Genetically Predicted Circulating C-Reactive Protein Concentration and Colorectal Cancer Survival: A Mendelian Randomization Consortium Study

Mendelian randomisation analysis for intestinal disease: achievement and future

Intestinal disease is a group of complex digestive system diseases imposing a significant burden globally. Identifying the risk factors and potential complications of intestinal disease is important for its prevention and treatment. However, traditional observational clinical studies are limited by confounding factors and reverse causation, making causal inference challenging. Mendelian randomisation (MR) method has been developed to effectively mitigate these constraints and assess the causal relationships. This review briefly introduces the MR method, summarises MR research on intestinal disease and delineates the prospective avenues for future research. Conventional risk factors, such as lifestyle behaviours (eg, physical activity, smoking and alcohol consumption), nutrients (eg, selenium), obesity markers (eg, body mass index and waist-to-hip ratio) and inflammatory biomarkers, have been validated in MR studies. Multiomics MR studies are becoming novel hotspots, which provide a theoretical foundation for the exploration of pathogenesis and the investigation of new drug targets. However, most of the recent studies are based on European individuals, and thus it is necessary to replicate the results in other ancestries. Moreover, triangulation integrating MR and other epidemiology methods is suggested as a validated paradigm for causal inference in future MR studies.

Postoperative serum interleukin-6 levels correlate with survival in stage I-III colorectal cancer

AIMS

The preoperative serum levels of inflammatory mediators, including C-reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6), have been demonstrated to be correlated with patient outcomes in colorectal cancer (CRC); however, the prognostic role of these levels has been less well-studied in postoperative settings.

MATERIALS AND METHODS

A total of 122 stage I-III CRC patients were retrospectively enrolled. Serum levels of CRP, PCT and IL-6 were measured after surgery, and their prognostic value was evaluated. Kaplan-Meier analysis was used to determine the differences in disease-free survival (DFS) and overall survival (OS) between patients with different levels of these mediators, and the Cox proportional hazards model was used to estimate the risk factors.

RESULTS

In contrast to CRP and PCT, only the level of IL-6 was significant in predicting DFS (P = 0.01) but not OS (P = 0.07). A total of 66.39% (81/122) of patients were assigned to the low IL-6 group and no significant differences were found in the collected clinicopathological parameters among the low or high IL-6 subgroups. The level of IL-6 was negatively correlated with postoperative (1 w) (R=-0.24, P = 0.02) absolute lymphocyte counts. Patients with low levels of IL-6 had better DFS (log rank = 6.10, P = 0.01) but not OS (log rank = 2.28, P = 0.13). Finally, the level of IL-6 was an independent risk factor for DFS (HR: 1.81, 95% CI: 1.03-3.15, P = 0.04).

CONCLUSIONS

Compared to CRP and PCT, the level of IL-6 was observed to be the only significant factor in predicting the prognosis of stage I-III CRC patients after surgery, and a low level of IL-6 was associated with good DFS.

A predictive role of C-reactive protein in colorectal cancer risk: an updated meta-analysis from 780,985 participants and 11,289 cancer cases

PURPOSE

This meta-analysis is aimed at understanding the potential role of circulating C-reactive protein (CRP) in the prediction of colorectal cancer (CRC) risk and the potential effect of relevant variables, with specific concern to determine the incorporation of CRP into a CRC risk prediction model.

METHODS

Relevant articles on the association between circulating CRP and CRC risk were searched from PubMed, Embase, Web of Science, and Cochrane Database of Systematic Reviews through August 2022. Random-effects models were used to estimate the pooled relative risk (RR) for the highest versus lowest CRP categories. Linear and non-linear trend analyses were conducted to explore the dose-response associations between CRP and CRC risk.

RESULTS

Twenty-three articles including 780,985 participants and 11,289 cancer cases met the selection criteria. The overall result demonstrated a remarkable association between elevated CRP levels and CRC risk (RR, 1.259; 95% CI, 1.060-1.457), but not in dose-response analysis (RR, 1.002 (95% CI, 0.964-1.041) per natural log unit change in CRP). Subgroup analyses indicated a significant difference when grouped by study location, the length of follow-up, and gender composition. No evidence of publication bias was observed.

CONCLUSION

The predictive role of CRP in CRC incidence is limited to colon cancer and a period of 10 years after the initial discovery of CRP elevation. The result did not support the etiological role of CRP in CRC and the inclusion of CRP into the CRC risk prediction model.

