Combining Asian and European genome-wide association studies of colorectal cancer improves risk prediction across racial and ethnic populations

Polygenic risk scores (PRS) have great potential to guide precision colorectal cancer (CRC) prevention by identifying those at higher risk to undertake targeted screening. However, current PRS using European ancestry data have sub-optimal performance in non-European ancestry populations, limiting their utility among these populations. Towards addressing this deficiency, we expand PRS development for CRC by incorporating Asian ancestry data (21,731 cases; 47,444 controls) into European ancestry training datasets (78,473 cases; 107,143 controls). The AUC estimates (95% CI) of PRS are 0.63(0.62-0.64), 0.59(0.57-0.61), 0.62(0.60-0.63), and 0.65(0.63-0.66) in independent datasets including 1681-3651 cases and 8696-115,105 controls of Asian, Black/African American, Latinx/Hispanic, and non-Hispanic White, respectively. They are significantly better than the European-centric PRS in all four major US racial and ethnic groups (p-values < 0.05). Further inclusion of non-European ancestry populations, especially Black/African American and Latinx/Hispanic, is needed to improve the risk prediction and enhance equity in applying PRS in clinical practice

Genome-wide association studies and Mendelian randomization analyses provide insights into the causes of early-onset colorectal cancer

Background: The incidence of early-onset colorectal cancer (EOCRC; diagnosed &lt;50 years of age) is rising globally; however, the causes underlying this trend are largely unknown. CRC has strong genetic and environmental determinants, yet common genetic variants and causal modifiable risk factors underlying EOCRC are unknown. We conducted the first EOCRC-specific genome-wide association study (GWAS) and Mendelian randomization (MR) analyses to explore germline genetic and causal modifiable risk factors associated with EOCRC. Patients and methods: We conducted a GWAS meta-analysis of 6176 EOCRC cases and 65 829 controls from the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), the Colorectal Transdisciplinary Study (CORECT), the Colon Cancer Family Registry (CCFR), and the UK Biobank. We then used the EOCRC GWAS to investigate 28 modifiable risk factors using two-sample MR. Results: We found two novel risk loci for EOCRC at 1p34.1 and 4p15.33, which were not previously associated with CRC risk. We identified a deleterious coding variant (rs36053993, G396D) at polyposis-associated DNA repair gene MUTYH (odds ratio 1.80, 95% confidence interval 1.47-2.22) but show that most of the common genetic susceptibility was from noncoding signals enriched in epigenetic markers present in gastrointestinal tract cells. We identified new EOCRC-susceptibility genes, and in addition to pathways such as transforming growth factor (TGF) β, suppressor of Mothers Against Decapentaplegic (SMAD), bone morphogenetic protein (BMP) and phosphatidylinositol kinase (PI3K) signaling, our study highlights a role for insulin signaling and immune/infection-related pathways in EOCRC. In our MR analyses, we found novel evidence of probable causal associations for higher levels of body size and metabolic factors—such as body fat percentage, waist circumference, waist-to-hip ratio, basal metabolic rate, and fasting insulin—higher alcohol drinking, and lower education attainment with increased EOCRC risk. Conclusions: Our novel findings indicate inherited susceptibility to EOCRC and suggest modifiable lifestyle and metabolic targets that could also be used to risk-stratify individuals for personalized screening strategies or other interventions

Genome-wide association study and Mendelian randomization analyses provide insights into the causes of early-onset colorectal cancer

Background:The incidence of early-onset colorectal cancer (EOCRC; diagnosed &lt;50 years of age) is rising globally; however, the causes underlying this trend are largely unknown. Colorectal cancer (CRC) has strong genetic and environmental determinants, yet common genetic variants and causal modifiable risk factors underlying EOCRC are unknown. We conducted the first EOCRC-specific genome-wide association study (GWAS) and Mendelian randomization analyses to explore germline genetic and causal modifiable risk factors associated with EOCRC.Patients and methods:We conducted a genome-wide association study meta-analysis of 6,176 EOCRC cases and 65,829 controls from Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO), Colorectal Transdisciplinary study (CORECT), Colon Cancer Family Registry (CCFR), and UK Biobank. We then used the EOCRC GWAS to investigate 28 modifiable risk factors using two-sample Mendelian randomization (MR). Results:We found two novel risk loci for EOCRC at 1p34.1 and 4p15.33, not previously associated with CRC risk. We identified a deleterious coding variant (rs36053993, G396D) at polyposis-associated DNA repair gene MUTYH (OR=1.80 [95%CI=1.47-2.22]) but show that most of the common genetic susceptibility was from non-coding signals enriched in epigenetic markers present in gastrointestinal tract cells. We identified new EOCRC susceptibility genes, and in addition to pathways such as TGFβ, SMAD, BMP, and PI3K signaling, our study highlights a role for insulin signaling and immune/infection-related pathways in EOCRC. In our MR analyses, we found novel evidence of probable causal associations for higher levels of body size and metabolic factors - such as body fat percentage, waist circumference, waist to hip ratio, basal metabolic rate, and fasting insulin – higher alcohol drinking and lower education attainment, with increased EOCRC risk.Conclusion:Our novel findings indicate inherited susceptibility to EOCRC and suggest modifiable lifestyle and metabolic targets that could also be used to risk stratify individuals for personalized screening strategies or other interventions.<br/