Occupation and the risk of adult glioma in the United States

Incidence trends of adult glioma in Norway and its association with occupation and education: A registry-based cohort study

BACKGROUND

Gliomas constitute 75 % of all malignant primary adult brain tumors. Being the most frequent histologic subtype, glioblastomas (GBMs) cause substantial morbidity and mortality worldwide and the Nordic countries have some of the highest incidence rates in the world. Therefore, we investigated the incidence of gliomas in Norway including time trends and associations with education and occupation.

METHODS

We retrieved individual-level data from databases at Statistics Norway containing information on education and occupation and linked them to data on adult glioma patients diagnosed during 2004-21 from the Cancer Registry of Norway. Age-standardized incidence rates (ASIRs) (World Standard Population) were calculated and analyzed with regards to sex and morphology. Poisson regression was used to test for time-trends, and to analyze the associations between education, occupation and glioma incidence, adjusted for age, sex, and calendar year. Estimates were reported as incidence rate ratios (IRRs) with 95 % confidence intervals (CIs).

RESULTS

The overall ASIR of gliomas (per 100,000 person-years) was 7.1 (95 % CI 6.9-7.3), with no specific time trend during the study period. The incidence increased with age. Compared to the other subtypes, GBMs were diagnosed at older ages. The risks of developing glioma overall and GBM were associated with occupation but not with educational level. The relative risk of glioma and GBM were respectively 1.17 (95 % CI 1.05-1.31) and 1.17 (95 % CI 1.02-1.35) among high-skilled white-collar workers compared to blue-collar workers.

CONCLUSIONS

The overall and sex-specific ASIRs of gliomas and GBMs did not show any noticeable time trends. The higher risk of developing glioma overall and GBM in high-skilled white-collar workers compared to blue-collar workers calls for further investigations.

Occupational Cancers among Employed Women: A Narrative Review

The facts that occupational cancer in women is under-investigated, with few in-depth analyses are well known. In recent decades the workforce has changed, with an increasing number of women employed. Therefore, the inclusion of women in occupational cancer studies has become more urgent and feasible than in the past decades. The difficulties to evaluate occupational causes of female gynecologic tumors in most past cohorts and the potential variation in outcome responses between men and women must be taken into consideration. This narrative review discusses women's occupational cancer as a current area of research, focusing on three groups of workers characterized by peculiar exposure to occupational carcinogens and where women are often employed: beauticians and hairdressers; farmers; and healthcare workers. We discuss the most relevant cancers in each working category, with a particular focus on female breast cancer. In the three industries reviewed in detail, there are some risk factors which may affect primarily women, inducing breast cancer and cervical cancer, as well as risk factors that are carcinogenic in both genders, but whose effects are less well known in women.

Adherence to plant-based dietary patterns in relation to glioma: a case-control study

Available evidence suggests a favorable association between adherence to a plant-based diet and disease prevention, but data on the link between such dietary intakes and cancer are scarce. We examined the association between the overall plant-based diet (PDI), healthy plant-based diet (hPDI), and unhealthy plant-based diet (uPDI) and risk of glioma. This case–control study was conducted on 128 newly diagnosed glioma patients, and 256 hospital-based controls. Cases were diagnosed by pathological test and controls were selected from hospitalized people in orthopedic and surgical wards. Dietary intakes were assessed using a validated Block-format 123-items food frequency questionnaire. Scores of plant-based dietary patterns were calculated using the method suggested by Satija et al. After controlling for potential confounders, individuals with higher scores of PDI (OR: 0.54, 95% CI: 0.32–0.91, P-trend < 0.001) and hPDI (OR: 0.32, 95% CI: 0.18–0.57, P-trend < 0.001) had significantly lower odds of glioma compared with those with the lowest scores. This association did not change in the fully adjusted model; such that subjects in the highest tertile of PDI and hPDI were 69% and 71% less likely to have glioma compared with those in the lowest tertile. In contrast, higher scores of uPDI was significantly associated with a greater odds of glioma (OR: 2.85, 95% CI: 1.26–6.47, P-trend = 0.02). Adherence to PDI and hPDI was associated with a lower odds of glioma, while greater adherence to uPDI was directly associated with the likelihood of glioma. Further prospective cohort studies are needed to examine our findings.

Association of strong risk of hTERT gene polymorphic variants to malignant glioma and its prognostic implications with respect to different histological types and survival of glioma cases

BACKGROUND

Germline genetic variants of human telomerase reverse transcriptase (hTERT) are known to predispose for various malignancies, including glioma. The present study investigated genetic variation of hTERT T/G (rs2736100) and hTERT G/A (rs2736098) with respect to glioma risk.

METHODS

Confirmed cases (n = 106) were tested against 210 cancer-free healthy controls by the polymerase chain reaction-restriction fragment length polymorphism technique for genotyping.

RESULTS

Homozygous variant 'GG' genotype of rs2736100 frequency was > 4-fold significantly different in cases versus controls (39.6% 17.2%; p < 0.0001). Furthermore, variant 'G' allele was found to be significantly associated with cases (0.5 versus 0.2 in controls; p < 0.0001). Homozygous variant rs2736098 'AA' genotype (35.8% versus 23.8%) and allele 'A' (0.49 versus 0.34) showed a marked significant difference in cases and controls, respectively (p < 0.05). In hTERT rs2736100, the GG genotype significantly presented more in higher grades and GBM (p < 0.0001). Furthermore, the GG variant of hTERT rs2736100 had a poor probability with respect to the overall survival of patients compared to TG and TT genotypes (log rank p = 0.03). Interestingly, two haplotypes of hTERT rs2736100/rs2736098 were identified as GG and GA that conferred a > 3- and 5-fold risk to glioma patients respectively, where variant G/A haplotype was observed to have the highest impact with respect to glioma risk (p < 0.0001).

