Background: Data on the effects of glucagon-like peptide-1 receptor agonists (GLP-1RAs) on pancreatic cancer incidence are limited and inconsistent. Here we evaluate the association of GLP-1RAs, alone and in combinations, with incident pancreatic cancer risk in a real-world population, stratified by obesity and smoking status. Methods: This retrospective cohort included patients with type 2 diabetes mellitus who were prescribed GLP-1RAs or other nonglucagon-like peptide-1 receptor agonist antidiabetes medications between January 2013 and March 2019 and had no prior diagnosis of pancreatic cancer. The incident (first-time) diagnosis of pancreatic cancer during a 5-year follow-up was compared between propensity-score matched cohorts of patients prescribed GLP-1RAs vs other nonglucagon-like peptide-1 receptor agonist antidiabetes medications. Subgroup analyses were performed in patients stratified by the status of obesity and tobacco use disorder. We also compared GLP-1RA combination therapies with monotherapies. Time-to-first-event analysis was performed using Cox proportional hazards and Kaplan–Meier survival analysis, with the hazard ratio and 95% confidence interval calculated. Results: The study population comprised 1 636 056 eligible patients including 167 091 prescribed GLP-1RAs and 1 468 965 prescribed other antidiabetes medications. GLP-1RAs were associated with a statistically significant decreased risk for pancreatic cancer incidence compared with each of 6 nonglucagon-like peptide-1 receptor agonist antidiabetes medications with hazard ratios ranging from 0.42 to 0.82. The reduction was greater in patients with obesity and tobacco use disorder than in those without. GLP-1RA combination therapies were associated with lower pancreatic cancer risk compared with monotherapies. Conclusions: GLP-1RAs were associated with reduced pancreatic cancer incidence in patients with type 2 diabetes mellitus. Further studies and trials are needed to explore mechanisms and confirm causal effects.

Background: Epigenetic clock, or DNA methylation age, has been shown to highly correlate with chronologic age. Epigenetic age acceleration, the difference between DNA methylation age and individual9s chronologic age, was observed in colorectal cancer. However, the association of epigenetic age acceleration with colorectal cancer tumor molecular characteristics, clinical characteristics, and patient outcomes has not been systematically investigated. Methods: DNA methylation ages of 345 patients with colorectal cancer from The Cancer Genome Atlas (TCGA) were computed using the Horvath age prediction model. Multivariate linear regression was used to assess the association of epigenetic age acceleration with molecular and clinical features of colorectal cancer, including consensus molecular subtypes (CMS1–CMS4) and tumor stage Cox proportional hazards regression was used to assess the association of epigenetic age acceleration with survival. Results: Epigenetic age acceleration is significantly associated with CMS. Compared with CMS2, epigenetic age acceleration for CMS1, CMS3, and CMS4 was 23.90 years [P = 5.55E-11; 95% confidence interval (CI): 17.10–30.69], 9.16 years (P = 5.84E-03; 95% CI: 2.68–15.65), and 6.05 years (P = 2.69E-02; 95% CI: 0.70–11.41), respectively. Furthermore, epigenetic age acceleration is statistically significantly and positively associated with total mortality (HR = 1.97; 95% CI: 1.14–3.39; P = 0.014). Conclusions: Epigenetic age acceleration is associated with colorectal cancer tumor molecular characteristics, and a significant predictor of overall survival of colorectal cancer, along with age and tumor stage. Impact: Combining information of colonic tissue epigenetic age acceleration and tumor molecular characteristics may improve prognosis prediction in colorectal cancer.

There are well-documented racial differences in age-of-onset and laterality of colorectal cancer. Epigenetic age acceleration is postulated to be an underlying factor. However, comparative studies of side-specific colonic tissue epigenetic aging are lacking. Here, we performed DNA methylation analysis of matched right and left biopsies of normal colon from 128 individuals. Among African Americans (n = 88), the right colon showed accelerated epigenetic aging as compared with individual-matched left colon (1.51 years; 95% confidence interval [CI] = 0.62 to 2.40 years; 2-sided P = .001). In contrast, among European Americans (n = 40), the right colon shows remarkable age deceleration (1.93 years; 95% CI = 0.65 to 3.21 years; 2-sided P = .004). Further, epigenome-wide analysis of DNA methylation identifies a unique pattern of hypermethylation in African American right colon. Our study is the first to report such race and side-specific differences in epigenetic aging of normal colon, providing novel insight into the observed younger age-of-onset and relative preponderance of right-side colon neoplasia in African Americans.

