostic diabetes and blood glucose levels are inversely related to glioma risk. To replicate these findings and determine whether they could be attributed to excess glucose consumption by the preclinical tumour, we used data from the Apolipoprotein MOrtality RISk (AMORIS) (n = 528,580) and the Metabolic syndrome and Cancer project (Me-Can) cohorts (n = 269,365). We identified individuals who were followed for a maximum of 15 years after their first blood glucose test until glioma diagnosis, death, emigration or the end of follow-up. Hazard ratios (HRs), 95% confidence intervals (CIs) and their interactions with time were estimated using Cox time-dependent regression. As expected, pre-diagnostic blood glucose levels were inversely related to glioma risk (AMORIS, P_trend = 0.002; Me-Can, P_trend = 0.04) and pre-diagnostic diabetes (AMORIS, HR = 0.30, 95% CI 0.17 to 0.53). During the year before diagnosis, blood glucose was inversely associated with glioma in the AMORIS (HR = 0.78, 95% CI 0.66 to 0.93) but not the Me-Can cohort (HR = 0.99, 95% CI 0.63 to 1.56). This AMORIS result is consistent with our hypothesis that excess glucose consumption by the preclinical tumour accounts for the inverse association between blood glucose and glioma. We discuss additional hypothetical mechanisms that may explain our paradoxical findings.

Study designs may influence results: the problems with questionnaire-based case-control studies on the epidemiology of glioma

Glioma is a rare brain tumour with a very poor prognosis and the search for modifiable factors is intense. We reviewed the literature concerning risk factors for glioma obtained in case-control designed epidemiological studies in order to discuss the influence of this methodology on the observed results. When reviewing the association between three exposures, medical radiation, exogenous hormone use and allergy, we critically appraised the evidence from both case-control and cohort studies. For medical radiation and hormone replacement therapy (HRT), questionnaire-based case-control studies appeared to show an inverse association, whereas nested case-control and cohort studies showed no association. For allergies, the inverse association was observed irrespective of study design. We recommend that the questionnaire-based case-control design be placed lower in the hierarchy of studies for establishing cause-and-effect for diseases such as glioma. We suggest that a state-of-the-art case-control study should, as a minimum, be accompanied by extensive validation of the exposure assessment methods and the representativeness of the study sample with regard to the exposures of interest. Otherwise, such studies cannot be regarded as 'hypothesis testing' but only 'hypothesis generating'. We consider that this holds true for all questionnaire-based case-control studies on cancer and other chronic diseases, although perhaps not to the same extent for each exposure-outcome combination.

Cancers of the brain and CNS: global patterns and trends in incidence

Background

Cancers of the brain and CNS constitute a group of rare and heterogeneous tumors. Increasing incidence in Western populations has been linked to improvements in diagnostic technology, although interpretation is hampered by changes in diagnosis and reporting. The present study examines geographic and temporal variations in incidence rates of brain and CNS cancers worldwide.

Methods

Data from successive volumes of Cancer Incidence in Five Continents were used, including 96 registries in 39 countries. We used Joinpoint regression to estimate the average annual percentage change and its 95% CI.

Results

Globally, a large variability in the magnitude of the diagnosis of new cases of brain and CNS cancer was found, with a 5-fold difference between the highest rates (mainly in Europe) and the lowest (mainly in Asia). Increasing rates of brain and CNS cancer were found in South America, namely in Ecuador, Brazil, and Colombia; in eastern Europe (Czech Republic and Russia), in southern Europe (Slovenia), and in the 3 Baltic countries. Trends were similar between sexes, although decreasing trends in men and women were seen in Japan and New Zealand.

Conclusions

Important regional variations in brain and CNS cancers exist, and given an increasing burden and risk worldwide, there is a need for further etiological research that focuses on the elucidation of environmental risk. The trends are sufficiently complex and diffuse, however, to warrant a cautious approach to interpretation.

Diabetes mellitus and the risk of glioma: a meta-analysis

Some studies reported a statistically significant inverse association between diabetes mellitus (DM) and risk of gliomas. However, the result is still controversial. We thus did a meta-analysis and summarized the evidence on the incidence of gliomas that has been studied in its association with DM. Seven case-control studies and 4 cohort studies were selected in this meta-analysis (n = 5898251). DM was significantly associated with decreased risk of gliomas (OR = 0.79; 95% CI 0.67 – 0.93; P = 0.004; I² = 59%). In the subgroup analysis of race, Caucasians of DM showed decreased risk of gliomas (OR = 0.81; 95% CI 0.69 – 0.94; P = 0.007). In the subgroup analysis of design, a statistically significant protective effect of DM on gliomas was observed in case-control studies (OR = 0.68; 95 % CI, 0.53–0.87; P = 0.002), while no such effect was observed in cohort studies (OR = 0.97; 95 % CI, 0.83–1.13; P = 0.70). In a further stratified analysis by gender, a significant association was found among males with DM (OR = 0.83; 95 % CI, 0.70–0.99; P = 0.04). No significant association was found between females with DM and gliomas (OR = 0.97; 95 % CI, 0.78–1.21; P = 0.81). In summary, this meta-analysis of current evidence suggests that DM is significantly associated with decreased gliomas risk in Caucasian and males.

