Brain tumor biomarkers for research, clinics, and registries - The 2021 Brain Tumor Epidemiology Consortium meeting report.

The Brain Tumor Epidemiology Consortium (BTEC) is an international consortium that fosters interdisciplinary collaborations focusing on research related to the etiology, outcomes, and prevention of brain tumors. The 21st annual BTEC meeting with the theme "Brain Tumor Biomarkers for Research, Clinics, and Registries" was held virtually from June 22 to 24, 2021. Scientists from North America and Europe, representing a broad range of brain tumor research interests, presented recent research and progress in the field. The meeting content is summarized in the following report.

Attitudes Toward Euthanasia: A Longitudinal Analysis of the Role of Economic, Cultural, and Health-Related Factors.

CONTEXT: It is crucial that physicians understand differing attitudes toward euthanasia and which factors to consider when discussing end-of-life decisions with patients and families from diverse backgrounds. OBJECTIVES: To investigate how attitudes toward euthanasia differ among countries, how they change, and how economic, religious, and health-related factors affect these attitudes. METHODS: We analyzed attitudes toward euthanasia and economic, religious, and health-related indicators using longitudinal (1981-2018) World Values Survey (WVS) data. They included 62 countries with at least a 15-year, three-wave, time series (total n = 389,243 participants). Each national survey interviewed representative samples of adults (mean = 1405). RESULTS: In the latest wave, The Netherlands had the most favorable views of euthanasia (10-point scale with 1 = least justifiable: mean = 7.47) and Jordan the least (mean = 1.50). Residents of 23 of 24 high-income countries came to view euthanasia as more justifiable, while residents of 12 of 38 middle- and low-income countries came to view it as less justifiable over time. The higher GDP per-capita at the time of survey, the more euthanasia was accepted (r = 0.703; P< 0.0001); the more important respondents viewed religion as being, the less euthanasia was accepted (r = -0.834; P< 0.0001); the higher life expectancy and the lower infant mortality were, the more euthanasia was accepted (r = 0.669; P< 0.0001/r = -0.716; P< 0.0001). CONCLUSION: Euthanasia-related attitudes differ widely depending on the cultural context; changes over time varied in both directions; euthanasia-related attitudes were associated with economic, religious and health-related factors. With globalization increasing cultural diversity, these findings can inform physicians' communication about end-of-life decisions with patients and families from diverse backgrounds.

Brain tumor disparities: From biology to social determinants - The 2019 Brain Tumor Epidemiology Consortium meeting report.

The Brain Tumor Epidemiology Consortium (BTEC) is an international consortium that fosters international and interdisciplinary collaborations focusing on research related to the etiology, outcomes, and prevention of brain tumors. The 20th annual BTEC meeting with the theme "Brain tumor Disparities: From Biology to Social Determinants" was held in Los Angeles, CA, USA, on June 6 - 8, 2019. Scientists from the United States and Europe representing a broad range of brain tumor research disciplines presented their research findings at the meeting. The scientific content of the meeting is summarized below.

Advancing brain tumor epidemiology - multi-level integration and international collaboration: The 2018 Brain Tumor Epidemiology Consortium meeting report.

The Brain Tumor Epidemiology Consortium (BTEC) is an international consortium that aims to foster multicenter and inter-disciplinary collaborations that focus on research related to the etiology, outcomes, and prevention of brain tumors. The 19th annual BTEC meeting was held in Copenhagen, Denmark, on June 19 - 21, 2018. The meeting focused on forming international collaborations and integrating multiple data types for the next generation of studies in brain tumor epidemiology. The next BTEC meeting will be held in Southern California in June 2019.
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Anaerobic muscle strengthening physical activity and depression severity among USA adults.

We investigated the association between depression and anaerobic physical activity (while controlling aerobic physical activity), using a nationally representative sample of USA adults (n = 7354) who participated in the cross sectional National Health and Nutrition Examination Survey (NHANES, 1999-2006). We defined depression using the validated "Patient Health Questionnaire" (PHQ9) scale of 0-27 as PHQ9 ≥ 10. Severity of depression was classified by clinically established PHQ9 levels: mild (5-9), dysthymic (10-14), moderate (15-19), and major depression (≥20). We used logistic regression to estimate adjusted odds ratios of depression associated with distinct types of activity (only aerobic, only anaerobic, combined regime). We used multinomial logistic regression to examine associations of anaerobic activity with various severity levels of depression (mild, dysthymic, moderate, and major depression) with adjustment for aerobic activity. Women had higher prevalence of depression than men (8.4% versus 5.7%), whereas anaerobic muscle strengthening activity was more common in men than women (35% versus 24%). Adjusting for aerobic activity, anaerobic activity was inversely associated with depression (PHQ9 ≥ 10) in women under 50 (OR = 0.57; 95%CI = 0.41-0.81), all women (OR = 0.59; 0.43-0.80), men under 50 (OR = 0.85; 0.58-1.2), and all men (OR = 0.72; 0.51-1.01). Anaerobic activity was inversely associated with severity level of depressive symptoms in women and men. The combined regimen of anaerobic muscle strengthening activity and meeting the Physical Activity Guideline for America (PAGA) was related to the lowest odds ratio of depression in women (OR = 0.50; 95%CI = 0.33-0.75) and men (OR = 0.39; 95%CI = 0.23-0.62). Independent of aerobic physical activity, anaerobic muscle strengthening activity is significantly and inversely associated with depression among USA adults.

