A Nested Case-Control Study of Metabolically Defined Body Size Phenotypes and Risk of Colorectal Cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Obesity and the Risk of Gastrointestinal Cancers

Obesity is a risk factor for all major gastrointestinal cancers. With the rapid increase in the prevalence of obesity worldwide, this link could lead to an elevated burden of cancers of the digestive system. Currently, three main mechanisms explaining the link between excess adiposity and gastrointestinal cancer risk are being considered, including altered insulin signaling, obesity-associated chronic low-grade inflammation, and altered sex hormone metabolism, although new potential mechanisms emerge. This review is aimed to present our current knowledge on biological mechanisms involved in adiposity-related gastrointestinal carcinogenesis supported by results collected in epidemiological studies.

Adiposity and gastrointestinal cancers: epidemiology, mechanisms and future directions

Excess adiposity is a risk factor for several cancers of the gastrointestinal system, specifically oesophageal adenocarcinoma and colorectal, small intestine, pancreatic, liver, gallbladder and stomach cancers. With the increasing prevalence of obesity in nearly all regions of the world, this relationship could represent a growing source of cancers of the digestive system. Experimental and molecular epidemiological studies indicate important roles for alterations in insulin signalling, adipose tissue-derived inflammation and sex hormone pathways in mediating the association between adiposity and gastrointestinal cancer. The intestinal microbiome, gut hormones and non alcoholic fatty liver disease (NAFLD) also have possible roles. However, important gaps remain in our knowledge. For instance, our understanding of how adiposity throughout the life course is related to the risk of gastrointestinal cancer development and of how obesity influences gastrointestinal cancer prognosis and survival is limited. Nonetheless, the increasing use of state-of-the-art analytical methods (such as omics technologies, Mendelian randomization and MRI) in large-scale epidemiological studies offers exciting opportunities to advance our understanding of the complex relationship between adiposity and gastrointestinal cancers. Here, we examine the epidemiology of associations between obesity and gastrointestinal cancer, explore potential mechanisms underlying these relationships and highlight important unanswered research questions.

Influence of Obesity and Metabolic Abnormalities on the Risk of Developing Colorectal Neoplasia

BACKGROUND

Obesity and metabolic syndrome are risk factors for colorectal neoplasia (CRN). However, the association between metabolically healthy obese (MHO) or metabolically unhealthy non-obese (MUNO) status and the risk of CRN remains unclear.

AIMS

We aimed to elucidate the association between MHO or MUNO status and the risk of CRN.

METHODS

A total of 139,023 asymptomatic subjects who underwent a primary screening colonoscopy were categorized into 4 groups according to obesity and metabolic status: metabolically healthy non-obese (MHNO), MHO, MUNO, and metabolically unhealthy obese (MUO).

RESULTS

Mean participant age was 41.0 years, and the proportion of men was 65.3%. Among men, the risk of overall CRN increased in MHO (adjusted odds ratio [AOR] 1.22, 95% confidence intervals [CI] 1.12-1.33), MUNO (AOR 1.25, 95% CI 1.18-1.31), and MUO groups (AOR 1.47, 95% CI 1.40-1.54) compared with the MHNO group, whereas the risk of advanced CRN (ACRN) increased in MUNO (AOR 1.16, 95% CI 1.002-1.33) and MUO groups (AOR 1.49, 95% CI 1.31-1.70), but not in the MHO group (AOR 0.92, 95% CI 0.70-1.21). Moreover, among non-obese men, the risk of overall CRN and ACRN linearly increased with an increasing number of metabolic abnormalities. However, among women, only the MUO group had an increased risk of overall CRN (AOR 1.34, 95% CI 1.21-1.47) and no other significant associations were observed.

CONCLUSIONS

Poor metabolic health, regardless of obesity, is an independent risk factor for CRN in men. Our results suggest that men with metabolic abnormalities should be considered as a high-risk group for colorectal cancer, even if they are not obese.