CONCLUSIONS

The results of the present study indicate that hTERT rs2736098 and rs2736100 variants play an important role in conferring a strong risk of developing glioma. Furthermore, hTERT rs2736100 GG variant appears to play a role in the bad prognosis of glioma patients. Haplotypes GG and GA could prove to be vital tools for monitoring risk in glioma patients.

Associations ofVEGFAandKDRsingle-nucleotide polymorphisms and increased risk and aggressiveness of high-grade gliomas

Angiogenesis, induced by the vascular endothelial growth factor A through its ligation to the vascular endothelial growth receptor 2, has been described as a crucial point in high-grade glioma development. The aim of this study was to evaluate the influence of VEGFA–2578C/A, −2489C/T, −1154G/A, −634G/C, and −460C/T, and KDR–604T/C, −271G/A, +1192G/A, and +1719A/T single-nucleotide polymorphisms on risk and clinicopathological aspects of high-grade glioma. This case–control study enrolled 205 high-grade glioma patients and 205 controls. Individuals with VEGFA–2578 CC or CA, VEGFA–1154 GG, VEGFA–634 GC or CC, and VEGFA–460 CT or TT genotypes were under 2.56, 1.53, 1.54, and 1.84 increased risks of high-grade glioma, compared to others, respectively. And 1.61, 2.66, 2.52, 2.53, and 2.02 increased risks of high-grade glioma were seen in individuals with VEGFA–2578 CC plus VEGFA–1154 GG, VEGFA–2578 CC or CA plus VEGFA–634 GC or CC, VEGFA–2578 CC or CA plus VEGFA–460 CT or TT, VEGFA–1154 GG or GA plus VEGFA–634 GC or CC, and VEGFA 634 GC or CC plus VEGFA–460 CT or TT combined genotypes, respectively, when compared to others. The “CAGT” haplotype of KDR single-nucleotide polymorphisms was more common in patients with grade IV than in those with grade III tumors, and individuals carrying this haplotype were at 1.76 increased risk of developing grade IV tumors than others. We present, for the first time, preliminary evidence that VEGFA–2578C/A and VEGFA–1154G/A single-nucleotide polymorphisms increases high-grade glioma risk, and “CAGT” haplotype of the KDR gene alters high-grade glioma aggressiveness and risk of grade IV tumors in Brazil.

Agricultural exposures to carbamate herbicides and fungicides and central nervous system tumour incidence in the cohort AGRICAN

BACKGROUND

Pesticides exposures could be implicated in the excess of Central Nervous System (CNS) tumors observed in farmers, but evidence concerning individual pesticides remains limited. Carbamate derivative pesticides, including herbicides and fungicides (i.e. (thio/dithio)-carbamates), have shown evidence of carcinogenicity in experimental studies in animals. In the French AGRICAN cohort, we assessed the associations between potential exposures to carbamate herbicides and fungicides and the incidence of CNS tumors, overall and by histological subtype.

METHODS

AGRICAN enrolled 181,842 participants involved in agriculture. Incident CNS tumors were identified by linkage with cancer registries from enrollment (2005-2007) until 2013. Individual exposures were assessed by combining information on lifetime periods of pesticide use on crops and the French crop-exposure matrix PESTIMAT, for each of the 14 carbamate and thiocarbamate herbicides and the 16 carbamate and dithiocarbamate fungicides registered in France since 1950. Associations were estimated using proportional hazard models with age as the underlying timescale, adjusting for gender, educational level and smoking.

RESULTS

During an average follow-up of 6.9 years, 381 incident cases of CNS tumors occurred, including 164 gliomas and 134 meningiomas. Analyses showed increased risks of CNS tumors with overall exposure to carbamate fungicides (Hazard Ratio, HR = 1.88; 95% CI: 1.27-2.79) and, to a lesser extent, to carbamate herbicides (HR = 1.44; 95% CI: 0.94-2.22). Positive associations were observed with specific carbamates, including some fungicides (mancozeb, maneb, metiram) and herbicides (chlorpropham, propham, diallate) already suspected of being carcinogens in humans.

CONCLUSIONS

Although some associations need to be corroborate in further studies and should be interpreted cautiously, these findings provide additional carcinogenicity evidence for several carbamate fungicides and herbicides.

Interactions between occupational exposure to extremely low frequency magnetic fields and chemicals for brain tumour risk in the INTEROCC study

OBJECTIVES

In absence of clear evidence regarding possible effects of occupational chemical exposures on brain tumour aetiology, it is worthwhile to explore the hypothesis that such exposures might act on brain tumour risk in interaction with occupational exposure to extremely low frequency magnetic fields (ELF).

METHODS

INTEROCC is a seven-country (Australia, Canada, France, Germany, Israel, New Zealand and UK), population-based, case-control study, based on the larger INTERPHONE study. Incident cases of primary glioma and meningioma were ascertained from 2000 to 2004. Job titles were coded into standard international occupational classifications and estimates of ELF and chemical exposures were assigned based on job-exposure matrices. Dichotomous indicators of cumulative ELF (≥50th vs <50th percentile, 1-4 year exposure time window) and chemical exposures (ever vs never, 5-year lag) were created. Interaction was assessed on both the additive and multiplicative scales.

RESULTS

A total of 1939 glioma cases, 1822 meningioma cases and 5404 controls were included in the analysis, using conditional logistic regression. There was no clear evidence for interactions between ELF and any of the chemical exposures assessed for either glioma or meningioma risk. For glioma, subjects in the low ELF/metal exposed group had a lower risk than would be predicted from marginal effects. Results were similar according to different exposure time windows, to cut-points of exposure or in exposed-only analyses.

CONCLUSIONS

There was no clear evidence for interactions between occupational ELF and chemical exposures in relation to glioma or meningioma risk observed. Further research with more refined estimates of occupational exposures is recommended.

Association between butchers and cancer mortality and incidence: A systematic review and meta-analysis

BACKGROUND

In this study, we evaluated whether increased risks of mortality and cancer incidence exist among butchers worldwide. To achieve this goal, we conducted a systematic review and meta-analysis to investigate the correlations of the risks of cancer death and incidence with male and female butchers.