Brain tumor epidemiology in the era of precision medicine: The 2017 Brain Tumor Epidemiology Consortium meeting report.

The Brain Tumor Epidemiology Consortium (BTEC) is an international consortium that aims to advance the development of multicenter and interdisciplinary collaborations that focus on research related to the etiology, outcomes, and prevention of brain tumors. The 18th annual BTEC meeting was held in Banff, AB, Canada, on June 27 - 29, 2017. The meeting focused on the intersection between epidemiology and precision medicine, that is, the use of molecular indicators of risk, early disease and prognosis or precision epidemiology. While traditional epidemiologic approaches group large numbers of participants for statistical power, precision epidemiology is founded on the uniqueness and biology of individual disease characteristics. With this in mind, plenary speakers described the molecular heterogeneity of adult and pediatric brain tumors and how those characteristics are currently being used to guide therapy and etiologic research. Rare subtypes and novel mechanisms for recruitment of individuals for research on brain tumors were discussed along with concepts and methodology related to biological and etiologic heterogeneity. The incorporation of relevant molecular classifiers into population registries was emphasized for its role in future research endeavors, ensuring the accessibility of such tools for researchers and clinicians seeking to improve the lives of individuals with brain tumors and those at risk. The next BTEC meeting will be held in Copenhagen, Denmark, in June 2018.
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A nested case-control study of 277 prediagnostic serum cytokines and glioma.

Recent research shows bidirectional communication between the normal brain and the peripheral immune system. Glioma is a primary brain tumor characterized by systemic immunosuppression. To better understand gliomagenesis, we evaluated associations between 277 prediagnostic serum cytokines and glioma. We used glioma (n = 487) and matched control (n = 487) specimens from the Janus Serum Bank Cohort in Oslo, Norway. Conditional logistic regression allowed us to identify those cytokines that were individually associated with glioma. Next, we used heat maps to compare case to control Pearson correlation matrices of 12 cytokines modeled in an in silico study of the interaction between the microenvironment and the tumor. We did the same for case-control correlation matrices of lasso-selected cytokines and all 277 cytokines in the data set. Cytokines related to glioma risk (P ≤ .05) more than 10 years before diagnosis are sIL10RB, VEGF, beta-Catenin and CCL22. LIF was associated with decreased glioma risk within five years before glioma diagnosis (odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.23, 0.94). After adjustment for cytokines above, the previously observed interaction between IL4 and sIL4RA persisted (> 20 years before diagnosis, OR = 1.72, 95% CI = 1.20, 2.47). In addition, during this period, case correlations among 12 cytokines were weaker than were those among controls. This pattern was also observed among 30 lasso- selected cytokines and all 277 cytokines. We identified four cytokines and one interaction term that were independently related to glioma risk. We have documented prediagnostic changes in serum cytokine levels that may reflect the presence of a preclinical tumor.

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.

Association between prediagnostic glucose, triglycerides, cholesterol and meningioma, and reverse causality.

BACKGROUND: Although meningioma is a benign tumour, it may cause significant morbidity. Obesity and diabetes are positively associated with meningioma. To evaluate the potential effects of obesity-related prediagnostic glucose, triglycerides and cholesterol on meningioma and of prediagnostic meningioma on these biomarkers, we conducted a cohort study. METHODS: We identified 41 355 individuals in the Apolipoprotein MOrtality RISk cohort with values for these biomarkers within 15 years before meningioma diagnosis, death, migration or the end of follow-up. We then estimated hazard ratios (HRs) and their interactions with time and age using Cox regression. RESULTS: Meningioma was diagnosed in 181 women and 115 men whose median follow-up time was 7 years. Fasting serum glucose level was inversely related to meningioma among women (Ptrend=0.0006) but not men (Ptrend=0.24). Prediagnostic diabetes was inversely related to meningioma in both sexes combined (HR=0.45, 95% confidence interval (CI) 0.29-0.71), as was serum cholesterol within the year before diagnosis (HR=0.50, 95% CI 0.34-0.72). CONCLUSIONS: Paradoxically, hyperglycaemia is inversely associated with meningioma in women. This finding does not necessarily negate the positive role of obesity or diabetes in meningioma development; rather, it may indicate that their effects depend on the stage of development. Furthermore, the prediagnostic tumour may reduce serum cholesterol levels.

