Risk factors for glioma in adults: a case-control study in northeast China

Traumatic Brain Injury and Subsequent Risk of Brain Cancer in US Veterans of the Iraq and Afghanistan Wars

Importance

While brain cancer is rare, it has a very poor prognosis and few established risk factors. To date, epidemiologic work examining the potential association of traumatic brain injury (TBI) with the subsequent risk of brain cancer is conflicting. Further data may be useful.

Objective

To examine whether a history of TBI exposure is associated with the subsequent development of brain cancer.

Design, Setting, and Participants

A retrospective cohort study was conducted from October 1, 2004, to September 20, 2019, and data analysis was performed between January 1 and June 26, 2023. The median follow-up for the cohort was 7.2 (IQR, 4.1-10.1) years. Veterans Affairs (VA) and Department of Defense (DoD) administrative data on 1 919 740 veterans from the Long-Term Impact of Military-Relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium were included.

Exposure

The main exposure of interest was TBI severity (categorized as mild, moderate or severe [moderate/severe], and penetrating).

Main Outcomes and Measures

The outcome of interest was the development of brain cancer based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) or International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnostic codes in either the DoD/VA medical records or from the National Death Index.

Results

After 611 107 exclusions (predominately for no encounter during the study period), a cohort including 1 919 740 veterans was included, most of whom were male (80.25%) and non-Hispanic White (63.11%). Median age at index date was 31 (IQR, 25-42) years. The cohort included 449 880 individuals with TBI (mild, 385 848; moderate/severe, 46 859; and penetrating, 17 173). Brain cancer occurred in 318 individuals without TBI (0.02%), 80 with mild TBI (0.02%), 17 with moderate/severe TBI (0.04%), and 10 or fewer with penetrating TBI (≤0.06%). After adjustment, moderate/severe TBI (adjusted hazard ratio [AHR], 1.90; 95% CI, 1.16-3.12) and penetrating TBI (AHR, 3.33; 95% CI, 1.71-6.49), but not mild TBI (AHR, 1.14; 95% CI, 0.88-1.47), were associated with the subsequent development of brain cancer.

Conclusions and Relevance

In this cohort study of veterans of the Iraq and Afghanistan wars, moderate/severe TBI and penetrating TBI, but not mild TBI, were associated with the subsequent development of brain cancer.

Association of Traumatic Brain Injury and Glioblastoma Multiforme: A Case Series

Glioblastoma multiforme (GBM) is an aggressive variant of central nervous system gliomas that carries a dismal prognosis. Although GBM is the most frequently occurring and malignant type of glioma accounting for more than 60% of all brain tumors in adults, its overall incidence is rare, occurring at a rate of 3.21 per 100,000 persons. Little is known about the etiology of GBM, but one proposed theory is that GBM pathogenesis may be linked to a chronic inflammatory course initiated by traumatic injury to the brain. Limited case reports have suggested an association between GBMs and traumatic brain injury (TBI), but larger case-control and epidemiologic studies have been inconclusive. We present three service members (two active duty and one retired) who developed GBM near the original site of prior head trauma. Each service member's military occupation was in the special operations community and shared a common theme of TBI following head trauma/injury. The current research on the association between TBI and GBM is limited and conflicting, predominantly due to the low incidence of the disease in the general population. Evidence has indicated that TBI should be considered a chronic disease with long-term health impacts, including long-term disability, dementia, epilepsy, mental health conditions, and cardiovascular diseases. With the addition of our patients, as well as a recently published study proposing a molecular association between trauma and GBM, further research is needed to better understand the potential relationship.

Healthy dietary patterns, foods, and risk of glioma: A systematic review and meta-analysis of observational studies

Background

Accumulating epidemiological evidence has shown the favorable associations between healthy dietary patterns and risk of glioma, although the results remain inconclusive.

Objective

We therefore carried out a systematic review and meta-analysis to summarize the evidence from previous published studies, and to clarify the effects of healthy dietary patterns, typical healthy foods on glioma.

Methods

PubMed, Web of Science, CNKI, and Wan fang data were searched from inception up to September 2022 for eligible studies. Two authors independently performed the literature search, study selection, data extraction, and quality assessment. Heterogeneity across studies was estimated using the Cochran's Q test and I ² statistic. According to heterogeneity, the fixed-effects model or random-effects model was selected to obtain the relative risk (RR) of the merger. Subgroup analysis, sensitivity analysis and publication bias were also used for our analysis.

Results

Twenty-four articles that met the selection criteria, involving 7,278 glioma cases and 2,143,528 participants, were included in our analysis. There was a reduced risk of glioma in the highest compared with the lowest categories of healthy dietary patterns (RR = 0.58; 95% CI: 0.44-0.77; P < 0.0001). Moreover, compared with the lowest intakes, the highest intakes of vegetables (RR = 0.84; 95% CI: 0.73-0.96; P = 0.012) and fruits (RR = 0.85; 95% CI: 0.72-1.00; P = 0.045) significantly reduce the risk of glioma. However, the intakes of fresh fish, nuts, whole grains, and dairy products showed no statistically significant associations with the risk of glioma (P > 0.05).

Conclusion

Findings from this systematic review and meta-analysis indicate that higher intakes of healthy dietary patterns, vegetables, and fruits are significantly associated with the lower risk of glioma. Further studies, particularly with prospective design, are required to confirm our findings.

Post-traumatic brain injury glioma: Characteristics, report of 2 cases report and literature review

BACKGROUND

Traumatic brain injury (TBI) as a pathogenetic factor in glioma remains controversial, and currently there is still no clear mechanism behind post-TBI glioma. Thus, we provide two case reports of post-TBI glioma contributing power to this research, and we provide a summary of the mechanisms of post-TBI glioma through literature review.

METHODS

We report two cases of brain gliomas that developed in the scar of a previous brain trauma. Both patients were male and both had suffered prior traumatic brain injuries (time interval 10-20 years), and postoperative pathological findings reported glioblastoma and WHO grade III glioma, respectively.

RESULTS

These two cases further support the association of between traumatic brain injury and gliomas development.

CONCLUSION

Although the epidemiological investigation between TBI and glioma is still controversial, there are still some important aspects here that can determine the possibility between TBI and gliomagenesis. Besides, we found that the reparative response of neural stem cells and the dysregulation of inflammatory cells are timportant theories of the mechanism of post-TBI glioma.

Glioblastoma 20 years after a nail gun trauma: A risk factor?

A 48-year-old man presented with headaches and confusion. Imaging demonstrated a right frontal glioblastoma multiforme (GBM), twenty years after a nail gun injury to the same region. GBM in the same location as a previous injury points toward possible causation from the trauma in the development of a high-grade glioma.