Comorbidities, risk, and socioeconomic factors of uninsured cancer survivors

Cancer patients can be well-connected to resources during treatment but become lost to follow-up and subsequently may receive treatment in free clinics for chronic morbidities. Few studies have examined outcomes for uninsured patients with cancer histories in free clinics, but research examining socioeconomic determinants emphasizes poor cancer outcomes for patients with lower socioeconomic statuses (SES).Demographic data and chronic disease measures were extracted from medical charts of patients treated in 8 free clinics in 2016 in Tampa Bay. Descriptive statistics and Pearson correlation coefficients were used to demonstrate relationships between socioeconomic factors, cancer diagnoses, and comorbidities. Charlson Comorbidity Index (CCI) was used to assess mortality risk and severity of disease burden.The histories of 4804 uninsured patients were evaluated, identifying 86 (1.7%) as having had cancer. They were predominantly female (65.1%) and significantly older than those without cancer histories. Average duration from initial diagnosis was approximately 8.53 years (standard deviation [SD] 7.55). Overall, cancer patients had higher CCI scores (3.04 [1.928 SD] versus 0.90 [1.209 SD]; P <.001); thus reflecting more weighted comorbidities than patients without cancer (P <.001). Other factors of chronic disease including obesity and substance abuse correlated with cancer history.Among uninsured patients, those with cancer histories had greater mortality risk by CCI than those without. Chronic conditions such as diabetes, cerebrovascular disease, and chronic pulmonary disease existed in patients with cancer histories, affecting their mortality risk. Uninsured patients with a history of cancer are in greater need for chronic disease management and prevention.

Body size trajectories and cardio-metabolic resilience to obesity

Individuals with obesity do not represent a single homogenous group in terms of cardio‐metabolic health prospects. The concept of metabolically healthy obesity is a crude way of capturing this heterogeneity and has resulted in a plethora of research linking to future outcomes to show that it is not a benign condition. By contrast, very few studies have looked back in time and modelled the life course processes and exposures that explain the heterogeneity in cardio‐metabolic health and morbidity and mortality risk among people with the same body mass index (BMI) (or waist circumference or percentage body fat). The aim of the Medical Research Council New Investigator Research Grant (MR/P023347/1) ‘Body size trajectories and cardio‐metabolic resilience to obesity in three United Kingdom birth cohorts’ is to reveal the body size trajectories, pubertal development patterns and other factors (e.g. early‐life adversity) that might attenuate the positive associations of adulthood obesity makers (e.g. BMI) with cardio‐metabolic disease risk factors and other outcomes, thereby providing some degree of protection against the adverse effects of obesity. This work builds on the Principle Investigator's previous research as part of the Cohort and Longitudinal Studies Enhancement Resources initiative and focuses on secondary data analysis in the nationally representative UK birth cohort studies (initiated in 1946, 1958 and 1970), which have life course body size and exposure data and a biomedical sweep in adulthood. The grant will provide novel evidence on the life course processes and exposures that lead to some people developing a cardio‐metabolic complication or disease or dying while other people with the same BMI do not. This paper details the grant's scientific rationale, research objectives and potential impact.

Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment

BACKGROUND

Diabetes and high body-mass index (BMI) are associated with increased risk of several cancers, and are increasing in prevalence in most countries. We estimated the cancer incidence attributable to diabetes and high BMI as individual risk factors and in combination, by country and sex.

METHODS

We estimated population attributable fractions for 12 cancers by age and sex for 175 countries in 2012. We defined high BMI as a BMI greater than or equal to 25 kg/m2. We used comprehensive prevalence estimates of diabetes and BMI categories in 2002, assuming a 10-year lag between exposure to diabetes or high BMI and incidence of cancer, combined with relative risks from published estimates, to quantify contribution of diabetes and high BMI to site-specific cancers, individually and combined as independent risk factors and in a conservative scenario in which we assumed full overlap of risk of diabetes and high BMI. We then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. We also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and high BMI from 1980 to 2002. All analyses were done at individual country level and grouped by region for reporting.

