Purpose: The association between the fecal microbiota and colorectal cancer (CRC) risk has been suggested in epidemiologic studies. However, data from large-scale population-based studies are lacking. Materials and Methods: In this case-control study, we recruited 283 CRC patients from the Center for Colorectal Cancer, National Cancer Center Hospital, Korea to perform 16S rRNA gene sequencing of fecal samples. A total of 283 age- and sex-matched healthy participants were selected from 890 cohort of healthy Koreans that are publicly available (PRJEB33905). The microbial dysbiosis index (MDI) was calculated based on the differentially abundant species. The association between MDI and CRC risk was observed using conditional logistic regression. Sparse Canonical Correlation Analysis was performed to integrate species data with microbial pathways obtained by PICRUSt2. Results: There is a significant divergence of the microbial composition between CRC patients and controls (permutational multivariate analysis of variance p=0.001). Those who were in third tertile of the MDI showed a significantly increased risk of CRC in the total population (odds ratio [OR], 6.93; 95% confidence interval [CI], 3.98 to 12.06; p-trend < 0.001) compared to those in the lowest tertile. Similar results were found for men (OR, 6.28; 95% CI, 3.04 to 12.98; p-trend < 0.001) and women (OR, 7.39; 95% CI, 3.10 to 17.63; p-trend < 0.001). Bacteroides coprocola and Bacteroides plebeius species and 12 metabolic pathways were interrelated in healthy controls that explain 91% covariation across samples. Conclusion Dysbiosis in the fecal microbiota may be associated with an increased risk of CRC. Due to the potentially modifiable nature of the gut microbiota, our findings may have implications for CRC prevention among Koreans.

The population attributable fraction (PAF) indicates the proportion of disease cases in a given population that can be attributed to a specific factor, assuming a causal relationship. In other words, it quantifies the extent to which that factor contributes to disease occurrence. PAF calculation methods have been applied to studies factors and several, studies have reported PAFs for dietary contributors to overall or specific cancer risks. Our team has conducted several PAF studies and presents findings on the contributions of dietary factors to cancer risk in the Korean population.Current Concepts: For colorectal cancer, the PAF of dietary factors is 34.9%, with insufficient whole grain intake contributing the largest share (16.6%). For gastric cancer, dietary factors have a PAF of 18.6%, with excessive intake of salted vegetables contributing the most (16.0%). Notably, the PAFs for inadequate whole grain and milk consumption were higher than those reported in previous studies, while the PAFs for other dietary factors fell within the expected range. These findings emphasize the need to prioritize interventions that effectively reduce the diet-attributable cancer burden.Discussion and Conclusion: Country-specific PAF estimates are crucial for developing effective cancer prevention strategies tailored to the Korean population. To better apply dietary PAF estimates, future studies should (1) integrate data from existing and ongoing cohort studies to determine Korea-specific relative risks, (2) estimate dietary prevalence using assessment tools that capture long-term dietary habits, and (3) establish optimal intake levels specific to the Korean context.

Purpose: The association between the fecal microbiota and colorectal cancer (CRC) risk has been suggested in epidemiologic studies. However, data from large-scale population-based studies are lacking. Materials and Methods: In this case-control study, we recruited 283 CRC patients from the Center for Colorectal Cancer, National Cancer Center Hospital, Korea to perform 16S rRNA gene sequencing of fecal samples. A total of 283 age- and sex-matched healthy participants were selected from 890 cohort of healthy Koreans that are publicly available (PRJEB33905). The microbial dysbiosis index (MDI) was calculated based on the differentially abundant species. The association between MDI and CRC risk was observed using conditional logistic regression. Sparse Canonical Correlation Analysis was performed to integrate species data with microbial pathways obtained by PICRUSt2. Results: There is a significant divergence of the microbial composition between CRC patients and controls (permutational multivariate analysis of variance p=0.001). Those who were in third tertile of the MDI showed a significantly increased risk of CRC in the total population (odds ratio [OR], 6.93; 95% confidence interval [CI], 3.98 to 12.06; p-trend < 0.001) compared to those in the lowest tertile. Similar results were found for men (OR, 6.28; 95% CI, 3.04 to 12.98; p-trend < 0.001) and women (OR, 7.39; 95% CI, 3.10 to 17.63; p-trend < 0.001). Bacteroides coprocola and Bacteroides plebeius species and 12 metabolic pathways were interrelated in healthy controls that explain 91% covariation across samples. Conclusion Dysbiosis in the fecal microbiota may be associated with an increased risk of CRC. Due to the potentially modifiable nature of the gut microbiota, our findings may have implications for CRC prevention among Koreans.