METHODS

We obtained data by performing a comprehensive literature search in several databases for eligible studies published before March 2017. Multivariable-adjusted standardized mortality ratios (SMRs) and odds ratio (OR), as well as associated 95% confidence intervals (CIs) and those by subgroups, were extracted and pooled.

RESULTS

A total of 17 observational studies comprising 397,726 participants were included in the meta-analysis. The butcher occupation was not associated with all-cancer mortality risk, with pooled overall SMRs of 1.07 (95% CI 0.96-1.20). However, the pooled ORs revealed that butchers hold an elevated risk of total cancer incidence (OR, 1.51; 95% CI, 1.33-1.73). No proof of publication bias was obtained, and the findings were consistent in the subgroup analyses.

CONCLUSION

Our results suggest that working as butchers did not significantly influence all-cancer mortality risk but significantly contributed to elevated all-cancer incidence risk. Nevertheless, well-designed observational studies on this topic are necessary to confirm and update our findings.

Genetic Variations of Kinase Inserts Domain Receptor (KDR) Gene Are Associated with the Risk of Astrocytomas

Astrocytomas is one of the most common central nervous system (CNS) tumors with high mortality rate. Kinase insert domain receptor (KDR) is involved in the regulation of tumor angiogenesis, migration, and vascular permeability. The aim of the study was to explore the relationship between KDR polymorphisms and risk of astrocytomas. Blood samples were collected from 157 astrocytomas patients and 160 healthy controls. Three tag-SNPs (rs2071559C/T, rs2305948T/C, and rs1870377A/T) were identified from the International HapMap Project Databases and genotyped using the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We evaluated the astrocytomas risk caused by individual SNPs and haplotype using odds ratios (ORs) and their 95 % confidence intervals (CIs). In the overall individual SNP analysis, the C allele of rs2071559 was correlated with an increased risk of astrocytomas. However, individuals with mutant allele A and genotype TA + AA of rs1870377 showed a protective effect against astrocytomas. Subgroup analysis based on WHO tumor grade revealed that the C allele of rs2071559 had more influence with the risk of astrocytomas in the grade III-IV (OR = 1.91) subgroup than the grade I-II (OR = 1.47) group. Genotype TT of rs2305948 was found to be significantly associated with susceptibility of astrocytomas only in the grade III-IV subgroup. The protective effect of rs1870377 did not reveal significant difference between the grade III-IV and grade I-II subgroups. Meanwhile, stratified analysis demonstrated that mutation of rs2071559 and rs2305948 could elevate the risk of astrocytomas more significantly in the subgroup of smokers than the nonsmokers. Interestingly, the protective effect of rs1870377 was more obvious in the nonsmokers than the smokers. Additionally, haplotype-specific analysis showed that haplotype CCT and CTT were related with an increased risk of astrocytomas. We found that individual with variants of rs2071559*C and rs2305948*T might significantly elevate the risk of astrocytomas, while mutants of rs1870377*A was associated with the decreased risk of astrocytomas. Further studies about ethnically diverse populations with larger sample size should be performed to confirm the correlation between KDR gene polymorphisms and risk of astrocytomas.

Angiotensin-converting enzyme insertion/deletion gene polymorphisms is associated with risk of glioma in a Chinese population

INTRODUCTION

The insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene has recently been linked to the pathogenesis and progression of human cancers. The aim of this study was to evaluate the potential association between ACE I/D polymorphism and glioma in a Chinese population.

MATERIALS AND METHODS

A case-control study involving patients with 800 glioma and 800 controls was conducted. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay was applied to assess the ACE I/D genotypes.

RESULTS

Glioma cases had a significantly higher frequency of DD genotype [odds ratio (OR) = 1.61, 95% confidence interval (CI) = 1.12, 2.32; p = 0.01] than controls. When stratified by the grade of glioma, cases with WHO IV glioma had a significantly higher frequency of DD genotype (OR = 1.51, 95% CI = 1.03, 2.21; p = 0.03). When stratified by the histology of glioma, there was no significant difference in the distribution of each genotype.

CONCLUSION

Our study suggested that the ACE DD genotype was associated with a higher glioma risk in this Chinese population. To the best of our knowledge, this is the first report describing the potential association between ACE I/D polymorphism and glioma. Additional studies are needed to confirm this finding.

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.

Temporal and Geographic Clustering of Polyomavirus-Associated Olfactory Tumors in 10 Free-Ranging Raccoons (Procyon lotor)

Reports of primary nervous system tumors in wild raccoons are extremely rare. Olfactory tumors were diagnosed postmortem in 9 free-ranging raccoons from 4 contiguous counties in California and 1 raccoon from Oregon within a 26-month period between 2010 and 2012. We describe the geographic and temporal features of these 10 cases, including the laboratory diagnostic investigations and the neuropathologic, immunohistochemical, and ultrastructural characteristics of these tumors in the affected animals. All 9 raccoons from California were found within a localized geographic region of the San Francisco Bay Area (within a 44.13-km radius). The tight temporal and geographic clustering and consistent anatomic location in the olfactory system of tumor types not previously described in raccoons (malignant peripheral nerve sheath tumors and undifferentiated sarcomas) strongly suggest either a common cause or a precipitating factor leading to induction or potentiation of neuro-oncogenesis and so prompted an extensive diagnostic investigation to explore possible oncogenic infectious and/or toxic causes. By a consensus polymerase chain reaction strategy, a novel, recently reported polyomavirus called raccoon polyomavirus was identified in all 10 tumors but not in the normal brain tissue from the affected animals, suggesting that the virus might play a role in neuro-oncogenesis. In addition, expression of the viral protein T antigen was detected in all tumors containing the viral sequences. We discuss the potential role of raccoon polyomavirus as an oncogenic virus.