FINDINGS

We estimated that 5·7% of all incident cancers in 2012 were attributable to the combined effects of diabetes and high BMI as independent risk factors, corresponding to 804 100 new cases. 187 600 (24·5%) of 766 000 cases of liver cancer and 121 700 (38·4%) of 317 000 cases of endometrial cancer were attributable to these risk factors. In the conservative scenario, about 4·5% (629 000 new cases) of all incident cancers assessed were attributable to diabetes and high BMI combined. Individually, high BMI (544 300 cases) was responsible for almost twice as many cancer cases as diabetes (293 300 cases). 25·8% of diabetes-related cancers (equating to 75 600 new cases) and 31·9% of high BMI-related cancers (174 040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.

INTERPRETATION

A substantial number of cancer cases are attributable to diabetes and high BMI. As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients.

FUNDING

NIHR and Wellcome Trust.

Circulating Metabolites Associated with Alcohol Intake in the European Prospective Investigation into Cancer and Nutrition Cohort

Identifying the metabolites associated with alcohol consumption may provide insights into the metabolic pathways through which alcohol may affect human health. We studied associations of alcohol consumption with circulating concentrations of 123 metabolites among 2974 healthy participants from the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Alcohol consumption at recruitment was self-reported through dietary questionnaires. Metabolite concentrations were measured by tandem mass spectrometry (BIOCRATES AbsoluteIDQTM p180 kit). Data were randomly divided into discovery (2/3) and replication (1/3) sets. Multivariable linear regression models were used to evaluate confounder-adjusted associations of alcohol consumption with metabolite concentrations. Metabolites significantly related to alcohol intake in the discovery set (FDR q-value < 0.05) were further tested in the replication set (Bonferroni-corrected p-value < 0.05). Of the 72 metabolites significantly related to alcohol intake in the discovery set, 34 were also significant in the replication analysis, including three acylcarnitines, the amino acid citrulline, four lysophosphatidylcholines, 13 diacylphosphatidylcholines, seven acyl-alkylphosphatidylcholines, and six sphingomyelins. Our results confirmed earlier findings that alcohol consumption was associated with several lipid metabolites, and possibly also with specific acylcarnitines and amino acids. This provides further leads for future research studies aiming at elucidating the mechanisms underlying the effects of alcohol in relation to morbid conditions.

Physical activity, sedentary behaviour and colorectal cancer risk in the UK Biobank

This corrects the article DOI: 10.1038/bjc.2017.85.

Metabolic obesity phenotypes and risk of colorectal cancer in postmenopausal women

Obesity has been postulated to increase the risk of colorectal cancer by mechanisms involving insulin resistance and the metabolic syndrome. We examined the associations of body mass index (BMI), waist circumference, the metabolic syndrome, metabolic obesity phenotypes and homeostasis model-insulin resistance (HOMA-IR-a marker of insulin resistance) with risk of colorectal cancer in over 21,000 women in the Women's Health Initiative CVD Biomarkers subcohort. Women were cross-classified by BMI (18.5-<25.0, 25.0-<30.0 and ≥30.0 kg/m² ) and presence of the metabolic syndrome into 6 phenotypes: metabolically healthy normal weight (MHNW), metabolically unhealthy normal weight (MUNW), metabolically healthy overweight (MHOW), metabolically unhealthy overweight (MUOW), metabolically healthy obese (MHO) and metabolically unhealthy obese (MUO). Neither BMI nor presence of the metabolic syndrome was associated with risk of colorectal cancer, whereas waist circumference showed a robust positive association. Relative to the MHNW phenotype, the MUNW phenotype was associated with increased risk, whereas no other phenotype showed an association. Furthermore, HOMA-IR was not associated with increased risk. Overall, our results do not support a direct role of metabolic dysregulation in the development of colorectal cancer; however, they do suggest that higher waist circumference is a risk factor, possibly reflecting the effects of increased levels of cytokines and hormones in visceral abdominal fat on colorectal carcinogenesis.