Strategies to investigate and mitigate collider bias in genetic and Mendelian randomisation studies of disease progression

Genetic studies of disease progression can be used to identify factors that may influence survival or prognosis, which may differ from factors that influence on disease susceptibility. Studies of disease progression feed directly into therapeutics for disease, whereas studies of incidence inform prevention strategies. However, studies of disease progression are known to be affected by collider (also known as "index event") bias since the disease progression phenotype can only be observed for individuals who have the disease. This applies equally to observational and genetic studies, including genome-wide association studies and Mendelian randomisation (MR) analyses. In this paper, our aim is to review several statistical methods that can be used to detect and adjust for index event bias in studies of disease progression, and how they apply to genetic and MR studies using both individual- and summary-level data. Methods to detect the presence of index event bias include the use of negative controls, a comparison of associations between risk factors for incidence in individuals with and without the disease, and an inspection of Miami plots. Methods to adjust for the bias include inverse probability weighting (with individual-level data), or Slope-Hunter and Dudbridge et al.'s index event bias adjustment (when only summary-level data are available). We also outline two approaches for sensitivity analysis. We then illustrate how three methods to minimise bias can be used in practice with two applied examples. Our first example investigates the effects of blood lipid traits on mortality from coronary heart disease, while our second example investigates genetic associations with breast cancer mortality.

Pre-diagnostic C-reactive protein concentrations, CRP genetic variation and mortality among individuals with colorectal cancer in Western European populations

BACKGROUND

The role of elevated pre-diagnostic C-reactive protein (CRP) concentrations on mortality in individuals with colorectal cancer (CRC) remains unclear.

METHODS

We investigated the association between pre-diagnostic high-sensitivity CRP concentrations and CRP genetic variation associated with circulating CRP and CRC-specific and all-cause mortality based on data from 1,235 individuals with CRC within the European Prospective Investigation into Cancer and Nutrition cohort using multivariable-adjusted Cox proportional hazards regression.

RESULTS

During a median follow-up of 9.3 years, 455 CRC-specific deaths were recorded, out of 590 deaths from all causes. Pre-diagnostic CRP concentrations were not associated with CRC-specific (hazard ratio, HR highest versus lowest quintile 0.92, 95% confidence interval, CI 0.66, 1.28) or all-cause mortality (HR 0.91, 95% CI 0.68, 1.21). Genetic predisposition to higher CRP (weighted score based on alleles of four CRP SNPs associated with higher circulating CRP) was not significantly associated with CRC-specific mortality (HR per CRP-score unit 0.95, 95% CI 0.86, 1.05) or all-cause mortality (HR 0.98, 95% CI 0.90, 1.07). Among four investigated CRP genetic variants, only SNP rs1205 was significantly associated with CRC-specific (comparing the CT and CC genotypes with TT genotype, HR 0.54, 95% CI 0.35, 0.83 and HR 0.58, 95% CI 0.38, 0.88, respectively) and all-cause mortality (HR 0.58, 95% CI 0.40, 0.85 and 0.64, 95% CI 0.44, 0.92, respectively).

CONCLUSIONS

The results of this prospective cohort study do not support a role of pre-diagnostic CRP concentrations on mortality in individuals with CRC. The observed associations with rs1205 deserve further scientific attention.

Association Between Genetic Predictors for C-Reactive Protein and Venous Thromboembolism With Severe Adverse Coronavirus Disease 2019 Outcomes

To assess if genetic predictors for C-reactive protein and risk of venous thromboembolism are associated with severe outcomes among individuals who tested positive for severe acute respiratory syndrome coronavirus 2.

DESIGN

Retrospective cohort study.

SETTING

U.K. Biobank.

PATIENTS OR SUBJECTS

U.K. Biobank participants with European ancestry who were recorded to have a positive polymerase chain reaction test result for severe acute respiratory syndrome coronavirus 2 between March 16, 2020, and August 14, 2020.

INTERVENTIONS

Not applicable.

MEASUREMENTS AND MAIN RESULTS

We constructed separate genetic risk scores for C-reactive protein and venous thromboembolism consisting of 56 and 37 genetic variants that have been significantly associated with venous thromboembolism and C-reactive protein, respectively. Among 1,126 individuals who were diagnosed with coronavirus disease 2019, 48% had a coronavirus disease 2019-related hospitalization, 16% received critical care support, 10% had critical respiratory support, and 21% died from coronavirus disease 2019. Genetic predisposition to high C-reactive protein concentrations was marginally associated with a lower risk of death from coronavirus disease 2019 (odds ratio, 0.85; 95% CI, 0.73-1.00; p = 0.05). No other associations were significant.

CONCLUSIONS

Our results do not support associations between polygenic risk for elevated blood C-reactive protein concentrations or venous thromboembolism and severe coronavirus disease 2019 health outcomes. Thus, considering genetic predisposition associated with C-reactive protein concentrations or venous thromboembolism risk is not meaningful for predicting severe coronavirus disease 2019 health outcomes.