Post-Traumatic Gliomas in Adults: Review of the Case Reports and Studies

Traumatic brain injury (TBI) was first proposed as a potential risk factor for developing a glioma in the 1800s, and conditions for establishing a causal relationship between brain injury and gliomas have since been proposed. Given the medical and legal ramifications, the current literature was reviewed to better understand this possible association. Articles that examined the relationship between TBI and glioma formation in adults and were published in English between 1978 and 2022 were reviewed. There were 19 case reports of 25 patients and 16 observational studies. The case reports describe glioma formation at the precise site of prior brain injury in continuity with traumatic scar; the observational studies report conflicting findings, but they largely demonstrate no association. Most of the observational studies are limited by their retrospective nature, but we identified one prospective cohort study which found a positive association. Altogether, we suggest that glioma formation after TBI is a rare occurrence that warrants further study.

Dietary Factors and Risk of Glioma in Adults: A Systematic Review and Dose-Response Meta-Analysis of Observational Studies

Background

Gliomas are the most common primary intracranial tumors in adults. Inappropriate dietary habits are thought to be a risk factor for most human cancer, and glioma is no exception. However, the effect of dietary factors on glioma is not clear.

Objective

This review aims to quantitatively evaluate the association between various dietary intakes and glioma using a meta-analysis.

Methods

We searched articles on PubMed, the Cochrane Library, the Web of Science, and EMBASE from their inception until October 11, 2021. According to heterogeneity, the fixed-effects or random-effects model was selected to obtain the relative risk (RR) of merger. Based on the methods described by Greenland and Longnecker, we explored the dose-response relationship between dietary intakes and the risk of glioma. Subgroup analysis, sensitivity analysis, and publication bias were also used.

Results

This study reviewed 33 articles, including 3,606,015 controls and 8,831 patients with glioma. This study included 12 food groups. Compared with the lowest intakes, the highest intakes of tea (RR = 0.82, 95%CI:0.71–0.93), total vegetables (RR = 0.84, 95%CI: 0.70–1.00), green vegetables (RR = 0.80, 95%CI: 0.66–0.98), and orange vegetables (RR = 0.79, 95%CI: 0.66–0.96) significantly reduced the risk of glioma, while the highest intakes of grains (RR = 1.39, 95%CI: 1.16–1.66), processed meats (RR = 1.19, 95%CI: 1.00–1.42), and processed fish (RR = 1.37, 95%CI: 1.03–1.84) significantly increased the risk of glioma. The results of subgroup and sensitivity analyses remained unchanged. In the dose-response relationship, only tea was statistically significant. Taking an extra cup of tea every day reduced the risk of glioma by 4%.

Conclusions

Our analysis suggests that the intakes of tea, total vegetables, green vegetables, and orange vegetables may reduce the risk of glioma, while the intakes of grains, processed meats, and processed fish may increase the risk of glioma. Therefore, the effect of dietary factors on glioma should not be ignored.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/, CRD42022296658.

A combined healthy lifestyle score in relation to glioma: a case-control study

Background

The evidence on the association between adherence to a healthy lifestyle and risk of glioma are scarce. This is particularly relevant to Middle Eastern countries where lifestyle factors including dietary intakes, physical activity and environmental contributors are different from other parts of the world. The aim of this case-control study was, therefore, investigating the association between adherence to a healthy lifestyle and odds of glioma among adults.

Methods

Totally, 128 newly diagnosed glioma cases and 256 age- and sex-matched controls were recruited in this hospital-based case-control study. Dietary intakes were examined by the use of a 126-item validated FFQ. International Physical Activity Questionnaire (IPAQ) was used for measuring physical activity of participants. To construct a healthy lifestyle score (HLS), data from dietary intakes, physical activity and BMI were used. Subjects in the low risk categories of the mentioned components received the score of 1, otherwise they received the score of 0. The final HLS was computed through summing up the scores of components.

Results

After adjustment for age and sex, we found that individuals with the highest HLS score were 55% less likely to have glioma compared with those with the lowest score (OR: 0.45; 95% CI: 0.22, 0.92). Additional controlling for other potential confounders made the association stronger (OR: 0.28; 95%CI: 0.12, 0.66). In terms of individual components of healthy lifestyle score, subjects with a healthy diet had 54% lower odds of glioma than those with a non-healthy diet (OR: 0.46; 95%CI: 0.26, 0.80). No significant associations were seen between physical activity level or BMI status and glioma.

Conclusion

We found evidence indicating that adherence to a healthy lifestyle, in particular a healthy diet, was associated with a lower odds of glioma. Prospective cohort studies are needed to confirm these findings.

The Promoting Effect of Traumatic Brain Injury on the Incidence and Progression of Glioma: A Review of Clinical and Experimental Research

The role of traumatic brain injury in the development of glioma is highly controversial since first presented. This is not unexpected because traumatic brain injuries are overwhelmingly more common than glioma. However, the causes of post-traumatic glioma have been long discussed and still warrant further research. In this review, we have presented an overview of previous cohort studies and case–control studies. We have summarized the roles of microglial cells, macrophages, astrocytes, and stem cells in post-traumatic glioma formation and development, and reviewed various carcinogenic factors involved during traumatic brain injury, especially those reported in experimental studies indicating a relationship with glioma progression. Besides, traumatic brain injury and glioma share several common pathways, including inflammation and oxidative stress; however, the exact mechanism underlying this co-occurrence is yet to be discovered. In this review, we have summarized current epidemiological studies, clinical reports, pathophysiological research, as well as investigations evaluating the probable causes of co-occurrence and treatment possibilities. More efforts should be directed toward elucidating the relationship between traumatic brain injury and glioma, which could likely lead to promising pharmacological interventions towards designing therapeutic strategies.

Natural Compounds in Glioblastoma Therapy: Preclinical Insights, Mechanistic Pathways, and Outlook

Simple Summary

Glioblastoma (GBM) is a tumor of the brain or spinal cord with poor clinical prognosis. Current interventions, such as chemotherapy and surgical tumor resection, are constrained by tumor invasion and cancer drug resistance. Dietary natural substances are therefore evaluated for their potential as agents in GBM treatment. Various substances found in fruits, vegetables, and other natural products restrict tumor growth and induce GBM cell death. These preclinical effects are promising but remain constrained by natural substances’ varying pharmacological properties. While many of the reviewed substances are available as over-the-counter supplements, their anti-GBM efficacy should be corroborated by clinical trials moving forward.

Abstract

Glioblastoma (GBM) is an aggressive, often fatal astrocyte-derived tumor of the central nervous system. Conventional medical and surgical interventions have greatly improved survival rates; however, tumor heterogeneity, invasiveness, and chemotherapeutic resistance continue to pose clinical challenges. As such, dietary natural substances—an integral component of the lifestyle medicine approach to chronic diseases—are examined as potential chemotherapeutic agents. These heterogenous substances exert anti-GBM effects by upregulating apoptosis and autophagy, inducing cell cycle arrest, interfering with tumor metabolism, and inhibiting proliferation, neuroinflammation, chemoresistance, angiogenesis, and metastasis. Although these beneficial effects are promising, natural substances’ efficacy in GBM is constrained by their bioavailability and blood–brain barrier permeability; various chemical formulations are proposed to improve their pharmacological properties. Many of the reviewed substances are available as over-the-counter dietary supplements, underscoring their viability as lifestyle interventions. However, clinical trials remain necessary to substantiate the in vitro and in vivo properties of natural substances.