Separate and combined associations of obesity and metabolic health with coronary heart disease: a pan-European case-cohort analysis

Aims

The hypothesis of 'metabolically healthy obesity' implies that, in the absence of metabolic dysfunction, individuals with excess adiposity are not at greater cardiovascular risk. We tested this hypothesis in a large pan-European prospective study.

Methods and results

We conducted a case-cohort analysis in the 520 000-person European Prospective Investigation into Cancer and Nutrition study ('EPIC-CVD'). During a median follow-up of 12.2 years, we recorded 7637 incident coronary heart disease (CHD) cases. Using cut-offs recommended by guidelines, we defined obesity and overweight using body mass index (BMI), and metabolic dysfunction ('unhealthy') as ≥ 3 of elevated blood pressure, hypertriglyceridaemia, low HDL-cholesterol, hyperglycaemia, and elevated waist circumference. We calculated hazard ratios (HRs) and 95% confidence intervals (95% CI) within each country using Prentice-weighted Cox proportional hazard regressions, accounting for age, sex, centre, education, smoking, diet, and physical activity. Compared with metabolically healthy normal weight people (reference), HRs were 2.15 (95% CI: 1.79; 2.57) for unhealthy normal weight, 2.33 (1.97; 2.76) for unhealthy overweight, and 2.54 (2.21; 2.92) for unhealthy obese people. Compared with the reference group, HRs were 1.26 (1.14; 1.40) and 1.28 (1.03; 1.58) for metabolically healthy overweight and obese people, respectively. These results were robust to various sensitivity analyses.

Conclusion

Irrespective of BMI, metabolically unhealthy individuals had higher CHD risk than their healthy counterparts. Conversely, irrespective of metabolic health, overweight and obese people had higher CHD risk than lean people. These findings challenge the concept of 'metabolically healthy obesity', encouraging population-wide strategies to tackle obesity.

Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment

BACKGROUND

Diabetes and high body-mass index (BMI) are associated with increased risk of several cancers, and are increasing in prevalence in most countries. We estimated the cancer incidence attributable to diabetes and high BMI as individual risk factors and in combination, by country and sex.

METHODS

We estimated population attributable fractions for 12 cancers by age and sex for 175 countries in 2012. We defined high BMI as a BMI greater than or equal to 25 kg/m2. We used comprehensive prevalence estimates of diabetes and BMI categories in 2002, assuming a 10-year lag between exposure to diabetes or high BMI and incidence of cancer, combined with relative risks from published estimates, to quantify contribution of diabetes and high BMI to site-specific cancers, individually and combined as independent risk factors and in a conservative scenario in which we assumed full overlap of risk of diabetes and high BMI. We then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. We also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and high BMI from 1980 to 2002. All analyses were done at individual country level and grouped by region for reporting.

FINDINGS

We estimated that 5·6% of all incident cancers in 2012 were attributable to the combined effects of diabetes and high BMI as independent risk factors, corresponding to 792 600 new cases. 187 600 (24·5%) of 766 000 cases of liver cancer and 121 700 (38·4%) of 317 000 cases of endometrial cancer were attributable to these risk factors. In the conservative scenario, about 4·5% (626 900 new cases) of all incident cancers assessed were attributable to diabetes and high BMI combined. Individually, high BMI (544 300 cases) was responsible for twice as many cancer cases as diabetes (280 100 cases). 26·1% of diabetes-related cancers (equating to 77 000 new cases) and 31·9% of high BMI-related cancers (174 040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.

INTERPRETATION

A substantial number of cancer cases are attributable to diabetes and high BMI. As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients.

FUNDING

NIHR and Wellcome Trust.

