Metabolic Mediators of the Association Between Adult Weight Gain and Colorectal Cancer: Data From the European Prospective Investigation into Cancer and Nutrition (EPIC) Cohort

Importance of circulating leptin and adiponectin in the causal pathways between obesity and the development of colorectal cancer in Japanese men

BACKGROUND

The mechanistic associations between obesity and risk of colorectal cancer (CRC) remain unclear. Here, using body mass index (BMI) as an obesity indicator, we decomposed the total effects of obesity on the risk of CRC into: (1) direct effects, which are possibly mediated by unmeasured or currently unknown factors; (2) indirect effects mediated by circulating leptin and adiponectin; and (3) indirect effects that are not mediated by circulating leptin and adiponectin but by hyperinsulinemia and chronic inflammation (assessed via circulating connecting peptide and C-reactive protein, respectively).

METHODS

We adopted a causal mediation framework, using data from a large prospective cohort study of 44,271 Japanese men.

RESULTS

BMI was not associated with the risk of CRC due to direct and indirect effects that were not mediated by circulating leptin and adiponectin. By contrast, individuals with BMIs of 25.0-27.4 kg/m2 (risk ratio, 1.29; 95% confidence interval, 0.98-1.69) and ≥27.5 kg/m2 (risk ratio, 1.28; 95% confidence interval, 0.98-1.68) had a higher risk of CRC due to indirect effects of circulating leptin and adiponectin.

CONCLUSIONS

Our mediation analyses suggest that the association between BMI and CRC risk may be largely mediated by a pathway involving circulating leptin and adiponectin.

Identification of potential mediators of the relationship between body mass index and colorectal cancer: a Mendelian randomization analysis

BACKGROUND

Colorectal cancer (CRC) is the third-most-common cancer worldwide and its rates are increasing. Elevated body mass index (BMI) is an established risk factor for CRC, although the molecular mechanisms behind this association remain unclear. Using the Mendelian randomization (MR) framework, we aimed to investigate the mediating effects of putative biomarkers and other CRC risk factors in the association between BMI and CRC.

METHODS

We selected as mediators biomarkers of established cancer-related mechanisms and other CRC risk factors for which a plausible association with obesity exists, such as inflammatory biomarkers, glucose homeostasis traits, lipids, adipokines, insulin-like growth factor 1 (IGF1), sex hormones, 25-hydroxy-vitamin D, smoking, physical activity (PA) and alcohol consumption. We used inverse-variance weighted MR in the main univariable analyses and performed sensitivity analyses (weighted-median, MR-Egger, Contamination Mixture). We used multivariable MR for the mediation analyses.

RESULTS

Genetically predicted BMI was positively associated with CRC risk [odds ratio per SD (5 kg/m2) = 1.17, 95% CI: 1.08-1.24, P-value = 1.4 × 10-5] and robustly associated with nearly all potential mediators. Genetically predicted IGF1, fasting insulin, low-density lipoprotein cholesterol, smoking, PA and alcohol were associated with CRC risk. Evidence for attenuation was found for IGF1 [explained 7% (95% CI: 2-13%) of the association], smoking (31%, 4-57%) and PA (7%, 2-11%). There was little evidence for pleiotropy, although smoking was bidirectionally associated with BMI and instruments were weak for PA.

CONCLUSIONS

The effect of BMI on CRC risk is possibly partly mediated through plasma IGF1, whereas the attenuation of the BMI-CRC association by smoking and PA may reflect confounding and shared underlying mechanisms rather than mediation.

[Obesity and Colorectal Cancer]

The prevalence of obesity has increased significantly worldwide, and this trend is likely to continue in the coming years. There is substantial evidence that obesity plays a crucial role in the development of colorectal cancer. Epidemiological data have consistently demonstrated a correlation between obesity and colorectal cancer. Insulin resistance, hyperinsulinemia, chronic inflammation, altered levels of growth factors, adipocytokines, and various hormones are plausible biological mechanisms. In addition, obesity has been shown to have an impact on recurrence, treatment success, and overall survival. There are some reports, although the evidence is not conclusive, that weight loss and lifestyle changes such as dietary modification and physical activity can reduce the risk of colorectal cancer. The understanding that obesity is a potentially modifiable risk factor that can affect the incidence and prognosis of colorectal cancer is crucial knowledge that can have an impact on the prevention and treatment of the condition.