Colorectal cancer risk can be impacted by genetic, environmental, and lifestyle factors, including diet and obesity. Gene-environment interactions (G × E) can provide biological insights into the effects of obesity on colorectal cancer risk. Here, we assessed potential genome-wide G × E interactions between body mass index (BMI) and common SNPs for colorectal cancer risk using data from 36,415 colorectal cancer cases and 48,451 controls from three international colorectal cancer consortia (CCFR, CORECT, and GECCO). The G × E tests included the conventional logistic regression using multiplicative terms (one degree of freedom, 1DF test), the two-step EDGE method, and the joint 3DF test, each of which is powerful for detecting G × E interactions under specific conditions. BMI was associated with higher colorectal cancer risk. The two-step approach revealed a statistically significant G×BMI interaction located within the Formin 1/Gremlin 1 (FMN1/GREM1) gene region (rs58349661). This SNP was also identified by the 3DF test, with a suggestive statistical significance in the 1DF test. Among participants with the CC genotype of rs58349661, overweight and obesity categories were associated with higher colorectal cancer risk, whereas null associations were observed across BMI categories in those with the TT genotype. Using data from three large international consortia, this study discovered a locus in the FMN1/GREM1 gene region that interacts with BMI on the association with colorectal cancer risk. Further studies should examine the potential mechanisms through which this locus modifies the etiologic link between obesity and colorectal cancer. Significance: This gene-environment interaction analysis revealed a genetic locus in FMN1/GREM1 that interacts with body mass index in colorectal cancer risk, suggesting potential implications for precision prevention strategies.

A polygenic risk score (PRS) is used to quantify the combined disease risk of many genetic variants. For complex human traits there is interest in determining whether the PRS modifies, i.e. interacts with, important environmental (E) risk factors. Detection of a PRS by environment (PRS x E) interaction may provide clues to underlying biology and can be useful in developing targeted prevention strategies for modifiable risk factors. The standard PRS may include a subset of variants that interact with E but a much larger subset of variants that affect disease without regard to E. This latter subset will dilute the underlying signal in former subset, leading to reduced power to detect PRS x E interaction. We explore the use of pathway-defined PRS (pPRS) scores, using state of the art tools to annotate subsets of variants to genomic pathways. We demonstrate via simulation that testing targeted pPRS x E interaction can yield substantially greater power than testing overall PRS x E interaction. We also analyze a large study (N = 78,253) of colorectal cancer (CRC) where E = non-steroidal anti-inflammatory drugs (NSAIDs), a well-established protective exposure. While no evidence of overall PRS x NSAIDs interaction (p = 0.41) is observed, a significant pPRS x NSAIDs interaction (p = 0.0003) is identified based on SNPs within the TGF-β/ gonadotropin releasing hormone receptor (GRHR) pathway. NSAIDS is protective (OR=0.84) for those at the 5^th percentile of the TGF-β/GRHR pPRS (low genetic risk, OR), but significantly more protective (OR=0.70) for those at the 95^th percentile (high genetic risk). From a biological perspective, this suggests that NSAIDs may act to reduce CRC risk specifically through genes in these pathways. From a population health perspective, our result suggests that focusing on genes within these pathways may be effective at identifying those for whom NSAIDs-based CRC-prevention efforts may be most effective.

Background: High red meat and/or processed meat consumption are established colorectal cancer risk factors. We conducted a genome-wide gene–environment (GxE) interaction analysis to identify genetic variants that may modify these associations. Methods: A pooled sample of 29,842 colorectal cancer cases and 39,635 controls of European ancestry from 27 studies were included. Quantiles for red meat and processed meat intake were constructed from harmonized questionnaire data. Genotyping arrays were imputed to the Haplotype Reference Consortium. Two-step EDGE and joint tests of GxE interaction were utilized in our genome-wide scan. Results: Meta-analyses confirmed positive associations between increased consumption of red meat and processed meat with colorectal cancer risk [per quartile red meat OR = 1.30; 95% confidence interval (CI) = 1.21–1.41; processed meat OR = 1.40; 95% CI = 1.20–1.63]. Two significant genome-wide GxE interactions for red meat consumption were found. Joint GxE tests revealed the rs4871179 SNP in chromosome 8 (downstream of HAS2); greater than median of consumption ORs = 1.38 (95% CI = 1.29–1.46), 1.20 (95% CI = 1.12–1.27), and 1.07 (95% CI = 0.95–1.19) for CC, CG, and GG, respectively. The two-step EDGE method identified the rs35352860 SNP in chromosome 18 (SMAD7 intron); greater than median of consumption ORs = 1.18 (95% CI = 1.11–1.24), 1.35 (95% CI = 1.26–1.44), and 1.46 (95% CI = 1.26–1.69) for CC, CT, and TT, respectively. Conclusions: We propose two novel biomarkers that support the role of meat consumption with an increased risk of colorectal cancer. Impact: The reported GxE interactions may explain the increased risk of colorectal cancer in certain population subgroups.