Adult weight gain and colorectal adenomas-a systematic review and meta-analysis

Background

Colorectal adenomas are known as precursors for the majority of colorectal carcinomas. While weight gain during adulthood has been identified as a risk factor for colorectal cancer, the association is less clear for colorectal adenomas. We conducted a systematic review and meta-analysis to quantify the evidence on this association.

Methods

We searched Medline up to September 2016 to identify observational (prospective, cross-sectional and retrospective) studies on weight gain during adulthood and colorectal adenoma occurrence and recurrence. We conducted meta-analysis on high weight gain versus stable weight, linear and non-linear dose-response meta-analyses to analyze the association. Summary odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using a random effects model.

Results

For colorectal adenoma occurrence, the summary OR was 1.39 (95% CI: 1.17-1.65; I2: 43%, N = 9 studies, cases = 5507) comparing high (midpoint: 17.4 kg) versus stable weight gain during adulthood and with each 5 kg weight gain the odds increased by 7% (2%-11%; I2: 65%, N = 7 studies). Although there was indication of non-linearity (Pnon-linearity < 0.001) there was an increased odds of colorectal adenoma throughout the whole range of weight gain. Three studies were identified investigating the association between weight gain and colorectal adenoma recurrence and data were limited to draw firm conclusions.

Conclusions

Even a small amount of adult weight gain was related to a higher odds of colorectal adenoma occurrence. Our findings add to the benefits of weight control in adulthood regarding colorectal adenoma occurrence, which might be relevant for early prevention of colorectal cancer.

A Prospective Investigation of Body Size, Body Fat Composition and Colorectal Cancer Risk in the UK Biobank

Obesity has been consistently associated with a greater colorectal cancer risk, but this relationship is weaker among women. In the UK Biobank, we investigated the associations between body size (body mass index [BMI], height, waist circumference, and waist-to-hip ratio) and body fat composition (total body fat percentage and trunk fat percentage) measurements with colorectal cancer risk among 472,526 men and women followed for 5.6 years on average. Multivariable hazard ratios (HRs) and 95% confidence intervals (95%CI) for developing colorectal cancer (2,636 incident cases) were estimated using Cox proportional hazards models. Among men, when the highest and lowest fifths were compared, BMI (HR = 1.35, 95%CI: 1.13-1.61; Ptrend < 0.0001), waist circumference (HR = 1.66, 95%CI: 1.39-1.99; Ptrend < 0.0001), waist-to-hip ratio (HR = 1.58, 95%CI: 1.31-1.91; Ptrend < 0.0001), total body fat percentage (HR = 1.27, 95%CI: 1.06-1.53; Ptrend = 0.002), and trunk fat percentage (HR = 1.31, 95%CI: 1.09-1.58; Ptrend = 0.002) were associated with greater colorectal cancer risk. For women, only waist-to-hip ratio (HR for highest versus lowest fifth = 1.33, 95%CI: 1.08-1.65; Ptrend = 0.005) was positively associated with colorectal cancer risk. Greater body size (overall and abdominal adiposity) was positively associated with colorectal cancer development in men. For women, abdominal adiposity, rather than overall body size, was associated with a greater colorectal cancer risk.

Increasing colorectal cancer incidence trends among younger adults in Canada

Recent analyses in the United States have shown an overall decrease in the incidence of colorectal cancer despite contrasting increases in younger age groups. We examined whether these cohort trends are occurring in Canada. Age-specific trends in colon and rectal cancer incidence in Canada from the National Cancer Incidence Reporting System (1969-1992) and the Canadian Cancer Registry (1992-2012) were analyzed. We estimated annual percent changes (APC) with the Joinpoint Regression Program from the Surveillance Epidemiology, and End Results Program. Birth cohort effects were estimated using 5-year groups starting in 1888. Age-specific prevalence of class I, II and III obesity in Canada was examined from the National Population Health Survey (1994-2001) and the Canadian Community Health Survey (2001-2011). The reductions in CRC incidence among Canadians are limited to older populations. While reductions among younger age groups (20-29year olds (yo), 30-39yo and 40-50yo) were observed between 1969 and 1995, rates have returned to and surpassed historical levels (APCs 20-29yo colon cancer=6.24%, APCs 20-29yo rectal cancer=1.5%). Recent birth cohorts (1970-1990) have the highest incidence rate ratios ever recorded. Ecologic trends in obesity prevalence among these birth cohorts in Canada are suggestive of an impact on increasing incidence trends. Furthermore, obesity prevalence estimates suggest that these trends may continue to increase justifying further examination of the etiologic associations and biological impacts of excess adipose tissue among younger populations. While population-based screening of younger age groups deserves careful consideration, these concerning observed trends warrant public health action to address the growing obesity epidemic.