Systematic review of the epidemiology of a single physical trauma and cancer

Background

A systematic review of single physical trauma and cancer was carried out, with a meta-analysis where deemed appropriate.

Methods

A comprehensive search of the literature including databases such as Medline and Embase identified 1529 potentially relevant papers for inclusion. A further 89 potentially relevant studies were identified from bibliographies. After review of titles and abstracts and then full papers, a total of 77 studies were included in the broader review of trauma and cancer, and 31 of these studies considered single physical trauma and cancer. The searches were carried out in June 2016.

Results

Although physical trauma as a cause of cancer has been an issue of clinical interest for decades, the epidemiological evidence was sparse. Only for traumatic brain injury and brain cancer was there considered a sufficient number of epidemiological studies for a meta-analysis. A random effects meta-relative risk for glioma from cohort studies was 0.96 (95% CI: 0.49 to 1.88) and 1.53 (95% CI: 1.02 to 2.27) for case-control studies. The equivalent results for meningioma were 1.22 (95% CI: 0.85 to 1.76) and 1.88 (95% CI: 0.84 to 1.49) respectively.

Conclusions

Further work is required to clarify whether physical trauma has a role in cancer development, perhaps by exploiting trauma registries.

Bayesian Space-Time Analysis of Brain Cancer Incidence in Southern Ontario, Canada: 2010-2013

Canada has one of the highest incidence rates of brain cancer in the world. This study investigates the space–time variation of brain cancer risk across Southern Ontario, Canada. A Bayesian spatio-temporal regression model is used to estimate the relative risk of brain cancer in the 12 spatial health units of Southern Ontario over a four-year period (2010–2013). This work also explores the association between brain cancer and two potential risk factors: traumatic head injury (THI) and excess body fat (EBF). Across all areal units from 2010–2013, results show that the relative risk of brain cancer ranged from 0.83 (95% credible interval (CI) 0.74–0.91) to 1.26 (95% CI 1.13–1.41). Over the years, the eastern and western health units had persistently higher risk levels compared to those in the central areas. Results suggest that areas with elevated THI rates and EBF levels were also potentially associated with higher brain cancer relative risk. Findings revealed that the mean temporal trend for cancer risk progression in the region smoothly decreased over time. Overall, 50% of the health units displayed area-specific trends which were higher than the region’s average, thus indicating a slower decrease in cancer rates for these areas in comparison to the mean trend.

The Pathophysiology of Post-Traumatic Glioma

Malignant glioma is a brain tumor with a very high mortality rate resulting from the specific morphology of its infiltrative growth and poor early detection rates. The causes of one of its very specific types, i.e., post-traumatic glioma, have been discussed for many years, with some studies providing evidence for mechanisms where the reaction to an injury may in some cases lead to the onset of carcinogenesis in the brain. In this review of the available literature, we discuss the consequences of breaking the blood–brain barrier and consequences of the influx of immune-system cells to the site of injury. We also analyze the influence of inflammatory mediators on the expression of genes controlling the process of apoptosis and the effect of chemical mutagenic factors on glial cells in the brain. We present the results of experimental studies indicating a relationship between injury and glioma development. However, epidemiological studies on post-traumatic glioma, of which only a few confirm the conclusions of experimental research, indicate that any potential relationship between injury and glioma, if any, is indirect.

Prenatal and Postnatal Medical Conditions and the Risk of Brain Tumors in Children and Adolescents: An International Multicenter Case-Control Study

BACKGROUND

Previous studies have evaluated the effect of medical diagnostic radiation on brain tumors. Recent cohort studies have reported an increased risk associated with exposure to head CT scans.

METHODS

Information regarding medical conditions, including prenatal and postnatal exposure to medical diagnostic radiation, was obtained from CEFALO, a multicenter case-control study performed in Denmark, Norway, Sweden, and Switzerland through face-to-face interview. Eligible cases of childhood and adolescent brain tumors (CABT) were ages 7 to 19 years, diagnosed between January 1, 2004 and August 31, 2008, and living in the participating countries (n = 352). The cases were matched by age, sex, and region to 646 population-based controls.

RESULTS

Prenatal exposure to medical diagnostic radiation and postnatal exposure to X-rays were not associated with CABTs. A higher risk estimate of CABTs, although not statistically significant, was found for exposure to head CT scan (OR, 1.86; 95% confidence interval, 0.82-4.22). The associations with head injury, febrile seizure, fever in the first 12 weeks, and general anesthesia were close to unity.

CONCLUSIONS

Prenatal or postnatal medical conditions, including medical diagnostic radiation, were not associated with CABTs. On the basis of small numbers of exposed children, we observed a nonsignificant increased risk for CT scans of the head.

IMPACT

We have presented additional evidence, suggesting that exposure to head CT scan may be associated with the occurrence of CABTs. Cancer Epidemiol Biomarkers Prev; 26(1); 110-5. ©2016 AACR.

Cigarette smoking and risk of adult glioma: a meta-analysis of 24 observational studies involving more than 2.3 million individuals

Background

Cigarette smoking has been shown to be a risk factor for adult glioma by some but not all studies. We conducted a meta-analysis to systematically assess the potential association.

Methods

PubMed and EMBASE were searched from the date of their inception to October 1, 2015, to identify relevant articles. Reference lists from these articles were reviewed to identify additional studies. Both cohort and case–control studies were included. Fixed-effects models were used to calculate the overall relative risk (RR) with corresponding 95% confidence intervals (CIs).

Results

The final analysis included 24 studies (seven cohort and 17 case–control studies), involving more than 2.3 million individuals. The combined RR was 1.04 (95% CI: 1.00, 1.09; P=0.073) for ever-smokers, 0.97 (95% CI: 0.88, 1.07; P=0.574) for current-smokers, and 1.07 (95% CI: 0.98, 1.16; P=0.130) for past smokers, with little evidence of heterogeneity. Omission of any single study from the analysis had little effect on the result. No evidence of publication bias was found. A small but statistically significant increase was found in past smokers in females (RR: 1.13, 95% CI: 1.00, 1.28; P=0.046) but not in males.

Conclusion

In general, there was no association between cigarette smoking and adult glioma. The small but statistically significant association in females requires further investigation.

De novo glioblastoma in the territory of a recent middle cerebral artery infarction and a residual meningioma: pathogenesis revisited

Background

The pathogenesis of glioblastoma is complex, and the implicated molecular mechanisms are yet to be understood. There are scattered reports describing a possible relationship between meningioma and glioblastoma and more rarely a relationship between infarction and glioblastoma.

Case presentation

We are reporting a 32-year-old male who developed left middle cerebral artery (MCA) infarction as a surgical complication for sphenoid meningioma. He developed recurrent symptoms 4 months later due to development of a glioblastoma adjacent to both the territory of the prior MCA infarct and the residual meningioma.

Conclusions

This case adds further contribution to the literature of the possible pathological association between glioblastoma and brain infarction on a background of meningioma.

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.