The population attributable fraction (PAF) indicates the proportion of disease cases in a given population that can be attributed to a specific factor, assuming a causal relationship. In other words, it quantifies the extent to which that factor contributes to disease occurrence. PAF calculation methods have been applied to studies factors and several, studies have reported PAFs for dietary contributors to overall or specific cancer risks. Our team has conducted several PAF studies and presents findings on the contributions of dietary factors to cancer risk in the Korean population.Current Concepts: For colorectal cancer, the PAF of dietary factors is 34.9%, with insufficient whole grain intake contributing the largest share (16.6%). For gastric cancer, dietary factors have a PAF of 18.6%, with excessive intake of salted vegetables contributing the most (16.0%). Notably, the PAFs for inadequate whole grain and milk consumption were higher than those reported in previous studies, while the PAFs for other dietary factors fell within the expected range. These findings emphasize the need to prioritize interventions that effectively reduce the diet-attributable cancer burden.Discussion and Conclusion: Country-specific PAF estimates are crucial for developing effective cancer prevention strategies tailored to the Korean population. To better apply dietary PAF estimates, future studies should (1) integrate data from existing and ongoing cohort studies to determine Korea-specific relative risks, (2) estimate dietary prevalence using assessment tools that capture long-term dietary habits, and (3) establish optimal intake levels specific to the Korean context.

Purpose: The association between the fecal microbiota and colorectal cancer (CRC) risk has been suggested in epidemiologic studies. However, data from large-scale population-based studies are lacking. Materials and Methods: In this case-control study, we recruited 283 CRC patients from the Center for Colorectal Cancer, National Cancer Center Hospital, Korea to perform 16S rRNA gene sequencing of fecal samples. A total of 283 age- and sex-matched healthy participants were selected from 890 cohort of healthy Koreans that are publicly available (PRJEB33905). The microbial dysbiosis index (MDI) was calculated based on the differentially abundant species. The association between MDI and CRC risk was observed using conditional logistic regression. Sparse Canonical Correlation Analysis was performed to integrate species data with microbial pathways obtained by PICRUSt2. Results: There is a significant divergence of the microbial composition between CRC patients and controls (permutational multivariate analysis of variance p=0.001). Those who were in third tertile of the MDI showed a significantly increased risk of CRC in the total population (odds ratio [OR], 6.93; 95% confidence interval [CI], 3.98 to 12.06; p-trend < 0.001) compared to those in the lowest tertile. Similar results were found for men (OR, 6.28; 95% CI, 3.04 to 12.98; p-trend < 0.001) and women (OR, 7.39; 95% CI, 3.10 to 17.63; p-trend < 0.001). Bacteroides coprocola and Bacteroides plebeius species and 12 metabolic pathways were interrelated in healthy controls that explain 91% covariation across samples. Conclusion Dysbiosis in the fecal microbiota may be associated with an increased risk of CRC. Due to the potentially modifiable nature of the gut microbiota, our findings may have implications for CRC prevention among Koreans.

The population attributable fraction (PAF) indicates the proportion of disease cases in a given population that can be attributed to a specific factor, assuming a causal relationship. In other words, it quantifies the extent to which that factor contributes to disease occurrence. PAF calculation methods have been applied to studies factors and several, studies have reported PAFs for dietary contributors to overall or specific cancer risks. Our team has conducted several PAF studies and presents findings on the contributions of dietary factors to cancer risk in the Korean population.Current Concepts: For colorectal cancer, the PAF of dietary factors is 34.9%, with insufficient whole grain intake contributing the largest share (16.6%). For gastric cancer, dietary factors have a PAF of 18.6%, with excessive intake of salted vegetables contributing the most (16.0%). Notably, the PAFs for inadequate whole grain and milk consumption were higher than those reported in previous studies, while the PAFs for other dietary factors fell within the expected range. These findings emphasize the need to prioritize interventions that effectively reduce the diet-attributable cancer burden.Discussion and Conclusion: Country-specific PAF estimates are crucial for developing effective cancer prevention strategies tailored to the Korean population. To better apply dietary PAF estimates, future studies should (1) integrate data from existing and ongoing cohort studies to determine Korea-specific relative risks, (2) estimate dietary prevalence using assessment tools that capture long-term dietary habits, and (3) establish optimal intake levels specific to the Korean context.

Background: The increasing rate of excess body weight (EBW) in the global population has led to growing health concerns, including cancer-related EBW. We aimed to estimate the population attributable fraction (PAF) of cancer incidence and deaths linked to EBW in Korean individuals from 2015 to 2030 and to compare its value with various body mass index cutoffs. Methods: Levin’s formula was used to calculate the PAF; the prevalence rates were computed using the Korean National Health and Nutrition Examination Survey data, while the relative risks of specific cancers related to EBW were estimated based on the results of Korean cohort studies. To account for the 15-year latency period when estimating the PAF in 2020, the prevalence rates from 2015 and attributable cases or deaths from 2020 were used. Results: The PAF attributed to EBW was similar for both cancer incidence and deaths using either the World Health Organization (WHO) Asian-Pacific region standard or a modified Asian standard, with the WHO standard yielding the lowest values. In the Korean population, the PAFs of EBW for cancer incidence were 2.96% in men and 3.61% in women, while those for cancer deaths were 0.67% in men and 3.06% in women in 2020. Additionally, PAFs showed a gradual increase in both sexes until 2030. Conclusion The EBW continues to have a significant impact on cancer incidence and deaths in Korea. Effective prevention strategies targeting the reduction of this modifiable risk factor can substantially decrease the cancer burden.