Obesity-related parameters and colorectal adenoma development

BACKGROUND

Obesity increases the risk of colorectal adenoma and colorectal cancer. However, the obesity-related parameters that are best for assessing the risk of colorectal adenoma development remain unclear. We analyzed the parameters that may best describe the association between obesity and colorectal adenoma development.

METHODS

In this retrospective cohort study, 3405 individuals underwent screening colonoscopy during routine health examinations. We measured body mass index; waist circumference; and metabolic parameters such as high-density lipoprotein-cholesterol, glucose, triglyceride, and systolic blood pressure. We analyzed the risk of developing colorectal adenoma, relative to obesity-related parameters, over a mean interval of 5.8 years from baseline colonoscopy.

RESULTS

In a multivariate analysis, waist circumference was the only obesity-related marker associated with an increased risk of metachronous colorectal adenoma. Men with waist circumferences ≥85 cm and women with waist circumference ≥82 cm had a 31% increased risk of metachronous colorectal adenoma compared to those with smaller waist circumferences [odds ratio (OR) 1.31; 95% confidence interval (CI, 1.09-1.57)]. Other factors associated with metachronous colorectal adenoma were age (OR, 1.03; 95% CI 1.02-1.04), male sex (OR 1.49; 95% CI 1.17-1.88), alcohol consumption ≥3/week (OR 1.33; 95% CI 1.10-1.62), the number of adenoma at baseline (OR 1.21; 95% CI 1.10-1.33), and the presence of advanced adenoma at baseline (OR 1.60; 95% CI 1.24-2.06).

CONCLUSIONS

Our findings suggest that central obesity, represented by waist circumference, is a significant predictor of metachronous colorectal adenoma, independent of body mass index and other metabolic variables.

Metabolic unhealthiness is an important predictor for the development of advanced colorectal neoplasia

Obesity is a well-known risk factor for colorectal neoplasia. Yet, the associations of both metabolic and obesity status with metachronous colorectal neoplasia remain unclear. We conducted a cohort study of 9,331 adults who underwent screening colonoscopy and surveillance colonoscopy. Participants were classified as metabolically healthy if they had no metabolic syndrome component. Participants were categorized into four groups according to body mass index and metabolic status: metabolically healthy non-obese (MHNO; n = 2,745), metabolically abnormal non-obese (MANO; n = 3,267), metabolically healthy obese (MHO; n = 707), and metabolically abnormal obese (MAO; n = 2,612). MAO individuals [n = 159 advanced colorectal neoplasia (AN) cases, 6.1%] and MANO individuals (n = 167 AN cases, 5.1%) had a higher incidence of AN compared with MHNO individuals (n = 79 AN cases, 2.9%). In a multivariable model, the risk of metachronous AN was higher in MANO (hazard ratio [HR] 1.43, 95% confidence interval [CI] 1.12–1.84) and MAO (HR 1.52, 95% CI 1.18–1.96) than in MHNO. In contrast, the risk of metachronous AN was not significantly elevated in MHO. In subgroup analyses, with or without adenoma at baseline, MAO was a risk group for metachronous AN, and MHO was not. Our findings suggest that metabolic unhealthiness is a significant predictor for metachronous AN.