Three single nucleotide polymorphisms of the vascular endothelial growth factor (VEGF) gene and glioma risk in a Chinese population

OBJECTIVE

To investigate the association between three single nucleotide polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) gene and the risk of glioma in a Han Chinese population.

METHODS

This hospital-based case-control study used polymerase chain reaction-restriction fragment length polymorphism analysis to detect three SNPs (-634 G/C, +936 C/T and +1612 G/A) of the VEGF gene in patients with glioma compared with healthy control subjects.

RESULTS

The study investigated 880 patients with gliomas and 880 age- and sex-matched healthy control subjects. Patients with gliomas had a significantly higher frequency of the -634 CC genotype (odds ratio [OR] 1.35, 95% confidence interval [CI] 1.05, 1.75) and the +936 TT (OR 1.73, 95% CI 1.20, 2.48) genotype compared with the control subjects. Patients with glioblastomas had a significantly higher frequency of the -634 CC and +936 TT genotypes. Patients with grade IV gliomas had a significantly higher frequency of the -634 CC and +936 TT genotypes. The +1612 G/A polymorphisms were not associated with glioma risk.

CONCLUSION

The VEGF - 634 CC and +936 TT genotypes were associated with a higher risk of glioma in a Han Chinese population.

Association between the Thr241Met polymorphism of X-ray repair cross-complementing group 3 gene and glioma risk: evidence from a meta-analysis based on 4,136 cases and 5,233 controls

Genetic polymorphism of X-ray repair cross-complementing group 3 (XRCC3) Thr241Met has been implicated to alter the risk of glioma, but the results are controversial. Medline, PubMed, Embase, and Cochrane Library databases were independently searched by two investigators up to 13 July 2013. Summary odds ratios (OR) and 95% confidence interval (CI) for Thr241Met polymorphism and prostate cancer were calculated. Statistical analysis was performed with the software program Stata 12.0. A total of 10 independent studies, including 4,136 cases and 5,233 controls, were identified. Our analysis suggested that Thr241Met was not associated with glioma risk in overall population. In the subgroup analysis, we detected no significant association between Thr241Met polymorphism and glioma risk in different descent populations. Subgroup analysis was held by source of controls, significant association was found between this polymorphism and glioma risk for population-based studies (homozygote model: OR = 1.747, 95% CI = 1.123-2.717, Ph = 0.059, I(2) = 59.7%; recessive model, OR = 1.455, 95% CI = 1.179-1.795, Ph = 0.111, I(2) = 50.1%; allele model, OR = 1.258, 95% CI = 1.010-1.566, Ph = 0.011, I(2) = 72.9%). This meta-analysis showed the evidence that XRCC3 Thr241Met polymorphism was associated with a low risk of glioma development.

INTEROCC case-control study: lack of association between glioma tumors and occupational exposure to selected combustion products, dusts and other chemical agents

Background

The aim was to investigate possible associations between glioma (an aggressive type of brain cancer) and occupational exposure to selected agents: combustion products (diesel and gasoline exhaust emissions, benzo(a)pyrene), dusts (animal dust, asbestos, crystalline silica, wood dust) and some other chemical agents (formaldehyde, oil mist, sulphur dioxide).

Methods

The INTEROCC study included cases diagnosed with glioma during 2000–2004 in sub-regions of seven countries. Population controls, selected from various sampling frames in different centers, were frequency or individually matched to cases by sex, age and center. Face-to-face interviews with the subject or a proxy respondent were conducted by trained interviewers. Detailed information was collected on socio-economic and lifestyle characteristics, medical history and work history. Occupational exposure to the 10 selected agents was assessed by a job exposure matrix (JEM) which provides estimates of the probability and level of exposure for different occupations. Using a 25% probability of exposure in a given occupation in the JEM as the threshold for considering a worker exposed, the lifetime prevalence of exposure varied from about 1% to about 15% for the different agents. Associations between glioma and each of the 10 agents were estimated by conditional logistic regression, and using three separate exposure indices: i) ever vs. never; ii) lifetime cumulative exposure; iii) total duration of exposure.

Results

The study sample consisted of 1,800 glioma cases and 5,160 controls. Most odds ratio estimates were close to the null value. None of the ten agents displayed a significantly increased odds ratio nor any indication of dose–response relationships with cumulative exposure or with duration of exposure.

Conclusion

Thus, there was no evidence that these exposures influence risk of glioma.

Occupational exposure to chlorinated solvents and risks of glioma and meningioma in adults

OBJECTIVES

Chlorinated solvents are classified as probable or possible carcinogens. It is unknown whether exposure to these agents increases the risk of malignant or benign brain tumours. Our objective was to evaluate associations of brain tumour risk with occupational exposure to six chlorinated solvents (i.e., dichloromethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene and perchloroethylene).

METHODS

489 glioma cases, 197 meningioma cases and 799 controls were enrolled in a hospital-based case-control study conducted at three U.S.A. hospitals in Arizona, Massachusetts and Pennsylvania. Information about occupational history was obtained through a detailed inperson interview that included job-specific modules of questions such that the interview was tailored to each individual's particular work history. An industrial hygienist assessed potential solvent exposure based on this information and an exhaustive review of the relevant industrial hygiene literature. Unconditional logistic regression models were used to calculate OR and 95% CI for each solvent for ever/never, duration, cumulative, average weekly and highest exposure.

RESULTS

Overall, we found no consistent evidence of an increased risk of glioma or meningioma related to occupational exposure to the six chlorinated solvents evaluated. There was some suggestion of an association between carbon tetrachloride and glioma in analyses restricted to exposed subjects, with average weekly exposure above the median associated with increased risk compared with below the median exposure (OR = 7.1, 95% CI 1.1 to 45.2).

CONCLUSIONS

We found no consistent evidence for increased brain tumour risk related to chlorinated solvents.