Smoking and Glioma Risk: Evidence From a Meta-Analysis of 25 Observational Studies

To systematically assess the relationship between smoking and glioma risk.A dose-response meta-analysis of case-control and cohort studies was performed. Pertinent studies were identified by searching database and reference lists. Random-effects model was employed to pool the estimates of the relative risks (RRs) with corresponding 95% confidence intervals (CIs).A total of 19 case-control and 6 cohort studies were included. Overall, compared with those who never smoked, the pooled RR and 95% CI was 0.98 (0.92-1.05) for ever smoker. The subgroups were not significantly different regarding risk of glioma except the group of age at start smoking (RR = 1.17, 95% CI: 0.93-1.48 for age < 20; RR = 1.25, 95% CI: 1.02-1.52 for age ≥ 20). Dose-response analysis also suggested no significant association between smoking and the risk of glioma, although some evidence for a linear relationship between smoking and glioma risk was observed.In conclusion, this meta-analysis provides little support for a causal relationship between smoking and risk of glioma.

Red and processed meat consumption and risk of glioma in adults: A systematic review and meta-analysis of observational studies

BACKGROUND

These findings from several observational studies, investigated the association between red meat consumption and gliomas, were inconsistent. We conducted a systematic review and meta-analysis of observational studies to summarize available date on the relation between meat intake and risk of glioma.

MATERIALS AND METHODS

A systematic literature search of relevant reports published until May 2014 of the PubMed/Medline, ISI Web of Knowledge, Excerpta Medica database, Ovid database, Google Scholar, and Scopus databases was conducted. From 723 articles yielded in the preliminary literature search, data from eighteen publications (14 case-control, three cohort, and one nested case-control study) on unprocessed red meat, processed meat, and/or total red meat consumption in relation to glioma in adults were included in the analysis. Quality assessment of studies was performed. Random effects model was used to conduct the meta-analysis.

RESULTS

We found a positive significant association between unprocessed red meat intake and risk of glioma (relative risk [RR] = 1.30; 95% confidence interval [CI]: 1.08-1.58) after excluding three studies with uncertain type of brain cancer. This analysis included only one cohort study which revealed no relation between unprocessed red meat intake and glioma (RR = 1.75; 95% CI: 0.35-8.77). Consumption of processed meats was not related to increased risk of glioma in population-based case-control studies (RR = 1.26; 95% CI: 1.05-1.51) and reduced risk in hospital-based case-controls (RR = 0.79; 95% CI: 0.65-0.97). No significant association was seen between processed red meat intake and risk of glioma in cohort studies (RR: 1.08; 95% CI: 0.84-1.37). Total red meat consumption was not associated with risk of adult glioma in case-control or cohort studies.

CONCLUSION

In this meta-analysis of 18 observational studies, we found a modest positive association between unprocessed red meat intake and risk of gliomas based almost entirely on case-control studies. Processed red meat was overall not associated with risk of gliomas in case-control or cohort studies.

Smoking and adult glioma: a population-based case-control study in China

BACKGROUND

Smoking increases the risk of numerous cancers; however, an association of smoking with adult gliomas has not been found in a population.

METHODS

This case-control study included 4556 glioma cases (ICD-9 code 191.0-191.9) aged ≥ 30 years and 9112 controls from a national survey of smoking and mortality in China in 1989-1991. Controls from 325 255 surviving spouses of all-cause deaths were randomly assigned to cases in each of 103 areas according to sex and age groups at a ratio of 2:1. Smoking information was ascertained retrospectively by interviewing surviving spouses.

RESULTS

After adjustment for confounders, smoking increased the risk of glioma deaths by 11% (odds ratio [OR] = 1.11; 95% confidence interval [CI]: 1.03-1.21). Compared with non-smokers; the increased risk was 9% (OR = 1.09; 95% CI: 0.99-1.20) in men and 16% (OR = 1.16; 95% CI: 1.00-1.36) in women. The risk increased with age and doses. For individuals aged ≥ 50 years, smoking was associated with higher risk of glioma death by 25% (OR = 1.25; 95% CI: 1.15-1.38); this increased risk for smokers who smoked ≥ 20 cigarettes daily for ≥ 30 years was 53% (OR = 1.53; 95% CI: 1.34-1.74). There were similar findings in both men and women and with either pathology-based or non-pathology-based comparisons.

CONCLUSIONS

This study indicates that smoking is associated with glioma deaths in the Chinese population. Long-term heavy smoking could be a factor for risk stratification in individuals attending brain tumor clinics.

Are Risks From Medical Imaging Still too Small to Be Observed or Nonexistent?

Several radiation-related professional societies have concluded that carcinogenic risks associated with doses below 50-100 mSv are either too small to be detected, or are nonexistent. This is especially important in the context of doses from medical imaging. Radiation exposure to the public from medical imaging procedures is rising around the world, primarily due to increased utilization of computed tomography. Professional societies and advisory bodies consistently recommend against multiplying small doses by large populations to predict excess radiation-induced cancers, in large part because of the potential for sensational claims of health impacts which do not adequately take the associated uncertainties into account. Nonetheless, numerous articles have predicted thousands of future cancers as a result of CT scanning, and this has generated considerable concern among patients and parents. In addition, some authors claim that we now have direct epidemiological evidence of carcinogenic risks from medical imaging. This paper critically examines such claims, and concludes that the evidence cited does not provide direct evidence of low-dose carcinogenicity. These claims themselves have adverse public health impacts by frightening the public away from medically justified exams. It is time for the medical and scientific communities to be more assertive in responding to sensational claims of health risks.

The long-term risk of malignant astrocytic tumors after structural brain injury--a nationwide cohort study

BACKGROUND

Neoplastic transformation of damaged astrocytes has been proposed as a possible pathological mechanism behind malignant astrocytic tumors. This study investigated the association between structural brain injuries causing reactive astrogliosis and long-term risk for malignant astrocytic tumors.

METHODS

The cohort consisted of all individuals living in Denmark between 1978 and 2011. The personal identification number assigned to all individuals allowed retrieval of diagnoses of traumatic brain injury, cerebral ischemic infarction, and intracerebral hemorrhage from the National Patient Discharge Register. Diagnoses of anaplastic astrocytoma and glioblastoma multiforme (World Health Organization grades III and IV) were retrieved from the Danish Cancer Registry. Rate ratios (RR's) were estimated using log-linear Poisson regression.

RESULTS

In a cohort of 8.2 million individuals, 404 812 experienced a structural brain injury and 6152 developed a malignant astrocytic tumor. No significant association was observed 1-4 years after a structural brain injury (RR = 1.14; 95% CI: 0.87-1.46), whereas the long-term (5+ y) risk for malignant astrocytic tumors was significantly reduced (RR = 0.68; 95% CI: 0.49-0.90) compared with no injury. The specific long-term risks by type of injury were: traumatic brain injury RR = 0.32 (95% CI: 0.10-0.75); cerebral ischemic infarction RR = 0.69 (95% CI: 0.47-0.96); and intracerebral hemorrhage RR = 1.39 (95% CI: 0.64-2.60).

CONCLUSION

We found no evidence for an association between structural brain injury and malignant astrocytic tumors within the first 5 years of follow-up. However, our study indicated a protective effect of astrogliosis-causing injuries 5 or more years after structural brain injury.

