| 1. |
- Battram, Thomas, et al.
(författare)
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Appraising the causal relevance of DNA methylation for risk of lung cancer
- 2019
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Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 48:5, s. 1493-1504
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Tidskriftsartikel (refereegranskat)abstract
- Background: DNA methylation changes in peripheral blood have recently been identified in relation to lung cancer risk. Some of these changes have been suggested to mediate part of the effect of smoking on lung cancer. However, limitations with conventional mediation analyses mean that the causal nature of these methylation changes has yet to be fully elucidated.Methods: We first performed a meta-analysis of four epigenome-wide association studies (EWAS) of lung cancer (918 cases, 918 controls). Next, we conducted a two-sample Mendelian randomization analysis, using genetic instruments for methylation at CpG sites identified in the EWAS meta-analysis, and 29 863 cases and 55 586 controls from the TRICL-ILCCO lung cancer consortium, to appraise the possible causal role of methylation at these sites on lung cancer.Results: Sixteen CpG sites were identified from the EWAS meta-analysis [false discovery rate (FDR) < 0.05], for 14 of which we could identify genetic instruments. Mendelian randomization provided little evidence that DNA methylation in peripheral blood at the 14 CpG sites plays a causal role in lung cancer development (FDR > 0.05), including for cg05575921-AHRR where methylation is strongly associated with both smoke exposure and lung cancer risk.Conclusions: The results contrast with previous observational and mediation analysis, which have made strong claims regarding the causal role of DNA methylation. Thus, previous suggestions of a mediating role of methylation at sites identified in peripheral blood, such as cg05575921-AHRR, could be unfounded. However, this study does not preclude the possibility that differential DNA methylation at other sites is causally involved in lung cancer development, especially within lung tissue.
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| 2. |
- Capella, Gabriel, et al.
(författare)
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DNA repair polymorphisms and the risk of stomach adenocarcinoma and severe chronic gastritis in the EPIC-EURGAST study
- 2008
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 37:6, s. 1316-1325
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Tidskriftsartikel (refereegranskat)abstract
- Background The contribution of genetic variation in DNA repair genes to gastric cancer (GC) risk remains essentially unknown. The aim of this study was to explore the relative contribution of DNA repair gene polymorphisms to GC risk and severe chronic atrophic gastritis (SCAG). Method A nested case control study within the EPIC cohort was performed including 246 gastric adenocarcinomas and 1175 matched controls. Controls with SCAG (n 91), as defined by low pepsinogen A (PGA) levels, and controls with no SCAG (n 1061) were also compared. Twelve polymorphisms at DNA repair genes (MSH2, MLH1, XRCC1, OGG1 and ERCC2) and TP53 gene were analysed. Antibodies against Helicobacter pylori were measured. Results No association was observed for any of these polymorphisms with stomach cancer risk. However, ERCC2 K751Q polymorphism was associated with an increased risk for non-cardial neoplasm [odds ratio (OR) 1.78; 95 confidence interval (CI) 1.023.12], being ERCC2 K751Q and D312N polymorphisms associated with the diffuse type. ERCC2 D312N (OR 2.0; 95 CI 1.093.65) and K751Q alleles (OR 1.82; 95 CI 1.013.30) and XRCC1 R399Q (OR 1.69; 95 CI 1.022.79) allele were associated with an increased risk for SCAG. Conclusion Our study supports a role of ERCC2 in non-cardial GC but not in cardial cancer. A concordant result was observed for subjects with low PGA levels. XRCC1 allele was associated also with SCAG. This is the first prospective study suggesting that individual variation in DNA repair may be relevant for gastric carcinogenesis, a finding that will require further confirmation validation in larger independent studies.
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| 3. |
- Gallo, Valentina, et al.