Metabolic Risk Factors Associated with Early-Onset Colorectal Adenocarcinoma: A Case-Control Study at Kaiser Permanente Southern California

BACKGROUND

The incidence of early-onset colorectal cancer (eoCRC) diagnosed among individuals under age 50 has been rising. However, risk factors for eoCRC are unclear. We investigated whether metabolic abnormalities are risk factors for eoCRC adenocarcinoma.

METHODS

Invasive colorectal adenocarcinoma cases diagnosed between ages 15 and 49 from 2008 to 2018 at Kaiser Permanente Southern California (KPSC) were identified. Those with a history of inflammatory bowel disease were excluded. Noncancer controls were selected 5:1 for each case matched by age, sex, and length of membership prior to index date. Data were collected from KSPC's electronic medical records. The exposures of interest included obesity, type II diabetes, hypertension, and dyslipidemia, assessed from ≥1 year prior to eoCRC diagnosis/index date. Conditional logistic regressions were used to evaluate the associations between these metabolic risk factors and risk of eoCRC adenocarcinoma, adjusting for race/ethnicity, smoking, family history, neighborhood socioeconomic status, and health care utilization.

RESULTS

A total of 1,032 cases and 5,128 controls were included. Risk of colorectal adenocarcinoma was significantly associated with obesity [odds ratio (OR) = 1.41; 95% confidence interval (CI), 1.15-1.74], but not diabetes, hypertension or dyslipidemia. In analysis stratified by tumor location, obesity was significantly associated with risk of colon adenocarcinoma OR = 1.56 (1.17-2.07), but its association with rectal adenocarcinoma was less clear OR = 1.19 (0.85-1.68). No significant interaction was detected between obesity and age (≥40 vs. <40), and obesity and sex.

CONCLUSIONS

Obesity was associated with risk for eoCRC adenocarcinoma.

IMPACT

This finding could help inform early-onset colorectal adenocarcinoma screening and prevention recommendations.See related commentary by Hayes, p. xxx.

Association of circulating leptin and adiponectin levels with colorectal cancer risk: A systematic review and meta-analysis of case-control studies

PURPOSE

Leptin and adiponectin are adipokines which have been commonly implicated in carcinogenesis. As such, many studies have investigated the association of circulating leptin and adiponectin levels with colorectal cancer (CRC) risk. However, the results remained inconsistent.

METHODS

In this work, we performed a systematic review and meta-analysis to precisely examine the association between circulating levels of leptin and adiponectin and CRC risk. A systematic literature search was performed in PubMed/MEDLINE, Scopus, Web of Science, and EMBASE databases from inception until October 2020. The pooled effect size was then estimated by calculating the odds ratio (OR).

RESULTS

A total of 23 records (comprising 26 studies) were included in the meta-analysis. The overall analysis found that circulating levels of leptin and adiponectin were not significantly associated with CRC risk (P > 0.05). Interestingly, subgroup analysis revealed that a higher level of adiponectin was significantly associated with an increased CRC risk among overweight individuals (OR = 1.16; 95 % CI: 1.02, 1.32), and a decreased CRC risk among normal weight individuals (OR = 0.76; 95 % CI: 0.62, 0.92). Besides, a higher level of adiponectin was also significantly associated with a decreased risk of CRC in men (OR = 0.76; 95 % CI: 0.59, 0.98).

CONCLUSIONS

In conclusion, circulating leptin level was not associated with CRC risk, but that of adiponectin was associated with CRC risk only in specific subgroups.

