Dataset Information

Mendelian randomization analysis of C-reactive protein on colorectal cancer risk.

ABSTRACT: BACKGROUND:Chronic inflammation is a risk factor for colorectal cancer (CRC). Circulating C-reactive protein (CRP) is also moderately associated with CRC risk. However, observational studies are susceptible to unmeasured confounding or reverse causality. Using genetic risk variants as instrumental variables, we investigated the causal relationship between genetically elevated CRP concentration and CRC risk, using a Mendelian randomization approach. METHODS:Individual-level data from 30 480 CRC cases and 22 844 controls from 33 participating studies in three international consortia were used: the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colorectal Transdisciplinary Study (CORECT) and the Colon Cancer Family Registry (CCFR). As instrumental variables, we included 19 single nucleotide polymorphisms (SNPs) previously associated with CRP concentration. The SNP-CRC associations were estimated using a logistic regression model adjusted for age, sex, principal components and genotyping phases. An inverse-variance weighted method was applied to estimate the causal effect of CRP on CRC risk. RESULTS:Among the 19 CRP-associated SNPs, rs1260326 and rs6734238 were significantly associated with CRC risk (P?=?7.5?×?10-4, and P?=?0.003, respectively). A genetically predicted one-unit increase in the log-transformed CRP concentrations (mg/l) was not associated with increased risk of CRC [odds ratio (OR)?=?1.04; 95% confidence interval (CI): 0.97, 1.12; P?=?0.256). No evidence of association was observed in subgroup analyses stratified by other risk factors. CONCLUSIONS:In spite of adequate statistical power to detect moderate association, we found genetically elevated CRP concentration was not associated with increased risk of CRC among individuals of European ancestry. Our findings suggested that circulating CRP is unlikely to be a causal factor in CRC development.

SUBMITTER: Wang X

PROVIDER: S-EPMC6659358 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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Mendelian randomization analysis of C-reactive protein on colorectal cancer risk.

Wang Xiaoliang X Dai James Y JY Albanes Demetrius D Arndt Volker V Berndt Sonja I SI Bézieau Stéphane S Brenner Hermann H Buchanan Daniel D DD Butterbach Katja K Caan Bette B Casey Graham G Campbell Peter T PT Chan Andrew T AT Chen Zhengyi Z Chang-Claude Jenny J Cotterchio Michelle M Easton Douglas F DF Giles Graham G GG Giovannucci Edward E Grady William M WM Hoffmeister Michael M Hopper John L JL Hsu Li L Jenkins Mark A MA Joshi Amit D AD Lampe Johanna W JW Larsson Susanna C SC Lejbkowicz Flavio F Li Li L Lindblom Annika A Le Marchand Loic L Martin Vicente V Milne Roger L RL Moreno Victor V Newcomb Polly A PA Offitt Kenneth K Ogino Shuji S Pharoah Paul D P PDP Pinchev Mila M Potter John D JD Rennert Hedy S HS Rennert Gad G Saliba Walid W Schafmayer Clemens C Schoen Robert E RE Schrotz-King Petra P Slattery Martha L ML Song Mingyang M Stegmaier Christa C Weinstein Stephanie J SJ Wolk Alicja A Woods Michael O MO Wu Anna H AH Gruber Stephen B SB Peters Ulrike U White Emily E

International journal of epidemiology 20190601 3

<h4>Background</h4>Chronic inflammation is a risk factor for colorectal cancer (CRC). Circulating C-reactive protein (CRP) is also moderately associated with CRC risk. However, observational studies are susceptible to unmeasured confounding or reverse causality. Using genetic risk variants as instrumental variables, we investigated the causal relationship between genetically elevated CRP concentration and CRC risk, using a Mendelian randomization approach.<h4>Methods</h4>Individual-level data fr ...[more]

PMID: 30476131

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Project description:BackgroundHigher adiposity increases the risk of colorectal cancer (CRC), but whether this relationship varies by anatomical sub-site or by sex is unclear. Further, the metabolic alterations mediating the effects of adiposity on CRC are not fully understood.MethodsWe examined sex- and site-specific associations of adiposity with CRC risk and whether adiposity-associated metabolites explain the associations of adiposity with CRC. Genetic variants from genome-wide association studies of body mass index (BMI) and waist-to-hip ratio (WHR, unadjusted for BMI; N = 806,810), and 123 metabolites from targeted nuclear magnetic resonance metabolomics (N = 24,925), were used as instruments. Sex-combined and sex-specific Mendelian randomization (MR) was conducted for BMI and WHR with CRC risk (58,221 cases and 67,694 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium, Colorectal Cancer Transdisciplinary Study, and Colon Cancer Family Registry). Sex-combined MR was conducted for BMI and WHR with metabolites, for metabolites with CRC, and for BMI and WHR with CRC adjusted for metabolite classes in multivariable models.ResultsIn sex-specific MR analyses, higher BMI (per 4.2 kg/m2) was associated with 1.23 (95% confidence interval (CI) = 1.08, 1.38) times higher CRC odds among men (inverse-variance-weighted (IVW) model); among women, higher BMI (per 5.2 kg/m2) was associated with 1.09 (95% CI = 0.97, 1.22) times higher CRC odds. WHR (per 0.07 higher) was more strongly associated with CRC risk among women (IVW OR = 1.25, 95% CI = 1.08, 1.43) than men (IVW OR = 1.05, 95% CI = 0.81, 1.36). BMI or WHR was associated with 104/123 metabolites at false discovery rate-corrected P ≤ 0.05; several metabolites were associated with CRC, but not in directions that were consistent with the mediation of positive adiposity-CRC relations. In multivariable MR analyses, associations of BMI and WHR with CRC were not attenuated following adjustment for representative metabolite classes, e.g., the univariable IVW OR for BMI with CRC was 1.12 (95% CI = 1.00, 1.26), and this became 1.11 (95% CI = 0.99, 1.26) when adjusting for cholesterol in low-density lipoprotein particles.ConclusionsOur results suggest that higher BMI more greatly raises CRC risk among men, whereas higher WHR more greatly raises CRC risk among women. Adiposity was associated with numerous metabolic alterations, but none of these explained associations between adiposity and CRC. More detailed metabolomic measures are likely needed to clarify the mechanistic pathways.