(författare)
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Exploring causality of the association between smoking and Parkinson's disease
- 2019
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 48:3, s. 912-925
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The aim of this paper is to investigate the causality of the inverse association between cigarette smoking and Parkinson's disease (PD). The main suggested alternatives include a delaying effect of smoking, reverse causality or an unmeasured confounding related to a low-risk-taking personality trait. METHODS: A total of 715 incident PD cases were ascertained in a cohort of 220 494 individuals from NeuroEPIC4PD, a prospective European population-based cohort study including 13 centres in eight countries. Smoking habits were recorded at recruitment. We analysed smoking status, duration, and intensity and exposure to passive smoking in relation to PD onset. RESULTS: Former smokers had a 20% decreased risk and current smokers a halved risk of developing PD compared with never smokers. Strong dose-response relationships with smoking intensity and duration were found. Hazard ratios (HRs) for smoking <20 years were 0.84 [95% confidence interval (CI) 0.67-1.07], 20-29 years 0.73 (95% CI 0.56-0.96) and >30 years 0.54 (95% CI 0.43-0.36) compared with never smokers. The proportional hazard assumption was verified, showing no change of risk over time, arguing against a delaying effect. Reverse causality was disproved by the consistency of dose-response relationships among former and current smokers. The inverse association between passive smoking and PD, HR 0.70 (95% CI 0.49-0.99) ruled out the effect of unmeasured confounding. CONCLUSIONS: These results are highly suggestive of a true causal link between smoking and PD, although it is not clear which is the chemical compound in cigarette smoking responsible for the biological effect.
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| 4. |
- Nagel, Gabriele, et al.
(författare)
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Socioeconomic positoon and the risk of gastric and overphageal cancer in the European Prospective into Cancer and Nutrition (EPIC-EURGAST)
- 2007
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 36:1, s. 66-76
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To evaluate the association of socioeconomic position with adenocarcinoma of the oesophagus and stomach. Methods The European Prospective Investigation into Cancer and Nutrition (EPIC) cohort comprises about 520000 participants mostly aged 35-70 years. Information on diet and lifestyle was collected at recruitment. After an average follow-up of 6.5 years, 268 cases with adenocarcinoma of the stomach and 56 of the oesophagus were confirmed. We examined the effect of socioeconomic position on cancer risk by means of educational data and a computed Relative Index of Inequality (RII). In a nested case-control study, adjustment for Helicobacter pylori (H. pylori) infection was performed. Results Higher education was significantly associated with a reduced risk of gastric cancer [vs lowest level of education, hazard ratio (HR): 0.64, 95% Confidence intervals (CI): 0.43-0.981. This effect was more pronounced for cancer of the cardia (HR: 0.42, 95% CI: 0.20-0.89) as compared to non-cardia gastric cancer (HR: 0.66, 95% CI: 0.36-1.22). Additionally, the inverse association of educational level and gastric cancer was stronger for cases with intestinal (extreme categories, HR: 0.13, 95% CI: 0.04-0.44) rather than diffuse histological subtype (extreme categories, HR: 0.71 95% CI: 0.37-1.40). In the nested case-control study, inverse but statistically non-significant associations were found after additional adjustment for H. pylori infection [highest vs lowest level of education: Odds ratio (OR) 0.53, 95% CI: 0.24-1.18]. Educational level was non-significantly, inversely associated with carcinoma of the oesophagus. Conclusion A higher socioeconomic position was associated with a reduced risk of gastric adenocarcinoma, which was strongest for cardia cancer or intestinal histological subtype, suggesting different risk profiles according to educational level. These effects appear to be explained only partially by established risk factors.
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| 5. |
- Porta, Miquel, et al.
(författare)
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Plasma concentrations of persistent organic pollutants and pancreatic cancer risk
- 2022
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Ingår i: International Journal of Epidemiology. - : Oxford University Press. - 0300-5771 .- 1464-3685. ; 51:2, s. 479-490
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Tidskriftsartikel (refereegranskat)abstract
- Background: Findings and limitations of previous studies on persistent organic pollutants (POPs) and pancreatic cancer risk support conducting further research in prospective cohorts.Methods: We conducted a prospective case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Participants were 513 pancreatic cancer cases and 1020 matched controls. Concentrations of 22 POPs were measured in plasma collected at baseline.Results: Some associations were observed at higher concentrations of p, p'-DDT, trans-nonachlor, β-hexachlorocyclohexane and the sum of six organochlorine pesticides and of 16 POPs. The odds ratio (OR) for the upper quartile of trans-nonachlor was 1.55 (95% confidence interval 1.06-2.26; P for trend = 0.025). Associations were stronger in the groups predefined as most valid (participants having fasted >6 h, with microscopic diagnostic confirmation, normal weight, and never smokers), and as most relevant (follow-up ≥10 years). Among participants having fasted >6 h, the ORs were relevant for 10 of 11 exposures. Higher ORs were also observed among cases with microscopic confirmation than in cases with a clinical diagnosis, and among normal-weight participants than in the rest of participants. Among participants with a follow-up ≥10 years, estimates were higher than in participants with a shorter follow-up (for trans-nonachlor: OR = 2.14, 1.01 to 4.53, P for trend = 0.035). Overall, trans-nonachlor, three PCBs and the two sums of POPs were the exposures most clearly associated with pancreatic cancer risk.Conclusions: Individually or in combination, most of the 22 POPs analysed did not or only moderately increased the risk of pancreatic cancer.