Colorectal Cancer among Resettlers from the Former Soviet Union and in the General German Population: Clinical and Pathological Characteristics and Trends

This study examined time trends and clinical and pathological characteristics of colorectal cancer (CRC) among ethnic German migrants from the Former Soviet Union (resettlers) and the general German population. Incidence data from two population-based cancer registries were used to analyze CRC as age-standardized rates (ASRs) over time. The respective general populations and resettler cohorts were used to calculate standardized incidence ratios (SIRs) by time-period (before and after the introduction of screening colonoscopy in 2002), tumor location, histologic type, grade, and stage at diagnosis. Additionally, SIRs were modeled with Poisson regression to depict time trends. During the study period from 1990 to 2013, the general populations showed a yearly increase of ASR, but for age above 55, truncated ASR started to decline after 2002. Among resettlers, 229 CRC cases were observed, resulting in a lowered incidence for all clinical and pathological characteristics compared to the general population (overall SIR: 0.78, 95% CI 0.68–0.89). Regression analysis revealed an increasing SIR trend after 2002. Population-wide CRC incidence decreases after the introduction of screening colonoscopy. In contrast the lowered CRC incidence among resettlers is attenuating to the general population after 2002, suggesting that resettlers do not benefit equally from screening colonoscopy.

Genetically determined elevated C-reactive protein associated with primary colorectal cancer risk: Mendelian randomization with lifestyle interactions

Systemic inflammation-related etiologic pathways via inflammatory cytokines in the development of colorectal cancer (CRC) have not been convincingly determined and may be confounded by lifestyle factors or reverse causality. We investigated the genetically predicted C-reactive protein (CRP) phenotype in the potential causal pathway of primary CRC risk in postmenopausal women in a Mendelian randomization (MR) framework. We employed individual-level data of the Women's Health Initiative Database for Genotypes and Phenotypes Study, which consists of 5 genome-wide association (GWA) studies, including 10,142 women, 737 of whom developed primary CRC. We examined 61 GWA single-nucleotide polymorphisms (SNPs) associated with CRP by using weighted/penalized MR weighted-medians and MR gene-environment interactions that allow some relaxation of the strict variable requirements and attenuate the heterogeneous estimates of outlying SNPs. In lifestyle-stratification analyses, genetically determined CRP exhibited its effects on the decreased CRC risk in non-viscerally obese and high-fat diet subgroups. In contrast, genetically driven CRP was associated with an increased risk for CRC in women who smoked ≥ 15 cigarettes/day, with significant interaction of the gene-smoking relationship. Further, a substantially increased risk of CRC induced by CRP was observed in relatively short-term users (< 5 years) of estrogen (E)-only and also longer-term users (5 to > 10 years) of E plus progestin. Our findings may provide novel evidence on immune-related etiologic pathways connected to CRC risk and suggest the possible use of CRP as a CRC-predictive biomarker in women with particular behaviors and CRP marker-informed interventions to reduce CRC risk.

Development and validation of a lifestyle-based model for colorectal cancer risk prediction: the LiFeCRC score

BACKGROUND

Nutrition and lifestyle have been long established as risk factors for colorectal cancer (CRC). Modifiable lifestyle behaviours bear potential to minimize long-term CRC risk; however, translation of lifestyle information into individualized CRC risk assessment has not been implemented. Lifestyle-based risk models may aid the identification of high-risk individuals, guide referral to screening and motivate behaviour change. We therefore developed and validated a lifestyle-based CRC risk prediction algorithm in an asymptomatic European population.

METHODS

The model was based on data from 255,482 participants in the European Prospective Investigation into Cancer and Nutrition (EPIC) study aged 19 to 70 years who were free of cancer at study baseline (1992-2000) and were followed up to 31 September 2010. The model was validated in a sample comprising 74,403 participants selected among five EPIC centres. Over a median follow-up time of 15 years, there were 3645 and 981 colorectal cancer cases in the derivation and validation samples, respectively. Variable selection algorithms in Cox proportional hazard regression and random survival forest (RSF) were used to identify the best predictors among plausible predictor variables. Measures of discrimination and calibration were calculated in derivation and validation samples. To facilitate model communication, a nomogram and a web-based application were developed.