Birth Size Characteristics and Risk of Brain Tumors in Early Adulthood: Results from a Swedish Cohort Study.

BACKGROUND: Despite extensive research on the effect of birth size characteristics on childhood brain tumors, very few studies have evaluated the effect of birth size characteristics on the risk of adult brain tumor, and they have provided inconsistent results. METHODS: All individuals born in Sweden between 1973 and 1995 who were still alive and cancer free at their 15th birthday were included in the study (n = 2,032,727). At the end of the study period (December 31, 2010), the study participants were 15 to 37 years old. Incident cases of primary brain tumors were identified through the Swedish Cancer Register. RESULTS: No association was observed between any birth size characteristics and glioma, although an indication of increased glioma risk associated with high birth weight, or being large for gestational age at birth, was found among men [relative risk (RR) = 1.36, 95% confidence interval (CI), 0.97-1.90; RR = 1.44, 95% CI, 0.99-2.09, respectively]. An increased risk of meningioma was observed among individuals born with a large head circumference (RR = 1.76, 95% CI, 1.01-3.05). Large head circumference was also associated with an elevated risk of neuroma (RR = 1.86, 95% CI, 0.94-3.68). Being born small for gestational age was also related to a higher risk of neuroma (RR = 2.50, 95% CI, 1.31-4.78). CONCLUSION: Selected birth size characteristics were associated with increased risk of some brain tumor subtypes in young adults. IMPACT: We have presented additional evidence suggesting that birth size characteristics are associated with subsequent primary brain tumor risk in young adults. Cancer Epidemiol Biomarkers Prev; 25(4); 678-85. ©2016 AACR.

Maternal smoking during pregnancy and the risk of childhood brain tumors: Results from a Swedish cohort study.

BACKGROUND: Tobacco metabolites and carcinogens can be found in placental and umbilical cord tissues of fetuses exposed to maternal smoking. However, studies regarding maternal smoking during pregnancy and childhood brain tumor (CBT) have shown inconsistent results. METHODS: All children born in Sweden between 1983 and 2010 and with information about maternal smoking during pregnancy, obtained from the Swedish Medical Birth Register, were included in this population based cohort study (n=2,577,305). CBT cases were identified from the National Cancer Register. Cox regression models were used to estimate the effect of maternal smoking during pregnancy on the risk of CBTs. RESULTS: We identified 1039 cases of CBT in the cohort. Overall, there was little or no effect of maternal smoking during pregnancy on the risk of CBTs. However, in analyses stratified by age at diagnosis and child's sex, positive associations were found among 5-9 years old children. In this age interval, maternal smoking during pregnancy was associated with an increased risk of all CBTs combined only among male children (RR=1.50, 95% CI 0.96-2.34), while for astrocytoma there was a positive association in both male (RR=2.00, 95% CI 1.02-3.91) and female children (RR=1.80, 95% CI 0.85-3.82). CONCLUSION: Results from this large Swedish cohort study suggest that even though maternal smoking during pregnancy has a limited overall effect on CBTs, it may increase the risk of astrocytomas.

Association between Prediagnostic Allergy-Related Serum Cytokines and Glioma.

Allergy is inversely related to glioma risk. To determine whether prediagnostic allergy-related serum proteins are associated with glioma, we conducted a nested case-control study of seven cytokines (IL4, IL13, IL5, IL6, IL10, IFNG, TGFB2), two soluble cytokine receptors (sIL4RA, sIL13RA2) and three allergy-related transcription factors (FOXP3, STAT3, STAT6) using serum specimens from the Janus Serum Bank Cohort in Oslo, Norway. Blood donors subsequently diagnosed with glioma (n = 487) were matched to controls (n = 487) on age and date of blood draw and sex. We first estimated individual effects of the 12 serum proteins and then interactions between IL4 and IL13 and their receptors using conditional logistic regression. We next tested equality of case-control inter-correlations among the 12 serum proteins. We found that TGFB2 is inversely related to glioblastoma (Odds Ratio (OR) = 0.87, 95% Confidence Interval (CI)) = 0.76, 0.98). In addition, ≤ 5 years before diagnosis, we observed associations between IL4 (OR = 0.82, 95% CI = 0.66, 1.01), sIL4RA (OR = 0.80, 95% CI = 0.65, 1.00), their interaction (OR = 1.06, 95% CI = 1.01, 1.12) and glioblastoma. This interaction was apparent > 20 years before diagnosis (IL4-sIL4RA OR = 1.20, 95% CI = 1.05, 1.37). Findings for glioma were similar. Case correlations were different from control correlations stratified on time before diagnosis. Five years or less before diagnosis, correlations among case serum proteins were weaker than were those among controls. Our findings suggest that IL4 and sIL4RA reduce glioma risk long before diagnosis and early gliomagenesis affects circulating immune function proteins.