Post-traumatic malignant glioma in a pregnant woman: case report and review of the literature

To add a further contribution to the literature supporting the relationship between previous head trauma and the development of glioma. We present the first case of pregnancy-related post-traumatic malignant glioma in a 29-year-old female who was admitted because of left sided hemiplegia and epilepsy due to a malignant glial tumor. She had been operated for a right frontal hematoma caused by a motorbike accident 9 years before. Neuroimaging showed a large neoplasia in the right frontal region beneath the material used for cranialplasty, and postoperative pathological revealed a glioblastoma multiforme (GBM) in continuity with the scar resulting from the trauma. While epidemiologic studies may not be conclusive, a pathologic basis has been suggested which show that trauma act as a cocarcinogen in the presence of an initiating carcinogen. Our case fulfilled the widely established criteria for brain tumors of traumatic origin. We believe that in specific cases it is reasonable to acknowledge an etiological association between head trauma and glioma. And additional factors such as pregnancy may promote the manifestation of the clinical symptoms.

Association between fruit and vegetable intake and risk for glioma: a meta-analysis

OBJECTIVE

Epidemiologic studies evaluating the association between the intake of vegetables and fruit and the risk for glioma have produced inconsistent results. Therefore, the aim of this study was to test the hypothesis that higher vegetable and fruit intake may have a protective effect on risk for glioma.

METHODS

Pertinent studies were identified by a search in PubMed, Web of Knowledge, and Wan Fang Med Online up to January 2014. Random-effect model was used to combine study-specific results. Publication bias was estimated using Begg's funnel plot and Egger's regression asymmetry test.

RESULTS

Fifteen studies involving 5562 cases focusing on vegetable intake and 17 studies involving 3994 cases of fruit intake compared with the risk for glioma were included in this meta-analysis. The combined relative risk (RR) of glioma associated with vegetable intake was 0.775 (95% confidence interval [CI], 0.688-0.872) overall, and the association for subgroup analysis by study design, sources of control, ethnicity, and number of cases was consistent with overall data. For fruit intake and glioma risk, significant protective associations were found in an Asian population (RR, 0.573; 95% CI, 0.346-0.947), but not in a white population. No publication bias was found.

CONCLUSIONS

This analysis indicated that intake of vegetables might have a protective effect on glioma. The intake of fruit might have a protective effect on glioma in the Asian population; however, the results need to be confirmed.

Alcohol consumption and risk of glioma: a meta-analysis of 19 observational studies

The relationship between risk of glioma and alcohol consumption has been widely studied, but results have been conflicting. We therefore conducted a meta-analysis of observational studies to systematically assess the relationship between alcohol drinking and risk of glioma. Two electronic databases (PubMed and EMBASE) were searched from inception to 8 August 2013 to identify pertinent studies that linked alcohol drinking with glioma risk. We used a random-effects model to calculate the overall relative risk (RR) with corresponding 95% confidence intervals (CIs). Fifteen case-control and four cohort studies were identified for this analysis. The combined RR for total alcohol drinkers versus non-drinkers was 0.96 (95% CI: 0.89–1.04). In the subgroup analysis by geographic area, a significant association was observed in North American studies (RR = 0.78, 95% CI: 0.65–0.93), but not in European or Asian/Australian studies. In the subgroup analysis by study design, a borderline significant association emerged in population-based case-control studies (RR = 0.82, 95% CI: 0.68–0.99), but not in hospital-based case-control studies (RR = 1.00, 95% CI: 0.99–1.01) or cohort group (RR = 1.03, 95% CI: 0.88–1.20). Our results show no material association between alcohol consumption and risk of glioma existed. Further prospective evidences are needed to confirm this association.

Cigarette smoking, alcohol intake, and risk of glioma in the NIH-AARP Diet and Health Study

BACKGROUND

Although cigarette smoking and alcohol drinking increase the risk of several cancers and certain components of cigarette smoke and alcohol can penetrate the blood-brain barrier, it remains unclear whether these exposures influence the risk of glioma.

METHODS

We examined the associations between cigarette smoking, alcohol intake, and risk of glioma in the National Institutes of Health-AARP Diet and Health Study, a prospective study of 477,095 US men and women ages 50-71 years at baseline. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using models with age as the time metric and adjusted for sex, race/ethnicity, education, and marital status.

RESULTS

During a median 10.5 person-years of follow-up, 492 men and 212 women were diagnosed with first primary glioma. Among men, current, heavier smoking was associated with a reduced risk of glioma compared with never smoking, but this was based on only nine cases. No associations were observed between smoking behaviours and glioma risk in women. Greater alcohol consumption was associated with a decreased risk of glioma, particularly among men (>2 drinks per day vs <1 drink per week: HR=0.67, 95% CI=0.51-0.90).

CONCLUSION

Smoking and alcohol drinking do not appear to increase the risk of glioma.

A meta-analysis of alcohol consumption and the risk of brain tumours

BACKGROUND

Alcohol is capable of traversing the blood-brain barrier and is thus a possible risk factor for brain cancer. Several epidemiological studies have been published on the issue, a number of those during recent years, with inconsistent findings.

MATERIALS AND METHODS

We performed a systematic literature search in the Medline and EMBASE databases. We found a total of 19 studies providing risk estimates for total alcohol or specific alcoholic beverages. Pooled estimates of the relative risks (RR) and 95% confidence intervals (CI) were calculated using random-effects models.

RESULTS

The pooled RR of brain cancer for alcohol drinkers versus non-drinkers was 0.97 (95% CI 0.82-1.15; based on 12 studies). Moderate (<2 drinks/day) and heavy alcohol drinkers had RRs of 1.01 (95% CI 0.81-1.25) and 1.35 (95% CI 0.85-2.15), respectively. With reference to specific alcoholic beverages, the RRs were 1.01 (95% CI 0.70-1.48) for wine, 0.96 (95% CI 0.82-1.12) for beer, and 1.20 (95% CI 1.01-1.42) for spirit consumption. The RRs for drinkers versus non-drinkers were 0.93 (95% CI 0.81-1.07) for glioma and 0.71 (95% CI 0.45-1.12) for meningioma.

CONCLUSIONS

Alcohol drinking does not appear to be associated with adult brain cancer, though a potential effect of high doses deserves further study.

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.

Association between traumatic brain injury and the subsequent risk of brain cancer

This population-based study in Taiwan aimed to investigate the risk of having a diagnosis of malignant brain tumors within 3 years after a traumatic brain injury (TBI). This study used data from the Traumatic Brain Injury Registry and the National Health Insurance Research Database. The study cohort comprised 5007 patients who had visited ambulatory care centers or had been hospitalized with a diagnosis of TBI between 2001 and 2002. The comparison cohort was 25,035 randomly selected enrollees. Each patient's brain cancer status was individually tracked for a 3-year period following their index date. Stratified Cox proportional hazards regressions were performed for analyses. During the 3 years of follow-up, nine patients in each cohort, both the TBI and the non-TBI cohort, were diagnosed with brain cancer. As compared to those patients without TBI, patients with TBI were more likely to receive a diagnosis of malignant brain tumors within the 3-year period following their index date: the incidence rate of malignant brain tumors was 6.28 (95% CI: 3.06-11.53) per 10,000 person-years in patients with TBI and 1.25 (95% CI: 0.61-2.29) per 10,000 person-years in patients without TBI. After adjusting for sociodemographic characteristics, the hazard of being diagnosed with malignant brain tumors during the 3-year follow-up period was 4.67 (95% CI: 1.84-11.83) times greater for those who sustained a TBI than for patients in the comparison cohort. In addition, we found an association between TBI severity and malignant brain tumor among patients with TBI (p=0.033). Our findings suggest a positive correlation between TBI and the relatively short-term development of malignant neoplasms of the brain.