Epidemiology

More than 250,000 new cases of primary malignant brain tumors are diagnosed annually worldwide, 77% of which are gliomas. A small proportion of gliomas are caused by the inheritance of rare high-penetrance genetic variants or high-dose radiation. Since 2009, inherited genetic variants in 10 regions near eight different genes have been consistently associated with glioma risk via genome-wide association studies. Most of these variants increase glioma risk by 20-40%, but two have higher relative risks. One on chromosome 8 increases risk of IDH-mutated gliomas sixfold and another that affects TP53 function confers a 2.5-fold increased risk of glioma. Functions of some of the other risk variants are known or suspected, but future research will determine functions of other risk loci. Recent progress also has been made in defining subgroups of glioma based on acquired alterations within tumors. Allergy history has been consistently associated with reduced glioma risk, though the mechanisms have not yet been clarified. Future studies will need to be large enough so that environmental and constitutive genetic risk factors can be examined within molecularly defined, etiologically homogeneous subgroups.

Diabetes, use of antidiabetic drugs, and the risk of glioma

BACKGROUND

Prior epidemiologic studies suggest inverse relations between diabetes and glioma risk, but the underlying mechanisms, including use of antidiabetic drugs, are unknown.

METHODS

We therefore performed a matched case-control analysis using the Clinical Practice Research Datalink (CPRD). We identified incident glioma cases diagnosed between 1995 and 2012 and matched each case with 10 controls on age, gender, calendar time, general practice, and years of active history in the CPRD. We performed conditional logistic regression to estimate odds ratios (ORs) with 95% CIs, adjusted for body mass index and smoking.

RESULTS

We identified 2005 cases and 20 050 controls. Diabetes was associated with decreased risk of glioma (OR = 0.74; 95% CI = 0.60-0.93), particularly glioblastoma (OR = 0.69; 95% CI = 0.51-0.94). Glioblastoma risk reduction was markedly pronounced among diabetic men (OR = 0.60; 95% CI = 0.40-0.90), most apparently for those with diabetes of long-term duration (OR for >5 vs 0 y = 0.46; 95% CI = 0.26-0.82) or poor glycemic control (OR for HbA1c ≥ 8 vs <6.5% = 0.20; 95% CI = 0.06-0.70). In contrast, the effect of diabetes on glioblastoma risk was absent among women (OR = 0.85; 95% CI = 0.53-1.36). No significant associations with glioma were found for use of metformin (OR for ≥ 30 vs 0 prescriptions = 0.72; 95% CI = 0.38-1.39), sulfonylureas (OR = 0.71; 95% CI = 0.39-1.30), or insulin (OR = 0.79; 95% CI = 0.37-1.69).

CONCLUSIONS

Antidiabetic treatment appears to be unrelated to glioma, but long-term diabetes duration and increased HbA1c both show decreased glioma risk. Stronger findings in men than women suggest low androgen levels concurrent with diabetes as a biologic mechanism.

A pooled multisite analysis of the effects of atopic medical conditions in glioma risk in different ethnic groups

PURPOSE

The incidences of atopic conditions (allergies, asthma, or eczema) and glioma vary by ethnicity. Atopic conditions are inversely associated with gliomas. We conducted a pooled multisite study investigating the associations of atopic conditions with glioma in different race/ethnicity groups.

METHODS

Using glioma cases and healthy controls, unconditional logistic regression was conducted to assess the associations of atopic conditions with glioma separately in white, black, Asian, and Hispanic subpopulations. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

Glioblastoma multiforme cases were less likely than controls to report a history of atopic conditions in whites (OR = 0.46, [95% CI, 0.38-0.54]) and Asians (OR = 0.27, [95% CI, 0.10-0.73]). The same trend was seen when looking at glioma cases of all histologies. An inverse association was not seen in blacks for glioblastoma multiforme or all histologies combined.

CONCLUSIONS

The inverse association between glioma and atopic conditions may vary by ethnicity due to a difference in the biology of atopic conditions in different ethnicities but may be due to chance because of the limitations of small nonwhite sample sizes.

Statin use and survival following glioblastoma multiforme

AIM

While some studies indicate a potential chemopreventive effect of statin use on the risk of glioma, the effect of statins on the prognosis of brain tumours has not yet been examined. We thus conducted a cohort study evaluating the influence of statin use on survival in patients with glioblastoma multiforme (GBM).

METHODS

We identified 1562 patients diagnosed with GBM during 2000-2009 from the Danish Cancer Registry and linked this cohort to Danish nationwide demographic and health registries. Within the GBM cohort, each patient recorded as using statins prior to diagnosis (defined as ≥ 2 redeemed prescriptions) was matched to two statin non-users (<2 redeemed prescriptions) by propensity scores based on age, gender, year of diagnosis, comorbidity, and use of selected drugs. Cox proportional hazard models were used to compute hazard ratios (HRs) and 95% confidence intervals (CI) for all-cause death associated with prediagnostic statin use.

RESULTS

A total of 339 GBM patients were included in the analyses. Of these, 325 died during median follow-up of 6.9 months (interquartile range: 3.8-13.4 months). Prediagnostic statin use was associated with a reduced HR of death (0.79; 95% CI: 0.63-1.00). The HRs decreased with increasing duration or intensity of prediagnostic statin use [long-term (≥ 5 years) statin use: HR 0.75 (95% CI: 0.47-1.20); high-intensity statin use: HR 0.66 (95% CI: 0.44-0.98)]. Additional adjustment for oncotherapeutic modalities yielded similar results (overall HR 0.80, 95% CI: 0.63-1.01).

CONCLUSION

Long-term prediagnostic statin use may improve survival following GBM.