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| 6. |
- Sacerdote, Carlotta, et al.
(författare)
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Lower educational level is a predictor of incident type 2 diabetes in European countries : The EPIC-InterAct study
- 2012
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 41:4, s. 1162-1173
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Tidskriftsartikel (refereegranskat)abstract
- Background Type 2 diabetes mellitus ( T2DM) is one of the most common chronic diseases worldwide. In high- income countries, low socioeconomic status seems to be related to a high incidence of T2DM, but very little is known about the intermediate factors of this relationship.Method We performed a case-cohort study in eight Western European countries nested in the EPIC study (n = 340 234, 3.99 million person-years of follow-up). A random sub-cohort of 16 835 individuals and a total of 12 403 incident cases of T2DM were identified. Crude and multivariate-adjusted hazard ratios (HR) were estimated for each country and pooled across countries using meta-analytical methods. Age-, gender- and country-specific relative indices of inequality (RII) were used as the measure of educational level and RII tertiles were analysed.Results Compared with participants with a high educational level (RII tertile 1), participants with a low educational level (RII tertile 3) had a higher risk of T2DM [HR: 1.77, 95% confidence interval (CI): 1.69-1.85; P-trend < 0.01]. The HRs adjusted for physical activity, smoking status and propensity score according to macronutrient intake were very similar to the crude HR (adjusted HR: 1.67, 95% CI: 1.52-1.83 in men; HR: 1.88, 95% CI: 1.73-2.05 in women). The HRs were attenuated only when they were further adjusted for BMI (BMI-adjusted HR: 1.36, 95% CI: 1.23-1.51 in men; HR: 1.32, 95% CI: 1.20-1.45 in women).Conclusion This study demonstrates the inequalities in the risk of T2DM in Western European countries, with an inverse relationship between educational level and risk of T2DM that is only partially explained by variations in BMI.
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| 7. |
- Strömberg, Ulf, et al.
(författare)
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Ranking of genome-wide association scan signals by different measures.
- 2009
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 38, s. 1364-1373
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The P-value approach has been employed to prioritizing genome-wide association (GWA) scan signals, with a genome-wide significance defined by a prior P-value threshold, although this is not ideal. A rationale put forward is that the association signals rather should be expected to give less support for single nucleotide polymorphisms (SNPs) that are rare (with associated low-power tests) than for common SNPs with equivalent P-values, unless investigators believe, a priori, that rare causative variants contribute to the disease and have more pronounced effects. METHODS: Using data from a GWA scan for type 2 diabetes (1924 cases, 2938 controls, 393 453 SNPs), we compared P-values with four alternative signal measures: likelihood ratio (LR), Bayes factor (BF; with a specified prior distribution for true effects), 'frequentist factor' (FF; reflecting the ratio between estimated-post-data- 'power' and P-value) and probability of pronounced effect size (PrPES). RESULTS: The 19 common SNPs [minor allele frequency (MAF) among the controls >29%] yielding strong P-value signals (P < 5 x 10(-7)) were also top ranked by the other approaches. There was a strong similarity between the P-values, LR and BF signals, in terms of ranking SNPs. In contrast, FF and PrPES signals down-weighted rare SNPs (control MAF <10%) with low P-values. CONCLUSIONS: For prioritization of signals that do not achieve compelling levels of evidence for association, the main driving force behind observed differences between the various association signals appears to be SNP MAF. The statistical power afforded by follow-up samples for establishing replication should be taken into account when tailoring the signal selection strategy.
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| 8. |
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