OBJECTIVES: Mercury can stimulate immune responses through T helper 17 (Th17). The gene IL23R is a key factor in Th17 function, which may also contribute to digestive tract diseases. The aim of this study was to identify the associations between dietary mercury and gastric cancer (GC) and to investigate whether the IL23R rs10889677 polymorphism modifies those associations. METHODS: This case-control study included 377 patients with GC and 756 healthy controls. Dietary mercury intake (total mercury and methylmercury) was assessed using a dietary heavy metal database incorporated into the food frequency questionnaire. IL23R genetic polymorphism rs10889677 (A>C) was genotyped. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression models with adjustments for potential confounders. RESULTS: A higher dietary methylmercury intake was associated with an elevated risk of GC (OR for the highest vs. lowest tertile [T3 vs. T1], 2.02; 95% CI, 1.41 to 2.91; p for trend <0.001). The IL23R rs10889677 reduced the risk of GC in individuals who carried at least 1 minor allele (OR, 0.62; 95% CI, 0.46 to 0.83; p=0.001; AC/CC vs. AA). Individuals with a C allele exhibited a lower susceptibility to GC through methylmercury intake than those with the AA genotype (OR for the T3 of methylmercury and AA carriers, 2.93; 95% CI, 1.77 to 4.87; and OR for the T3 of methylmercury and AC/CC genotype, 1.30; 95% CI, 0.76 to 2.21; p-interaction=0.013). CONCLUSIONS Our findings suggest that a genetic polymorphism, rs10889677 in IL23R, plays a role in modifying the association between dietary methylmercury intake and the risk of GC.

Background: The increasing rate of excess body weight (EBW) in the global population has led to growing health concerns, including cancer-related EBW. We aimed to estimate the population attributable fraction (PAF) of cancer incidence and deaths linked to EBW in Korean individuals from 2015 to 2030 and to compare its value with various body mass index cutoffs. Methods: Levin’s formula was used to calculate the PAF; the prevalence rates were computed using the Korean National Health and Nutrition Examination Survey data, while the relative risks of specific cancers related to EBW were estimated based on the results of Korean cohort studies. To account for the 15-year latency period when estimating the PAF in 2020, the prevalence rates from 2015 and attributable cases or deaths from 2020 were used. Results: The PAF attributed to EBW was similar for both cancer incidence and deaths using either the World Health Organization (WHO) Asian-Pacific region standard or a modified Asian standard, with the WHO standard yielding the lowest values. In the Korean population, the PAFs of EBW for cancer incidence were 2.96% in men and 3.61% in women, while those for cancer deaths were 0.67% in men and 3.06% in women in 2020. Additionally, PAFs showed a gradual increase in both sexes until 2030. Conclusion The EBW continues to have a significant impact on cancer incidence and deaths in Korea. Effective prevention strategies targeting the reduction of this modifiable risk factor can substantially decrease the cancer burden.

OBJECTIVES: Mercury can stimulate immune responses through T helper 17 (Th17). The gene IL23R is a key factor in Th17 function, which may also contribute to digestive tract diseases. The aim of this study was to identify the associations between dietary mercury and gastric cancer (GC) and to investigate whether the IL23R rs10889677 polymorphism modifies those associations. METHODS: This case-control study included 377 patients with GC and 756 healthy controls. Dietary mercury intake (total mercury and methylmercury) was assessed using a dietary heavy metal database incorporated into the food frequency questionnaire. IL23R genetic polymorphism rs10889677 (A>C) was genotyped. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression models with adjustments for potential confounders. RESULTS: A higher dietary methylmercury intake was associated with an elevated risk of GC (OR for the highest vs. lowest tertile [T3 vs. T1], 2.02; 95% CI, 1.41 to 2.91; p for trend <0.001). The IL23R rs10889677 reduced the risk of GC in individuals who carried at least 1 minor allele (OR, 0.62; 95% CI, 0.46 to 0.83; p=0.001; AC/CC vs. AA). Individuals with a C allele exhibited a lower susceptibility to GC through methylmercury intake than those with the AA genotype (OR for the T3 of methylmercury and AA carriers, 2.93; 95% CI, 1.77 to 4.87; and OR for the T3 of methylmercury and AC/CC genotype, 1.30; 95% CI, 0.76 to 2.21; p-interaction=0.013). CONCLUSIONS Our findings suggest that a genetic polymorphism, rs10889677 in IL23R, plays a role in modifying the association between dietary methylmercury intake and the risk of GC.