Association Between Prediagnostic Serum 25-Hydroxyvitamin D Concentration and Glioma.

There are no previous studies of the association between prediagnostic serum vitamin D concentration and glioma. Vitamin D has immunosuppressive properties; as does glioma. It was, therefore, our hypothesis that elevated vitamin D concentration would increase glioma risk. We conducted a nested case-control study using specimens from the Janus Serum Bank cohort in Norway. Blood donors who were subsequently diagnosed with glioma (n = 592), between 1974 and 2007, were matched to donors without glioma (n = 1112) on date and age at blood collection and sex. We measured 25-hydroxyvitamin D [25(OH)D], an indicator of vitamin D availability, using liquid chromatography coupled with mass spectrometry. Seasonally adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated for each control quintile of 25(OH)D using conditional logistic regression. Among men diagnosed with high grade glioma >56, we found a negative trend (P = .04). Men diagnosed ≤ 56 showed a borderline positive trend (P = .08). High levels (>66 nmol/L) of 25(OH)D in men >56 were inversely related to high grade glioma from ≥2 yr before diagnosis (OR = 0.59; 95% CI = 0.38, 0.91) to ≥15 yr before diagnosis (OR = 0.61; 95% CI = 0.38,0.96). Our findings are consistent long before glioma diagnosis and are therefore unlikely to reflect preclinical disease.

A mathematical model of pre-diagnostic glioma growth.

Due to their location, the malignant gliomas of the brain in humans are very difficult to treat in advanced stages. Blood-based biomarkers for glioma are needed for more accurate evaluation of treatment response as well as early diagnosis. However, biomarker research in primary brain tumors is challenging given their relative rarity and genetic diversity. It is further complicated by variations in the permeability of the blood brain barrier that affects the amount of marker released into the bloodstream. Inspired by recent temporal data indicating a possible decrease in serum glucose levels in patients with gliomas yet to be diagnosed, we present an ordinary differential equation model to capture early stage glioma growth. The model contains glioma-glucose-immune interactions and poses a potential mechanism by which this glucose drop can be explained. We present numerical simulations, parameter sensitivity analysis, linear stability analysis and a numerical experiment whereby we show how a dormant glioma can become malignant.

Childhood brain tumor epidemiology: a brain tumor epidemiology consortium review.

Childhood brain tumors are the most common pediatric solid tumor and include several histologic subtypes. Although progress has been made in improving survival rates for some subtypes, understanding of risk factors for childhood brain tumors remains limited to a few genetic syndromes and ionizing radiation to the head and neck. In this report, we review descriptive and analytical epidemiology childhood brain tumor studies from the past decade and highlight priority areas for future epidemiology investigations and methodological work that is needed to advance our understanding of childhood brain tumor causes. Specifically, we summarize the results of a review of studies published since 2004 that have analyzed incidence and survival in different international regions and that have examined potential genetic, immune system, developmental and birth characteristics, and environmental risk factors. Cancer Epidemiol Biomarkers Prev; 23(12); 2716-36. ©2014 AACR.

The epidemiology of glioma in adults: a "state of the science" review.

Gliomas are the most common primary intracranial tumor, representing 81% of malignant brain tumors. Although relatively rare, they cause significant mortality and morbidity. Glioblastoma, the most common glioma histology (∼45% of all gliomas), has a 5-year relative survival of ∼5%. A small portion of these tumors are caused by Mendelian disorders, including neurofibromatosis, tuberous sclerosis, and Li-Fraumeni syndrome. Genomic analyses of glioma have also produced new evidence about risk and prognosis. Recently discovered biomarkers that indicate improved survival include O6-methylguanine-DNA methyltransferase methylation, isocitrate dehydrogenase mutation, and a glioma cytosine-phosphate-guanine island methylator phenotype. Genome-wide association studies have identified heritable risk alleles within 7 genes that are associated with increased risk of glioma. Many risk factors have been examined as potential contributors to glioma risk. Most significantly, these include an increase in risk by exposure to ionizing radiation and a decrease in risk by history of allergies or atopic disease(s). The potential influence of occupational exposures and cellular phones has also been examined, with inconclusive results. We provide a "state of the science" review of current research into causes and risk factors for gliomas in adults.