Meta-analysisAssociation between processed meat and red meat consumption and risk for glioma: A meta-analysis from 14 articles
Introduction
Glioma is the most common primary brain tumor that occurs most frequently in adults, accounting for ∼70% of adult brain malignancies [1], [2]. Glioma has an incidence of 5 to 10 cases per 100 000 [1]. It has been suggested that genetic predisposition and ionizing radiation are risk factors for brain tumors [3], [4]. Additionally, other potential risk factors include exposure to environmental chemical carcinogens, such as chemical agents and, among dietary factors, exposure to N-nitroso compounds [1], [3]. N-nitroso compounds are broadly acting and potent carcinogens in animal models [5]. Food items that usually include N-nitroso compounds are namely, processed meats, such as ham, hot dogs, salami, bacon, and lunchmeat.
Meat is a major source of protein and fat for humans. An association has been suggested between consumption of meat, in particular processed meat, and an increased risk for some diseases, including cancers [6], [7], stroke [8], type 2 diabetes [9], and cardiovascular disease [10]. Processed meats are usually preserved with nitrite and also may contain N-nitroso compounds. N-nitroso compounds can further be formed endogenously in the stomach from nitrites and ingested amides in foods of animal origin [11]. The hypothesis that N-nitroso compounds may be involved in the etiology of brain tumors comes both from observations in animal studies that these compounds may be able to pass through the blood–brain barrier, and that such compounds may be highly carcinogenic in animals [12]. In this meta-analysis, we sought to provide evidence consistent with this hypothesis that high levels of processed meat consumption could increase the risk for glioma.
Section snippets
Search strategy
A comprehensive search was conducted for available articles published in English using the databases of PubMed and Web of Knowledge up to February 2014. The following search terms were used: glioma or cancer or brain cancer AND red meat (unprocessed) or cured meat or processed meat or diet or lifestyle or food. We also searched for relevant papers in the reference list of reviews, commentaries, or original papers through the string N-nitroso brain cancer hypothesis [13], [14], [15] by hand
Search results and study characteristics
We identified 14 articles [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34] that were eligible for inclusion in the meta-analysis. Among these articles, 10 were carried out in the United States, 2 in Europe, 1 in Australia, and 1 in Israel. Sample sizes ranged from 48 to 3671 for case–control studies and 34 000 to 545 770 for cohort studies. Combined, these studies involved 3896 glioma cases and 877 640 participants. Characteristics of these studies are
Discussion
Findings from this meta-analysis suggested that the intake of processed meat might increase the risk for glioma. Most of the data on the issue come from the United States; thus it is obvious that the RR estimate for the United States reflects that for overall studies combined. We cannot combine the results for Europe, Australia, and Israel because of limited data. Furthermore, only three studies were conducted for red meat, and no association was found between red meat consumption and glioma
Conclusion
Results from this meta-analysis, including data mostly from the United States, suggest that processed meat consumption might increase the risk for glioma. Our findings are consistent with the hypothesis. No association was found between red meat consumption and glioma risk.
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2020, Clinical NutritionCitation Excerpt :Limited data exists regarding risk factors for gliomas; however, some risk factors have been identified including type of job, external carcinogens, allergies or atopic disease [5,6]. Several foods and nutrients, like fruits and vegetables [8], antioxidants and phytoestrogens [9,10], n-3 polyunsaturated fatty acids [11], nitrate or nitrite [12,13] and consumption of processed meats [14] have been identified as risk or protective factors. Further, inflammation contributes to the development of some cancers, including gliomas [15,16].
Patterns of nutrients intakes in relation to glioma: A case-control study
2019, Clinical NutritionCitation Excerpt :These nutrients are found in meats and processed meats. Greater intakes of meats and processed meats has been directly associated with the risk of glioma [32]. However, controlling for potential confounders made this relationship non-significant.
Epidemiology and Overview of Gliomas
2018, Seminars in Oncology NursingCitation Excerpt :The authors concluded that dietary nitrate and nitrite are not associated with the risk of adult glioma. Similarly, Wei and colleagues62 investigated 14 studies (3,641 glioma cases) on processed meat consumption and three studies (1,156 cases) about red meat consumption, and while finding no statistically significant associations between red meat consumption and glioma risk, they did suggest a possible association between processed meat consumption and glioma in studies conducted in the United States. However, Wei et al,62 did point out potential limitations of the US study, including (1) the association was only significant in the case-control studies, not in cohort studies, (2) that other genetic and environmental variables may also be contributors, and (3) the inherent limitations of case-control studies such as recall or selection bias.
The etiopathogenesis of diffuse low-grade gliomas
2017, Critical Reviews in Oncology/HematologyCitation Excerpt :However, this hypothesis is to be considered with caution. Indeed, processed meat has been inconsistently associated with glioma risk in epidemiological studies, with a modest increase of the glioma risk associated with consumption of processed meat in case-control studies but not in cohort studies in two recent meta-analyses (Saneei et al., 2015; Wei et al., 2015). Other diet factors have been studied, but none has been associated with DLGG or glioma risk yet.
A case-control study on dietary quality indices and glioma
2019, British Journal of NutritionAdherence to the Dietary Approaches to Stop Hypertension-style diet in relation to glioma: A case-control study
2016, British Journal of Nutrition
YDW conceived of the study and drafted the manuscript. YDW, DZZ, and DC carried out the literature search and data extraction. PX analyzed the data.