The Upper Midwest Health Study: industry and occupation of glioma cases and controls

BACKGROUND

Understanding glioma etiology requires determining which environmental factors are associated with glioma. Upper Midwest Health Study case-control participant work histories collected 1995-1998 were evaluated for occupational associations with glioma. "Exposures of interest" from our study protocol comprise our a priori hypotheses.

MATERIALS AND METHODS

Year-long or longer jobs for 1,973 participants were assigned Standard Occupational Classifications (SOC) and Standard Industrial Classifications (SIC). The analysis file includes 8,078 SIC- and SOC-coded jobs. For each individual, SAS 9.2 programs collated employment with identical SIC-SOC coding. Distributions of longest "total employment duration" (total years worked in jobs with identical industry and occupation codes, including multiple jobs, and non-consecutive jobs) were compared between cases and controls, using an industrial hygiene algorithm to group occupations.

RESULTS

Longest employment duration was calculated for 780 cases and 1,156 controls. More case than control longest total employment duration was in the "engineer, architect" occupational group [16 cases, 10 controls, odds ratio (OR) 2.50, adjusted for age group, sex, age and education, 95% confidence interval (CI) 1.12-5.60]. Employment as a food processing worker [mostly butchers and meat cutters] was of borderline significance (27 cases, 21 controls, adjusted OR: 1.78, CI: 0.99-3.18).

CONCLUSIONS

Among our exposures of interest work as engineers or as butchers and meat cutters was associated with increased glioma risk. Significant associations could be due to chance, because of multiple comparisons, but similar findings have been reported for other glioma studies. Our results suggest some possible associations but by themselves could not provide conclusive evidence.

A functional polymorphism in the epidermal growth factor gene is associated with risk for glioma in a Chinese population

Epidermal growth factor (EGF) plays a key role in survival of neural and glial precursor cells. A single nucleotide polymorphism of the EGF gene +61G/A in the 5'-untranslated region has been reported to be associated with susceptibility to glioma. The purpose of this study was to investigate the potential association between EGF +61G/A and brain glioma in a Chinese population. A case-control study involving 180 patients with glioma and 360 controls was done. Polymerase chain reaction restriction fragment-length polymorphism assay was used to analyze the EGF +61G/A genotypes. Patients with glioma had a significantly higher frequency of AA genotype (odds ratio, 2.25; 95% confidence interval, 1.20, 4.21; p=0.01] than controls. When stratified by histologic features and World Health Organization grade of glioma, distribution of each genotype did not significantly differ. Our data suggested that the EGF +61G AA genotype was associated with a higher glioma risk in a Chinese population. This finding is in contrast with previous studies that reported the G allele as a risk factor for glioma in white patients.

Two common nonsynonymous paraoxonase 1 (PON1) gene polymorphisms and brain astrocytoma and meningioma

BACKGROUND

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.

METHODS

Seventy one consecutive patients with brain tumors (43 with astrocytoma grade II/III and 28 with meningioma) with ages ranging 21 to 76 years, and 220 healthy controls subjects were analyzed for the frequency of the nonsynonymous PON1 genotypes L55M rs854560 and Q192R rs662. All participants were adult Caucasian individuals recruited in the central area of Spain.

RESULTS

The frequencies of the PON1 genotypes and allelic variants of the polymorphisms PON1 L55M and PON1 Q192R did not differ significantly between patients with astrocytoma and meningioma and controls. The minor allele frequencies were as follows: PON1 55L, 0.398, 0.328 and 0.286 for patients with astrocytoma, meningioma and control individuals, respectively; PON1 192R, 0.341, 0.362 and 0.302 for patients with astrocytoma, meningioma and control individuals, respectively. Correction for age, gender, or education, made no difference in odds ratios and the p values remained non-significant. Haplotype association analyses did not identify any significant association with the risk of developing astrocytoma or meningioma.

CONCLUSIONS

Common nonsynonymous PON1 polymorphisms are not related with the risk of developing astrocytoma and meningioma.

Occupation and risk of glioma, meningioma and acoustic neuroma: results from a German case-control study (interphone study group, Germany)

BACKGROUND

Several epidemiological studies have investigated the association between occupation and brain tumour risk, but results have been inconclusive. We investigated the association between six occupational categories defined a priori: chemical, metal, agricultural, construction, electrical/electronic and transport, and the risk of glioma, meningioma and acoustic neuroma.

METHODS

In a population-based case-control study involving a total of 844 cases and 1688 controls conducted from 2000 to 2003, detailed information on life-long job histories was collected during personal interviews and used to create job calendars for each participant. Job title, job activity, job number, and the starting and ending dates of the activity were recorded for all activities with duration of at least 1 year. Reported occupational activities were coded according to the International Standard Classification of Occupations 1988 (ISCO 88). For the analyses we focused on six a priori defined occupational sectors, namely chemical, metal, agricultural, construction, electrical/electronic and transport. Multiple conditional logistic regression analysis was used to estimate odds ratios and their 95% confidence intervals.

RESULTS

Most of the observed odds ratios were close to 1.0 for ever having worked in the six occupational sectors and risk of glioma, meningioma and acoustic neuroma. Sub-group analyses according to duration of employment resulted in two elevated odds ratios with confidence intervals excluding unity.

CONCLUSIONS

We did not observe an increased risk of glioma or meningioma for occupations in the agricultural, construction, transport, chemical, electrical/electronic and metal sectors. The number of 'significant' odds ratios is consistent with an overall 'null-effect'.

Occupational and environmental risk factors for brain cancer: a pilot case-control study in France

INTRODUCTION

The increased incidence of malignant primary brain tumors (MPBT) reported in several studies could be due to environmental factors. To estimate the chemical and physical risk factors of these tumors in southeastern France, a pilot case-control study that included all new MPBT cases diagnosed in 2005 in the main brain cancer treatment centers in the western section of the Provence-Alpes-Côte d'Azur (PACA) region.

MATERIAL AND METHODS

Age-, sex-, and hospital-matched controls were selected from the neurosurgery department of the same hospital. An occupational physician, using a standardized questionnaire, collected information on suspected risk factors of MPBT in a face-to-face interview at the hospital of all case and control subjects. Data collected included jobs held, various exposures throughout working life, and leisure time activities.