Medical diagnostic radiation exposures and risk of gliomas

High-dose ionizing radiation is an established risk factor for glioma, but it remains unknown whether moderate- and low-dose radiation increase glioma risk. In this analysis, we assessed the evidence that self-reported exposures to diagnostic ionizing radiation, including computerized tomography (CT) scans, is associated with increased risk of adult glioma. While no independent association was observed for CT scans alone (3+ scans compared to none P = 0.08 and 1-2 scans compared to none P = 0.68), our findings suggest an increased risk of adult gliomas with cumulative exposure to three or more CT scans to the head and neck region (OR = 1.97, 95% CI: 0.92-4.23) limited to those who reported a family history of cancer: the P value for the interaction between having three or more CT scans and family history of cancer was 0.08. The stratum-specific adjusted OR for those with family history of cancer was more than three times that for the sub-group without family history of cancer. While there is some potential for symptom-related bias, one might expect this to be present for all diagnostic procedures rather than specific to one procedure. The interaction between CT scans and glioma with family history of cancer supports the biological plausibility of our findings, because similar results have been found for breast cancer and radiation. This observational data will increase awareness about potential risks associated with CT scans and the need to minimize the use of unnecessary examinations.

Links between private habits, psychological stress and brain cancer: a case-control pilot study in France

Numerous studies have increasingly suggested that medical history and lifestyle factors could be involved in the increase of cancer risk in adults. The issue whether psychological factors can influence the development of cancer has been discussed for many years. In the field of brain cancer, psychological stress has not so far been investigated. We conducted a French case-control pilot study with 122 adult incident cases and 122 controls free of any cancer diagnosis, matched for age and gender, to investigate links between malignant primitive brain tumours (MPBT) and medical history, private habits and psychological stress. Data were collected through self-administered questionnaires, and person-to-person interviews. To complete the psychological stress assessment, 100-mm visual analog scales were used. After adjustment for confounders, we found no significant effect of head trauma, aspartame, tobacco or alcohol consumption, place (rural or urban) of residence, sociodemographic data, and experience of psychological stress at work/home. Our results showed a significant association between MPBT risk and major life events over the past 5 years before diagnosis (OR = 1.90, 95% CI 1.13-3.20), family histories of cancer (OR = 1.90, 95% CI 1.12-3.22), fresh vegetable and fruit intake (OR = 0.29, 95% CI 0.09-0.95), and skipped meals several times per week (OR = 0.35, 95% CI 0.16-0.77). The present study suggests the role of genetic factors in glioma risk, and also suggests that an acute and sudden psychological stress might influence MPBT appearance. Additional large clinical studies are needed to confirm these findings.

Lead exposure, polymorphisms in genes related to oxidative stress, and risk of adult brain tumors

There is some evidence that oxidative stress plays a role in lead-induced toxicity. Mechanisms for dealing with oxidative stress may be of particular relevance in the brain given the high rate of oxygen metabolism. Using a hospital-based case-control study, we investigated the role of oxidative stress in the potential carcinogenicity of lead through examination of effect modification of the association between occupational lead exposure and brain tumors by single nucleotide polymorphisms in genes with functions related to oxidative stress. The study included 362 patients with glioma (176 of which had glioblastoma multiforme), 134 patients with meningioma, and 494 controls. Lead exposure was estimated by expert review of detailed job history data for each participant. We evaluated effect modification with 142 single nucleotide polymorphisms using likelihood ratio tests that compared nested unconditional logistic regression models that did and did not include a cross-product term for cumulative lead exposure and genotype. When the analyses were restricted to cases with glioblastoma multiforme, RAC2 rs2239774 and two highly correlated GPX1 polymorphisms (rs1050450 and rs18006688) were found to significantly modify the association with lead exposure (P Collapse

Key Words

• glioma
• meningioma
• lead exposure
• oxidative stress
• polymorphism

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MESH Headings

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Brain Neoplasms/chemically induced
• Brain Neoplasms/genetics
• Female
• Genetic Predisposition to Disease
• Glutathione Peroxidase/genetics
• Humans
• Lead/adverse effects
• Male
• Middle Aged
• Occupational Diseases/genetics
• Occupational Exposure/adverse effects
• Oxidative Stress/genetics
• Polymerase Chain Reaction
• Polymorphism, Single Nucleotide
• Risk Factors
• Young Adult
• rac GTP-Binding Proteins/genetics
• Glutathione Peroxidase GPX1
• RAC2 GTP-Binding Protein

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Grants

• N01CO12400 NCI NIH HHS
• NIH0011946573 Intramural NIH HHS
• Z01 CP010135-12 Intramural NIH HHS
• N01-CO-12400 NCI NIH HHS

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Affiliation(s)

Parveen Bhatti Department of Health ad Human Services, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Bethesda, Maryland, USA.
Patricia A Stewart
Amy Hutchinson
Nathaniel Rothman
Martha S Linet
Peter D Inskip
Preetha Rajaraman

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Dietary prevention of malignant glioma aggressiveness, implications in oxidant stress and apoptosis

Our study explored the influence of diet on gliomagenesis and associated systemic effects (SE) in rats. The experimental diet contained various ingredients supposed to interfere with carcinogenesis, mainly phytochemicals (PtcD for phytochemical diet) and its effects were compared to those of the same diet without the phytochemicals (BD for basal diet). Glioma was induced by ethylnitrosourea to pregnant females fed the diets from the start of gestation until the moment of sacrifice of the offpsrings. In male rats fed the PtcD or the BD the incidence of gliomas was markedly reduced compared to rats fed a standard diet (StD). In females this effect was weaker and was limited to the PtcD. A significant proportion of rats with brain tumors and fed the StD exhibited SE evidenced by weight loss, a shorter survival, reduction in liver weight and an increased proportion of liver mitochondria, effects that were not observed in their counterpart fed PtcD. Comparison of the expression of genes involved in the balance proliferation/apoptosis and in the response to oxidative stress in male brain tumors showed that the prevention of SE was associated with an increase in bcl-2 and catalase and a decrease in ki-67, sod-1 and sod-2 transcripts. These results show that the degree of agressiveness of gliomas can be modulated by dietary interventions and suggest that some phytochemicals with antioxidant properties could participate to the mechanism.