Causes, Characteristics, and Consequences of Metabolically Unhealthy Normal Weight in Humans

A BMI in the normal range associates with a decreased risk of cardiometabolic disease and all-cause mortality. However, not all subjects in this BMI range have this low risk. Compared to people who are of normal weight and metabolically healthy, subjects who are of normal weight but metabolically unhealthy (∼20% of the normal weight adult population) have a greater than 3-fold higher risk of all-cause mortality and/or cardiovascular events. Here we address to what extent major risk phenotypes determine metabolic health in lean compared to overweight and obese people and provide support for the existence of a lipodystrophy-like phenotype in the general population. Furthermore, we highlight the molecular mechanisms that induce this phenotype. Finally, we propose strategies as to how this knowledge could be implemented in the prevention and treatment of cardiometabolic diseases in different stages of adiposity in routine clinical practice.

Obesity and Metabolic Unhealthiness Have Different Effects on Colorectal Neoplasms

CONTEXT

Obesity and insulin resistance are risk factors for colorectal neoplasms (CRN), but data regarding metabolic status, obesity, and CRN are lacking.

OBJECTIVE

To investigate the relationship between metabolic status, obesity, and CRN in Koreans who underwent colonoscopy.

DESIGN

Retrospective, cross-sectional.

PARTICIPANTS

Subjects were divided based on metabolic and obesity criteria, as follows: metabolically healthy nonobese (MHNO), metabolically healthy obese (MHO), metabolically unhealthy nonobese (MUNO), and metabolically unhealthy obese (MUO).

MAIN OUTCOME MEASURES

Multiple regression was used to identify CRN and advanced CRN risk factors, with the MHNO group as reference.

RESULTS

A total of 10,235 subjects was included, as follows: 5096 MHNO, 1538 MHO, 1746 MUNO, and 1855 MUO. Of these, 3297 had CRN (32.2%), and 434 (4.2%) had advanced CRN. Number of subjects with CRN in each group were: MHNO 25.8%, MHO 33.9%, MUNO 38.9%, and MUO 42.0% (P for trend < 0.001). Risk of CRN was increased in the MHO [odds ratio (OR) 1.239, 95% confidence interval (CI) 1.082 to 1.418, P = 0.002], the MUNO (OR 1.233, 95% CI 1.086 to 1.400, P = 0.001), and the MUO groups (OR 1.510, 95% CI 1.338 to 1.706, P < 0.001), whereas risk of advanced CRN was increased in the MUNO (OR 1.587, 95% CI 1.222 to 2.062, P = 0.001) and the MUO groups (OR 1.456, 95% CI 1.116 to 1.900, P = 0.006).

CONCLUSIONS

Obesity increased CRN risk with metabolically unhealthy status adding risk. For advanced CRN, metabolically unhealthy status increased the risk but obesity did not.

Metabolically-healthy obesity is associated with higher prevalence of colorectal adenoma

Background

The risk of colorectal adenoma (CRA), an important precursor of colorectal cancer, is largely unknown among obese individuals without obesity-related metabolic abnormalities, a condition described as metabolically-healthy obese (MHO). The aim of this study was to examine the association among metabolic status, the different categories of body mass index (BMI), and CRA in a large cohort of adults.

Methods

We analyzed the association among metabolic status, BMI categories and CRA in asymptomatic adults who underwent a first-time colonoscopy as part of the comprehensive health check-up program at the Health Promotion Center of Samsung Medical Center, from January 2005 to December 2012. Being metabolically healthy was defined as lacking any metabolic syndrome components and having a homeostasis model assessment of insulin resistance <2.5.