RESULTS

The study included 122 cases and 122 controls. No particular job was identified as a major risk factor for brain cancer. Risk was significantly higher among those who used glue (OR=17.58, 95% CI 1.75 - 176.62) during leisure activities and significantly lower among those residing near cellular telephone towers (OR=0.49, 95% CI 0.26 - 0.92).

DISCUSSION

Several new hypotheses about the effects of cellular telephone towers and chemical exposure merit further analytic studies.

Occupational exposure to magnetic fields and the risk of brain tumors

We investigated the association between occupational exposure to extremely low-frequency magnetic fields (MFs) and the risk of glioma and meningioma. Occupational exposure to MF was assessed for 489 glioma cases, 197 meningioma cases, and 799 controls enrolled in a hospital-based case-control study. Lifetime occupational history questionnaires were administered to all subjects; for 24% of jobs, these were supplemented with job-specific questionnaires, or "job modules," to obtain information on the use of electrically powered tools or equipment at work. Job-specific quantitative estimates for exposure to MF in milligauss were assigned using a previously published job exposure matrix (JEM) with modification based on the job modules. Jobs were categorized as < or =1.5 mG, >1.5 to <3.0 mG, and > or =3.0 mG. Four exposure metrics were evaluated: (1) maximum exposed job; (2) total years of exposure >1.5 mG; (3) cumulative lifetime exposure; and (4) average lifetime exposure. Odds ratios (ORs) were calculated using unconditional logistic regression with adjustment for the age, gender, and hospital site. The job modules increased the number of jobs with exposure > or =3.0 mG from 4% to 7% relative to the JEM. No statistically significant elevation in ORs or trends in ORs across exposure categories was observed using four different exposure metrics for the three tumor types analyzed. Occupational exposure to MFs assessed using job modules was not associated with an increase in the risk for glioma, glioblastoma, or meningioma among the subjects evaluated in this study.

Epidemiology of brain tumors

Gliomas account for more than 70% of all brain tumors, and of these, glioblastoma is the most frequent and malignant histologic type (World Health Organization [WHO] grade IV). There is a tendency toward a higher incidence of gliomas in highly developed, industrialized countries. Some reports indicate that Caucasians have a higher incidence than African or Asian populations. With the exception of pilocytic astrocytomas (WHO grade I), the prognosis of glioma patients is still poor. Fewer than 3% of glioblastoma patients are still alive at 5 years after diagnosis, older age being the most significant and consistent prognostic factor of poorer outcome. Gliomas are components of several inherited tumor syndromes, but the prevalence of these syndromes is very low. Many environmental and lifestyle factors including several occupations, environmental carcinogens, and diet have been reported to be associated with an elevated glioma risk, but the only factor unequivocally associated with an increased risk is therapeutic X-irradiation. In particular, children treated with X-irradiation for acute lymphoblastic leukemia show a significantly elevated risk of developing gliomas and primitive neuroectodermal tumors, often within 10 years after therapy. Significant correlation between G:C --> A:T transitions in the TP53 gene and promoter methylation of the O6 -methylguanine-DNA methyltransferase (MGMT) gene in glio-mas have been reported in several studies, suggesting the possible involvement of O6-methylguanine DNA adducts, which may be produced by exogenous or endogenous alkylating agents in the development of gliomas.

Occupational exposure to pesticides and risk of adult brain tumors

The authors examined incident glioma and meningioma risk associated with occupational exposure to insecticides and herbicides in a hospital-based, case-control study of brain cancer. Cases were 462 glioma and 195 meningioma patients diagnosed between 1994 and 1998 in three US hospitals. Controls were 765 patients admitted to the same hospitals for nonmalignant conditions. Occupational histories were collected during personal interviews. Exposure to pesticides was estimated by use of a questionnaire, combined with pesticide measurement data abstracted from published sources. Using logistic regression models, the authors found no association between insecticide and herbicide exposures and risk for glioma and meningioma. There was no association between glioma and exposure to insecticides or herbicides, in men or women. Women who reported ever using herbicides had a significantly increased risk for meningioma compared with women who never used herbicides (odds ratio = 2.4, 95% confidence interval: 1.4, 4.3), and there were significant trends of increasing risk with increasing years of herbicide exposure (p = 0.01) and increasing cumulative exposure (p = 0.01). There was no association between meningioma and herbicide or insecticide exposure among men. These findings highlight the need to go beyond job title to elucidate potential carcinogenic exposures within different occupations.

Meningiomas: causes and risk factors

Meningiomas are among the most common primary intracranial tumors. Although the vast majority of these tumors are considered histologically benign, the incidence of complications can be high. Few studies have investigated the causes and risk factors for meningioma; this review highlights the current state of knowledge. Gaining a better understanding of the origin of this disease is essential so that treatments and outcomes can be improved and prevention strategies can be developed.

Anaplastic astrocytoma in adults

Anaplastic astrocytoma is an uncommon disease in the adult population. Prognosis is influenced by age, symptom duration, mental status and Karnofsky performance status. A truly complete resection, which is a recognized independent prognostic factor, is not possible and recurrence in the surgical cavity is common. Based on randomized data available, chemotherapy has consistently failed to improve the outcome of patients with anaplastic astrocytoma, while a meta-analysis showed a small, but significant improvement in survival favouring the use of chemotherapy. Outside a clinical trial, postoperative radiotherapy (30 x 2 Gy) remains the standard adjuvant therapy for most patients. For elderly patients, the application of treatment is usually based on performance status and neurological function. In recurrent disease, chemotherapy with temozolomide has been proven to be active and well-tolerated in phase II trials, but no comparative phase III trials of other cytotoxic drugs have been conducted.