Epidemiology of brain tumors

Brain tumors seemed to have increased in incidence over the past 30 years, but the rise probably results from use of new neuroimaging techniques. Treatments have not improved prognosis for rapidly fatal brain tumors. Established brain tumor risk factors (exposure to ionizing radiation, rare mutations of penetrant genes, and familial history) explain only a small proportion of brain tumors, and only one of these potentially is modifiable. Genetic and environmental characteristics likely play a role in familial aggregation of glioma and these factors are not identified. New concepts in brain tumor etiology and clinical management are the goal of research, with an aim at eradicating this devastating disease.

Prospective study of cigarette smoking and adult glioma: dosage, duration, and latency

Tobacco products are major contributors of exogenous N-nitroso compounds, a group of potent neurocarcinogens. Overall results from studies of smoking and brain tumors have been null, but have provided little information on duration, age at smoking initiation, and latency. We prospectively examined the relation between cigarette smoking and glioma risk among men and women in three large U.S. cohort studies: the Health Professionals Follow-up Study (HPFS), the Nurses' Health Study I (NHS), and NHS II. Information on smoking history was obtained at baseline (1986 for HPFS, 1976 for NHS, and 1989 for NHS II) and updated biennially through 2002 in the HPFS and the NHS and 2003 in the NHS II. We confirmed 110 incident gliomas among men and 255 gliomas among women during 667,673 and 4,388,515 person-years of follow-up, respectively. Cox proportional hazard models were used to estimate incidence rate ratios and 95% confidence intervals between smoking and glioma risk adjusting for age, total meat intake, and alcohol and coffee consumption. Estimates from each cohort were pooled using a random-effects model after determining that there was no heterogeneity by sex. No association with glioma risk was observed between baseline or updated smoking status, intensity, duration, or age at smoking initiation among men and women. Furthermore, no association with glioma risk was observed after allowing for an induction period between smoking and glioma diagnosis. These findings provide strong evidence that cigarette smoking is not associated with an appreciably elevated risk of adult glioma.

Prospective study of intake of fruit, vegetables, and carotenoids and the risk of adult glioma

BACKGROUND

Nutrients in dietary fruit and vegetables have been hypothesized to lower the risk of glioma by reducing the endogenous formation of N-nitroso compounds. Studies examining fruit and vegetable consumption and brain tumors have relied on case-control study designs, with one exception, and results have been inconsistent.

OBJECTIVE

We prospectively examined the relation between consumption of fruit and vegetables (and specifically carotenoids) and the risk of glioma among men and women in 3 large US cohort studies: the Health Professionals Follow-Up Study (HPFS), the Nurses' Health Study I (NHS I), and NHS II.

DESIGN

Dietary intake was assessed by food-frequency questionnaires obtained at baseline and updated every 4 y through 2002 (HPFS and NHS I) or 2003 (NHS II). We identified 296 incident adult gliomas during 3 669 589 person-years of follow-up. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% CIs between intake of fruit, vegetables, and carotenoids and glioma risk, with adjustment for age and total caloric intake.

RESULTS

Updated average consumption of total fruit and vegetables was not significantly associated with glioma risk in the men and women (pooled multivariate RR in a comparison of the highest with the lowest quintile: 1.12; 95% CI: 0.74, 1.69). Other fruit and vegetable subgroups, individual fruit and vegetables, and 5 major carotenoids were not significantly associated with risk of glioma.

CONCLUSION

Our findings suggest that fruit, vegetable, and carotenoid consumption is not likely associated strongly with the risk of adult glioma.

Fruit and vegetables in cancer prevention

Our aim was to review the epidemiological literature on possible cancer-preventive effects of the consumption of fruits and vegetables in humans, to quantify the effect of high versus low consumption of fruits and vegetables, and to give an overall assessment of the existing evidence. We based our work on an expert meeting conducted by the International Agency for Research on Cancer in 2003. A qualitative reading and evaluation of relevant articles on the cancer-preventive effect of the consumption of fruits and vegetables was made followed by the calculation of the mean relative risk and range for cohort and case-control studies separately. The possible population-preventable fraction for modifying diet in relation to fruit and vegetable consumption was calculated as well as an overall statement about the degree of evidence for the cancer-preventive effect of fruit and vegetable consumption for each cancer site. There is limited evidence for a cancer-preventive effect of the consumption of fruits and vegetables for cancer of the mouth and pharynx, esophagus, stomach, colon-rectum, larynx, lung, ovary (vegetables only), bladder (fruit only), and kidney. There is inadequate evidence for a cancer-preventive effect of the consumption of fruits and vegetables for all other sites. Applying this range of risk difference to the range of prevalence of low intake, the preventable fraction for low fruit and vegetable intake would fall into the range of 5-12%. It is important to recognize that this is only a crude range of estimates and that the proportion of cancers that might be preventable by increasing fruit and vegetable intake may vary beyond this range for specific cancer sites and across different regions of the world.

Brain cancer mortality and potential occupational exposure to lead: findings from the National Longitudinal Mortality Study, 1979-1989

We evaluated the association between potential occupational lead exposure and the risk of brain cancer mortality in the National Longitudinal Mortality Study (NLMS), which is a prospective census-based cohort study of mortality among the noninstitutionalized United States population (1979-1989). The present study was limited to individuals for whom occupation and industry were available (n = 317,968). Estimates of probability and intensity of lead exposure were assigned using a job-exposure matrix (JEM). Risk estimates for the impact of lead on brain cancer mortality were computed using standardized mortality ratio (SMR) and proportional hazards and Poisson regression techniques, adjusting for the effects of age, gender and several other covariates. Brain cancer mortality rates were greater among individuals in jobs potentially involving lead exposure as compared to those unexposed (age- and gender-adjusted hazard ratio (HR) = 1.5; 95% confidence interval (CI) = 0.9-2.3) with indications of an exposure-response trend (probability: low HR = 0.7 (95% CI = 0.2-2.2), medium HR = 1.4 (95% CI = 0.8-2.5), high HR = 2.2 (95% CI = 1.2-4.0); intensity: low HR = 1.2 (95% CI = 0.7-2.1), medium/high HR = 1.9 (95% CI = 1.0-3.4)). Brain cancer risk was greatest among individuals with the highest levels of probability and intensity (HR = 2.3; 95% CI = 1.3-4.2). These findings provide further support for an association between occupational lead exposure and brain cancer mortality, but need to be interpreted cautiously due to the consideration of brain cancer as one disease entity and the absence of biological measures of lead exposure.

Chronic malnutrition does not influence the development of ethylnitrosourea-induced brain tumors

There is controversy over the subject of malnutrition as a potential risk factor for cancer; we studied the effect of chronic malnutrition on the development of tumors in rats prenatally exposed to the carcinogenic ethylnitrosourea. Twelve pregnant Wistar rats were administered on the 19th day of gestation with a single i.v. dose of 30 mg/kg of ethylnitrosourea. Immediately after weaning, at 23 days of age, half of the offspring were nourished with a protein-deficient diet (less than 6%), which consisted mostly of a corn-based diet with high calorie and low fiber contents. In the adult age, 83 rats (74%) developed a tumor of the nervous system; in comparison with controls, we found no differences in time of development, site and histological characteristics of the tumors that developed in animals subjected to chronic malnutrition.