Results

The prevalence of “any,” “multiple,” and “high-risk” CRA was 25.6%, 8.3%, and 4.4% among 9,182 metabolically-healthy participants, and 35.9%, 12.5%, and 7.0% among 17,407 metabolically-unhealthy participants, respectively. Increased BMI showed a significant dose-dependent relationship with the prevalence of “any,” “multiple,” and “high-risk” CRA, in both metabolically-healthy and unhealthy participants. In multivariable-adjusted models that accounted for potential confounders including age, sex, smoking, alcohol, first-degree family history of colorectal cancer, and aspirin use, the odds ratio (OR) for any CRA comparing MHO with metabolically-healthy normal-weight (MHNW) participants was 1.25 (95% confidence interval (CI), 1.09–1.43). Further adjustment for metabolic components associated with obesity did not significantly change the association. Similarly, the ORs for multiple CRAs and high risk CRA were higher in MHO participants than MHNW participants [ORs (95% CI), 1.63 (1.31–2.04) and 1.53 (1.14–2.04), respectively].

Conclusions

The MHO phenotype was closely associated with higher prevalence of CRA, including high-risk adenoma. This finding supports the conclusion that MHO increases the risk of colorectal cancer.

2017 update on the relationship between diabetes and colorectal cancer: epidemiology, potential molecular mechanisms and therapeutic implications

Worldwide deaths from diabetes mellitus (DM) and colorectal cancer increased by 90% and 57%, respectively, over the past 20 years. The risk of colorectal cancer was estimated to be 27% higher in patients with type 2 DM than in non-diabetic controls. However, there are potential confounders, information from lower income countries is scarce, across the globe there is no correlation between DM prevalence and colorectal cancer incidence and the association has evolved over time, suggesting the impact of additional environmental factors. The clinical relevance of these associations depends on understanding the mechanism involved. Although evidence is limited, insulin use has been associated with increased and metformin with decreased incidence of colorectal cancer. In addition, colorectal cancer shares some cellular and molecular pathways with diabetes target organ damage, exemplified by diabetic kidney disease. These include epithelial cell injury, activation of inflammation and Wnt/β-catenin pathways and iron homeostasis defects, among others. Indeed, some drugs have undergone clinical trials for both cancer and diabetic kidney disease. Genome-wide association studies have identified diabetes-associated genes (e.g. TCF7L2) that may also contribute to colorectal cancer. We review the epidemiological evidence, potential pathophysiological mechanisms and therapeutic implications of the association between DM and colorectal cancer. Further studies should clarify the worldwide association between DM and colorectal cancer, strengthen the biological plausibility of a cause-and-effect relationship through characterization of the molecular pathways involved, search for specific molecular signatures of colorectal cancer under diabetic conditions, and eventually explore DM-specific strategies to prevent or treat colorectal cancer.

Metabolic Phenotype and Risk of Colorectal Cancer in Normal-Weight Postmenopausal Women

BACKGROUND

The prevalence of metabolically unhealthy phenotype in normal-weight adults is 30%, and few studies have explored the association between metabolic phenotype and colorectal cancer incidence in normal-weight individuals. Our aim was to compare the risk of colorectal cancer in normal-weight postmenopausal women who were characterized by either the metabolically healthy phenotype or the metabolically unhealthy phenotype.

METHODS

A large prospective cohort, the Women's Health Initiative, was used. The analytic sample included 5,068 postmenopausal women with BMI 18.5 to <25 kg/m2 Metabolic phenotype was defined using the Adult Treatment Panel-III definition, excluding waist circumference; therefore, women with one or none of the four components (elevated triglycerides, low high-density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose) were classified as metabolically healthy. Multivariable Cox proportional hazards regression was used to estimate adjusted HRs for the association between metabolic phenotype and risk of colorectal cancer.

RESULTS

Among normal-weight women, those who were metabolically unhealthy had higher risks of colorectal cancer (HR, 1.49; 95% CI, 1.02-2.18) compared with those who were metabolically healthy.

CONCLUSIONS

A metabolically unhealthy phenotype was associated with higher risk of colorectal cancer among normal-weight women.

IMPACT

Normal-weight women should still be evaluated for metabolic health and appropriate steps taken to reduce their risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 26(2); 155-61. ©2017 AACR.