Environmental risk factors for brain tumors

Primary brain tumors, whether malignant or nonmalignant, have devastating consequences. Unfortunately, few known causes exist. Despite decades of epidemiologic research to identify environmental causes of brain tumors, very little progress has been made. The purpose of this paper is to review the most recent studies in the epidemiology of brain tumors. Popular topics of interest in adult brain tumor epidemiology include electromagnetic fields (particularly cellular phones), occupational exposures, nitroso-containing compounds (especially smoking), hair products, and allergic and immunologic factors. Some of these topics are also applicable to the etiology of childhood brain tumors, but additional areas of interest in the pediatric population focus on parental exposure prior to conception, maternal exposure during pregnancy, and childhood exposure to infectious agents. After an extensive review of the literature since 2001, we present the most relevant studies. Although there are many proposed associations with brain tumors, none possess the statistical significance to confidently ascribe causation. However, new findings and associations, particularly those in allergy and immunology, will present interesting opportunities for further development.

Lead, genetic susceptibility, and risk of adult brain tumors

BACKGROUND

Although few etiologic factors for brain tumors have been identified, limited data suggest that lead may increase the risk of brain tumors, particularly meningioma. The ALAD G177C polymorphism affects the toxicokinetics of lead and may confer genetic susceptibility to adverse effects of lead exposure.

METHODS

We examined occupational exposure to lead and risk of brain tumors in a multisite, hospital-based, case-control study of 489 patients with glioma, 197 with meningioma, and 799 non-cancer controls frequency matched on hospital, age, sex, race/ethnicity, and residential proximity to hospital. ALAD genotype was assessed by a Taqman assay for 355 glioma patients, 151 meningioma patients, and 505 controls. Exposure to lead was estimated using a rigorous questionnaire-based exposure assessment strategy incorporating lead measurement and other occupational data abstracted from published articles and reports.

RESULTS

Increased risk of meningioma with occupational lead exposure (estimated by odds ratios and 95% confidence intervals) was most apparent in individuals with the ALAD2 variant allele, for whom risk increased from 1.1 (0.3-4.5) to 5.6 (0.7-45.5) and 12.8 (1.4-120.8) for estimated cumulative lead exposures of 1 to 49 microg/m3-y, 50 to 99 microg/m3-y, and >or=100 microg/m3-y, respectively, compared with unexposed individuals (two-sided P trend = 0.06). This relationship became stronger after excluding occupational lead exposures characterized by a low confidence level or occurring in the 10 years before meningioma diagnosis. Occupational lead exposure was not associated with glioma risk.

CONCLUSIONS

Although our results indicate that lead may be implicated in meningioma risk in genetically susceptible individuals, these results need to be interpreted with caution given the small numbers of exposed cases with a variant genotype.

Empowerment como forma de prevenção de problemas de saúde em trabalhadores de abatedouros

O objetivo do artigo foi ressaltar a necessidade de esforços educativos que visem ao empowerment de funcionários de abatedouros, baseado nos principais problemas de saúde por eles enfrentados. A rotina em abatedouros consiste em tarefas estressantes e cansativas. As conseqüências incluem problemas músculo-esqueléticos, transmissão de zoonoses, problemas de pele e acidentes com materiais pérfuro-cortantes e animais. Esses trabalhadores geralmente não são especializados, não têm controle sobre suas tarefas, e podem não estar conscientes dos determinantes que afetam sua saúde. Os veterinários são geralmente responsáveis pela rotina de trabalho nesses locais e conhecem os riscos à saúde que a execução dessas tarefas representam. Portanto, esses profissionais poderiam participar mais ativamente na educação para o empowerment dos trabalhadores e não se concentrarem apenas em questões referentes à segurança alimentar.

Agricultural pesticide use and risk of glioma in Nebraska, United States

BACKGROUND

To evaluate the risk of the adult glioma associated with farming and agricultural pesticide use, the authors conducted a population based case control study in eastern Nebraska.

METHODS

Telephone interviews were conducted with men and women diagnosed with gliomas (n = 251) between 1988 and 1993 and controls (n = 498) randomly selected from the same geographical area. Unconditional logistic regression was used to calculate adjusted odds ratios (ORs) for farming and for use of individual and chemical classes of insecticides and herbicides, including pesticides classified as nitrosatable (able to form N-nitroso compounds upon reaction with nitrite). Non-farmers were used as the reference category for all analyses.

RESULTS

Among men, ever living or working on a farm and duration of farming were associated with significantly increased risks of glioma (> or =55 years on a farm OR = 3.9, 95% CI 1.8 to 8.6); however, positive findings were limited to proxy respondents. Among women, there were no positive associations with farming activities among self or proxy respondents. Specific pesticide families and individual pesticides were associated with significantly increased risks among male farmers; however, most of the positive associations were limited to proxy respondents. For two herbicides and three insecticides, use was positively associated with risk among both self and proxy respondents. Based on a small number of exposed cases, ORs were significantly increased for the herbicides metribuzin (OR = 3.4, 95% CI 1.2 to 9.7) and paraquat (OR = 11.1, 95% CI 1.2 to 101), and for the insecticides bufencarb (OR = 18.9, 95% CI 1.9 to 187), chlorpyrifos (OR = 22.6, 95% CI 2.7 to 191), and coumaphos (OR = 5.9, 95% CI 1.1 to 32).

CONCLUSION

The authors found significant associations between some specific agricultural pesticide exposures and the risk of glioma among male farmers but not among female farmers in Nebraska; however, most of the positive associations were limited to proxy respondents. These findings warrant further evaluation in prospective cohort studies where issues of recall bias are not a concern.

