| 1. |
- Disney-Hogg, Linden, et al.
(author)
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Influence of obesity-related risk factors in the aetiology of glioma
- 2018
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In: British Journal of Cancer. - : Nature Publishing Group. - 0007-0920 .- 1532-1827. ; 118:7, s. 1020-1027
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Journal article (peer-reviewed)abstract
- BACKGROUND: Obesity and related factors have been implicated as possible aetiological factors for the development of glioma in epidemiological observation studies. We used genetic markers in a Mendelian randomisation framework to examine whether obesity-related traits influence glioma risk. This methodology reduces bias from confounding and is not affected by reverse causation. METHODS: Genetic instruments were identified for 10 key obesity-related risk factors, and their association with glioma risk was evaluated using data from a genome-wide association study of 12,488 glioma patients and 18,169 controls. The estimated odds ratio of glioma associated with each of the genetically defined obesity-related traits was used to infer evidence for a causal relationship. RESULTS: No convincing association with glioma risk was seen for genetic instruments for body mass index, waist-to-hip ratio, lipids, type-2 diabetes, hyperglycaemia or insulin resistance. Similarly, we found no evidence to support a relationship between obesity-related traits with subtypes of glioma-glioblastoma (GBM) or non-GBM tumours. CONCLUSIONS: This study provides no evidence to implicate obesity-related factors as causes of glioma.
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| 2. |
- Takahashi, Hannah, et al.
(author)
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Mendelian randomisation study of the relationship between vitamin D and risk of glioma
- 2018
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In: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
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Journal article (peer-reviewed)abstract
- To examine for a causal relationship between vitamin D and glioma risk we performed an analysis of genetic variants associated with serum 25-hydroxyvitamin D (25(OH) D) levels using Mendelian randomisation (MR), an approach unaffected by biases from confounding. Two-sample MR was undertaken using genome-wide association study data. Single nucleotide polymorphisms (SNPs) associated with 25(OH) D levels were used as instrumental variables (IVs). We calculated MR estimates for the odds ratio (OR) for 25(OH) D levels with glioma using SNP-glioma estimates from 12,488 cases and 18,169 controls, using inverse-variance weighted (IVW) and maximum likelihood estimation (MLE) methods. A non-significant association between 25(OH) D levels and glioma risk was shown using both the IVW (OR = 1.21, 95% confidence interval [CI] = 0.90-1.62, P = 0.201) and MLE (OR = 1.20, 95% CI = 0.98-1.48, P = 0.083) methods. In an exploratory analysis of tumour subtype, an inverse relationship between 25(OH)D levels and glioblastoma (GBM) risk was identified using the MLE method (OR = 0.62, 95% CI = 0.43-0.89, P = 0.010), but not the IVW method (OR = 0.62, 95% CI = 0.37-1.04, P = 0.070). No statistically significant association was shown between 25(OH) D levels and non-GBM glioma. Our results do not provide evidence for a causal relationship between 25(OH) D levels and all forms of glioma risk. More evidence is required to explore the relationship between 25(OH) D levels and risk of GBM.
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