Project description:Background: Previous observational studies have provided inconsistent evidence for the association between alcohol consumption and the risk of colorectal cancer (CRC). To assess this potential causal effect, we performed bidirectional Mendelian randomization (MR) analysis. Methods: We selected six single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) associated with alcohol consumption (ever versus never drinker) and two SNPs representing the number of drinks per week from a genome-wide association study (GWAS) of the Japanese population. Summary data for CRC were obtained from a GWAS meta-analysis in the Japanese population of 6,692 CRC cases and 27,178 controls. MR analysis was performed by the inverse-variance weighted (IVW) method primarily, supplemented with several sensitivity methods including the weighted median method, maximum likelihood method, MR pleiotropy residual sum and outlier (MR-PRESSO) test, MR-Egger regression, Causal Analysis Using Summary Effect estimates (CAUSE) method, as well as constrained maximum likelihood and model averaging and Bayesian information criterion (cML-MA-BIC) method. Multivariable Mendelian randomization (MMR) analyses were used to adjust for potential confounders. Reverse MR analyses were also performed to assess the potential causal effect of CRC on alcohol consumption. Results: Genetically predicted alcohol consumption (ever versus never drinker) was positively associated with the risk of CRC (odds ratio (OR) = 1.08, 95% confidence interval (CI): 1.05-1.12, p = 1.51 × 10-5 by IVW). The number of alcoholic drinks per week was also associated with an increased risk of CRC (OR = 1.39, 95%CI: 1.27-1.52, p = 5.29 × 10-13 by IVW). Sensitivity analysis yielded similar results. Reverse MR analyses found no evidence that CRC contributes to either ever drinkers (OR = 1.00, 95%CI: 0.99-1.00, p = 0.339 by IVW) or added number of drinks per week (OR = 1.01, 95%CI: 0.98-1.05, p = 0.545 by IVW). Conclusion: Our study suggested a potential causal association between alcohol consumption and the risk of CRC among Asians. Reducing drinking may be beneficial to the prevention and management of CRC.

Project description:Background: Results from epidemiologic studies examining polyunsaturated fatty acids (PUFA) and colorectal cancer risk are inconsistent. Mendelian randomization may strengthen causal inference from observational studies. Given their shared metabolic pathway, examining the combined effects of aspirin/NSAID use with PUFAs could help elucidate an association between PUFAs and colorectal cancer risk.Methods: Information was leveraged from genome-wide association studies (GWAS) regarding PUFA-associated SNPs to create weighted genetic scores (wGS) representing genetically predicted circulating blood PUFAs for 11,016 non-Hispanic white colorectal cancer cases and 13,732 controls in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Associations per SD increase in the wGS were estimated using unconditional logistic regression. Interactions between PUFA wGSs and aspirin/NSAID use on colorectal cancer risk were also examined.Results: Modest colorectal cancer risk reductions were observed per SD increase in circulating linoleic acid [ORLA = 0.96; 95% confidence interval (CI) = 0.93-0.98; P = 5.2 × 10-4] and ?-linolenic acid (ORALA = 0.95; 95% CI = 0.92-0.97; P = 5.4 × 10-5), whereas modest increased risks were observed for arachidonic (ORAA = 1.06; 95% CI = 1.03-1.08; P = 3.3 × 10-5), eicosapentaenoic (OREPA = 1.04; 95% CI = 1.01-1.07; P = 2.5 × 10-3), and docosapentaenoic acids (ORDPA = 1.03; 95% CI = 1.01-1.06; P = 1.2 × 10-2). Each of these effects was stronger among aspirin/NSAID nonusers in the stratified analyses.Conclusions: Our study suggests that higher circulating shorter-chain PUFAs (i.e., LA and ALA) were associated with reduced colorectal cancer risk, whereas longer-chain PUFAs (i.e., AA, EPA, and DPA) were associated with an increased colorectal cancer risk.Impact: The interaction of PUFAs with aspirin/NSAID use indicates a shared colorectal cancer inflammatory pathway. Future research should continue to improve PUFA genetic instruments to elucidate the independent effects of PUFAs on colorectal cancer.

Dataset Information

Mendelian randomization analysis of C-reactive protein on colorectal cancer risk.

Publications

Mendelian randomization analysis of C-reactive protein on colorectal cancer risk.

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