Head injury and brain tumours in adults: A case–control study in Rio de Janeiro, Brazil

A hospital-based case-control study exploring the association between selected risk factors and head injury in adults, brain trauma included, was carried out in Greater Metropolitan Rio de Janeiro, Brazil. Cases included adults diagnosed with primary brain tumours (n = 231). Controls were matched for gender and age among in-patients hospitalized for various conditions unrelated to brain cancer (n = 261) identified in the same hospitals where cases were enrolled. Risk of having experienced head injury was more frequent among cases (46%) than controls (36%) (OR(adj) = 1.49; 95% CI = 1.03-2.15). A dose-response effect was observed according to the number of head injuries, and a statistically borderline association was observed for meningioma (OR(adj) = 1.63; 95% CI = 0.96-2.75). Although recall bias cannot be ruled out, our results suggest an association between prior head injury and the development of brain tumours in adults.

Predisposing conditions and risk factors for development of symptomatic meningioma in adults

BACKGROUND

Risk factors and predisposing factors for the development of symptomatic meningioma during adult life are not well known.

METHODS

Data from 306 consecutive patients with primary meningioma were collected retrospectively in a hypothesis-generating study. Factors studied included localisation of tumours, blood group typing, and risk factors, such as diabetes mellitus, coronary arterial disease, hypertension, rheumatoid arthritis, bronchial asthma, smoking, obesity, and second primary tumour. Case-control analysis of putative risk factors was carried out using a control data set from the German East-West Health Survey (n=7466, age range 25-69 years). Patients and controls were matched for age, gender, geographic area, and time of data collection.

RESULTS

Rh(D) positive cases were significantly less frequent in the patient group compared to controls (p=0.01). Pre-existing diabetes was associated with meningioma in middle-aged (40-69 years) patients (odds ratio, OR 13.94-4.30, p=0.001-0.05). In female patients, arterial hypertension was significantly associated with occurrence of meningioma in the age group 60-69 years (OR=2.23, p=0.041). Rheumatoid arthritis had a negative association with meningioma in both males and females in the age groups above 50 years (OR 0.19-0.27, p=0.02-0.034). Bronchial asthma, smoking, and obesity were not significantly associated with meningioma. A second primary tumour was present in 12 cases. The most frequent combination was meningioma and breast cancer (5/12).

CONCLUSIONS

This study shows statistically significant association of some co-morbidities with symptomatic meningioma in adults. Areas of interest have been identified where further research would be necessary.

Contacts with animals and humans as risk factors for adult brain tumours. An international case-control study

While numerous studies have addressed the possible role of farming and related exposures as risk factors for brain tumours in adults, few of them have examined the potential effect of exposure to farm animals or pets. In an international multicentre case-control study, we investigated whether residence on a farm, contact with animals, or working in occupations with a high degree of potential contact with animals or humans were associated with brain tumours. Using a common questionnaire, 1177 cases of glioma, 330 with meningioma and 2478 controls from eight centres were interviewed about the exposures and, in particular, about their contacts with nine species of animals: dairy cattle, beef cattle, pigs, horses, sheep, goats, poultry, dogs and cats. Living or working on a farm was not a risk factor, for either glioma or meningioma. Except in some centres, there was no relationship between having contacts with farm animals or pets and the risk of brain tumour, for either type of tumour or either sex. In relation to seven industrial groups involving frequent human and/or animal contacts, no association was apparent for either glioma or meningioma. In relation to 25 occupational groups with potential frequent contact with humans and/or animals, for glioma there was a reduced risk for biological technicians (Odds Ratio (OR)/=0, P=0.01), and general farm workers (OR=0.66, 95% Confidence Interval (CI): 0.5-0.9). For meningioma, there was an increased risk for cooks (OR=2.0; CI: 1.2-3.4). With some exceptions, these results indicate no association between either the type of brain tumour and contacts with animals, or with occupations that include a high level of contact with animals or a high level of contact with humans.

Associação entre fatores da dieta e tumores de cérebro em adultos: uma revisão da literatura

Desenvolveu-se uma revisão da literatura científica publicada entre 1986 e 1999, sobre a associação entre fatores da dieta e os tumores de cérebro em adultos, com o objetivo de descrever as associações observadas e discutir os aspectos metodológicos que possam influenciar os resultados observados. De um modo geral, os estudos revisados parecem apontar na direção de uma associação moderada entre os fatores da dieta e os tumores de cérebro; há evidências de que o consumo de compostos N-nitroso possa favorecer o desenvolvimento desses tumores, e de que o consumo de vegetais e frutas pode ter papel na sua inibição. A participação dos respondentes substitutos nos estudos analisados, pode ter introduzido viés de memória nas informações levantadas e contribuído para a inconsistência dos achados. As investigações epidemiológicas sobre a associação da dieta com estes tumores devem considerar a análise de outros fatores alimentares, além dos compostos N-nitroso. É necessário precisar os períodos de exposição que devem ser investigados e contar com criteriosa metodologia, de modo a prevenir a ocorrência de tendenciosidades relacionadas com a seleção dos controles e minimizar os efeitos do viés de memória.

Risk factors for meningioma in adults: a case-control study in northeast China

A hospital case-control study of meningioma was conducted in Heilongjiang Province in northeast China between September 1989 and December 1996. It included 183 cases of newly diagnosed primary meningioma and 366 individually matched hospital controls with non-neoplastic and non-neurological disease selected from six major hospitals. Cases and controls were matched by sex, age and area of residence and interviewed in the hospital wards to obtain information on medical history, occupation and lifestyle. No association with liquor or beer consumption was apparent. Cigarette smoking was positively associated with meningioma risk in women but not in men. In women, compared with non-smokers, the adjusted OR for pack-years of smoking above the median (124) was 6.2 (CI 2.04-18.87). Both of these observations contrast with the results of a study of glioma in the same population, using similar methods. The risk of meningioma was positively associated with reported occupational exposure to lead, tin, cadmium and ionising radiation in both genders.

Diet and brain cancer in adults: a case-control study in northeast China

A hospital-based case-control study was conducted in the Heilongjiang Province of northeast China between May 1993 and May 1995. A total of 129 histologically confirmed brain cancer cases (73 gliomas and 56 meningiomas) and 258 matched controls were interviewed in 6 major hospitals to examine the influence of dietary factors in developing brain cancer. Information was obtained about frequency of consumption of 57 food items. Odds ratios (ORs) were obtained from conditional logistic regression, including allowance for socio-demographic factors, alcohol, tobacco and total energy intake. Consumption of fresh vegetables (OR = 0.29 for the highest quartile compared with the lowest one), and specifically of Chinese cabbage and onion, fruit (OR = 0.15), fresh fish (OR = 0.38) and poultry (OR = 0.16) was inversely related to the risk of developing brain cancer. A protective effect was also seen for vitamin E intake, calcium and, although non-significantly, beta-carotene and vitamin C. Risk of brain cancer increased with consumption of salted vegetables (OR = 2.54) and salted fish.