Screening of TP53 mutations by DHPLC and sequencing in brain tumours from patients with an occupational exposure to pesticides or organic solvents

The aetiology of brain tumours remains unclear. Occupational exposures to pesticides and organic solvents are suspected risk factors. The case-control study CEREPHY (221 cases, 442 controls) carried in the Departement de la Gironde in France revealed a significantly increased risk of brain tumours for subjects most exposed to pesticides. In some cancers, TP53 mutations could reflect exposure to specific carcinogens. These mutations are present in approximately 30% of astrocytic brain tumours. In a pilot study, we explored the hypothesis that pesticide or solvent exposure could raise the frequency of TP53 mutations in brain tumour cells. We investigated TP53 mutations in exons 2-11 by denaturing high performance liquid chromatography (DHPLC) and sequencing, and p53 accumulation by immunohistochemistry in brain tumour of the 30 patients from CEREPHY study with a history of occupational exposure to pesticides (n = 21) and/or organic solvents (n = 14) for whom tumoral tissue was available. Included cases concerned 27% of CEREPHY cases exposed to pesticides and, based on the cumulative index of occupational exposure, they were more exposed to pesticides. There were 12 gliomas, 6 meningiomas, 7 neurinomas, 2 central nervous system lymphomas and 3 tumours of other histological types. We detected TP53 mutations in three tumours, which is similar to the expected number (3.3) calculated from 46 published studies referenced in the IARC TP53 mutations database, taking into account histological types. Considering TP53 mutations previously detected in the laboratory by DHPLC and the frequency of TP53 polymorphisms detected in this sample (similar to published data), the TP53 mutations rate is probably not underestimated. These preliminary results, even if it was on a limited number of tumours, are not in favour of the role of pesticide or organic solvent exposure in the occurrence of TP53 mutations in brain tumours.

Epidemiology and etiology of gliomas

Gliomas of astrocytic, oligodendroglial and ependymal origin account for more than 70% of all brain tumors. The most frequent (65%) and most malignant histological type is the glioblastoma. Since the introduction of computerized tomography and magnetic resonance imaging, the incidence rates of brain tumors have been rather stable, with a tendency of higher rates in highly developed, industrialized countries. Some reports indicate that Caucasians have higher incidence than black or Asian populations, but to some extent, this may reflect socio-economic differences and under-ascertainment in some regions, rather than a significant difference in genetic susceptibility. With the exception of pilocytic astrocytomas, the prognosis of glioma patients is still poor. Less than 3% of glioblastoma patients are still alive at 5 years after diagnosis, higher age being the most significant predictor of poor outcome. Brain tumors are a component of several inherited tumor syndromes, but the prevalence of these syndromes is very low. Several occupations, environmental carcinogens, and diet (N-nitroso compounds) have been reported to be associated with an elevated glioma risk, but the only environmental factor unequivocally associated with an increased risk of brain tumors, including gliomas, is therapeutic X-irradiation. In particular, children treated with X-irradiation for acute lymphoblastic leukemia show a significantly elevated risk of developing gliomas and primitive neuroectodermal tumor (PNET), often within 10 years after therapy. TP53 mutations are frequent in low-grade gliomas and secondary glioblastomas derived therefrom. Approximately 60% of mutations are located in the hot spot codons 248 and 273, and the majority of these are G:C-->A:T transitions at CpG sites. TP53 mutations are significantly more frequent in low-grade astrocytomas with promoter methylation of the O(6)-methylguanine-DNA methyltransferase repair gene, suggesting that, in addition to deamination of 5-methylcytosine, exogenous or endogenous alkylation in the O(6) position of guanine may contribute to the formation of these mutations.

Occupational risk factors for low grade and high grade glioma: results from an international case control study of adult brain tumours

The majority of suspected occupational risk factors for adult brain tumours have yet to be confirmed as etiologically relevant. Within an international case-control study on brain tumours, lifelong occupational histories and information on exposures to specific substances were obtained by direct interviews to further investigate occupational risk factors for glioma. This is one of the largest studies of brain tumours in adults, including 1,178 cases and 1987 population controls from 8 collaborating study centres matched for age, gender and centre. All occupational information, was aggregated into 16 occupational categories. In a pooled analysis, odds ratios (OR), adjusted for education, were estimated separately for men and women and for high-grade glioma (HGG) and low-grade glioma (LGG), focusing especially on 6 categories defined a priori: agricultural, chemical, construction, metal, electrical/electronic and transport. For men, an elevated OR of glioma associated with the category "metal" (OR = 1.24, 95% CI 0.96-1.62) was seen, which appeared to be largely accounted for by LGG (OR = 1.59, 95% CI 1.00-2.52). For the other 5 occupational categories, no elevated risks for glioma were observed. For women the only noteworthy observation for the 6 a priori categories was an inverse association with the "agriculture" category (OR = 0.60, 95% CI 0.36-0.99). Apart from the 6 major categories, women working in food production or food processing (category "food") showed an increased OR of 1.95 (95% CI 1.04-3.68). None of the 20 substance groups was positively associated with glioma risk. Although some other point estimates were elevated, they lacked statistical significance. The results do not provide evidence of a strong association between occupational exposures and glioma development.

Occupation and risk of meningioma and acoustic neuroma in the United States

BACKGROUND

Workplace exposures may be related to the development of brain tumors. In this case-control study, we examine occupation as a risk factor for meningioma and acoustic neuroma.

METHODS

A lifetime work history was obtained for 197 incident cases of meningioma, 96 cases of acoustic neuroma and 799 controls with non-malignant diseases enrolled from three hospitals in the United States between 1994 and 1998. Jobs considered to have similar tasks and chemical exposures were assigned to an occupational group. Logistic regression was used to estimate odds ratios (OR) adjusted for study matching factors (hospital, age, sex, race/ethnicity, and proximity of residence to the hospital) and education.

RESULTS

Elevated risk of meningioma was observed for individuals who had ever worked in the following occupational groups: auto body painters, designers and decorators, military occupations, industrial production supervisors, teachers, and managers. For acoustic neuroma, increased risk was noted for having worked as an athlete, gas station attendant, purchasing agent, sales representative, or teacher.

CONCLUSIONS

Although limited by multiple comparisons and the relatively small number of cases and controls in many occupational groups, these results nevertheless provide clues that deserve additional study in future epidemiologic studies.