RESULTS

The final selection model included age, waist circumference, height, smoking, alcohol consumption, physical activity, vegetables, dairy products, processed meat, and sugar and confectionary. The risk score demonstrated good discrimination overall and in sex-specific models. Harrell's C-index was 0.710 in the derivation cohort and 0.714 in the validation cohort. The model was well calibrated and showed strong agreement between predicted and observed risk. Random survival forest analysis suggested high model robustness. Beyond age, lifestyle data led to improved model performance overall (continuous net reclassification improvement = 0.307 (95% CI 0.264-0.352)), and especially for young individuals below 45 years (continuous net reclassification improvement = 0.364 (95% CI 0.084-0.575)).

CONCLUSIONS

LiFeCRC score based on age and lifestyle data accurately identifies individuals at risk for incident colorectal cancer in European populations and could contribute to improved prevention through motivating lifestyle change at an individual level.

Linking Obesity with Colorectal Cancer: Epidemiology and Mechanistic Insights

The incidence of obesity and colorectal cancer (CRC) has risen rapidly in recent decades. More than 650 million obese and 2 billion overweight individuals are currently living in the world. CRC is the third most common cancer. Obesity is regarded as one of the key environmental risk factors for the pathogenesis of CRC. In the present review, we mainly focus on the epidemiology of obesity and CRC in the world, the United States, and China. We also summarize the molecular mechanisms linking obesity to CRC in different aspects, including nutriology, adipokines and hormones, inflammation, gut microbiota, and bile acids. The unmet medical needs for obesity-related CRC are still remarkable. Understanding the molecular basis of these associations will help develop novel therapeutic targets and approaches for the treatment of obesity-related CRC.

Increased 30-Day Mortality Risk in Patients With Diabetes Mellitus After Colon Cancer Surgery: A Mediation Analysis

BACKGROUND

Patients with (versus without) diabetes mellitus who develop colon cancer are at increased risk of dying within 30 days after surgery.

OBJECTIVE

The purpose of this study was to identify potential mediators of the effect of diabetes mellitus on all-cause 30-day mortality risk after surgery for colon cancer.

DESIGN

A retrospective cohort study was conducted using the 2013-2015 National Surgical Quality Improvement Program data.

SETTING

The study was conducted at various hospitals across the United States (from 435 to 603 hospitals).

PATIENTS

Patients who underwent resection for colon cancer with or without obstruction based on the National Surgical Quality Improvement Program colectomy module were included. Patients who had ASA physical status classification V or metastatic disease and those who presented emergently were excluded. Patients were classified as "no diabetes," "diabetes not requiring insulin," or "diabetes requiring insulin." Potential reasons for increased risk of dying within 30 days were treatment related, comorbidity, health behaviors, surgical complications, and biomarkers of underlying disease.

MAIN OUTCOME MEASURES

We measured all-cause 30-day mortality.

RESULTS

Of 26,060 patients, 18.8% (n = 4905) had diabetes mellitus that was treated with insulin (n = 1595) or other antidiabetic agents (n = 3340). Patients with diabetes mellitus had a 1.57 (95% CI, 1.23-1.99) higher unadjusted odds of dying within 30 days versus patients without diabetes mellitus. In the multivariable model, 76.7% of the association between diabetes mellitus and 30-day mortality was explained; patients with diabetes mellitus were equally likely to die within 30 days versus those without diabetes mellitus (OR = 1.05 (95% CI, 0.81-1.35)). Anemia and sepsis explained 33.7% and 15.2% of the effect of diabetes mellitus on 30-day mortality (each p < 0.0001). Treatment-related variables, cardiovascular disease, surgical complications, and biomarkers played limited roles as mediators.

LIMITATIONS

The study was limited to larger hospitals, and limited information about duration and type of diabetes mellitus was available.

CONCLUSIONS

Better management and prevention of anemia and sepsis among patients with diabetes mellitus may reduce their increased risk of death after colon cancer resection. See Video Abstract at http://links.lww.com/DCR/B140. AUMENTO DEL RIESGO DE MORTALIDAD A 30 DÍAS EN PACIENTES DIABETICOS LUEGO DE CIRUGÍA DE CÁNCER DE COLON: ANÁLISIS DE MEDIACIÓN: Los pacientes con (y sin) diabetes que desarrollan cáncer de colon tienen un mayor riesgo de morir dentro de los 30 días posteriores a la cirugía.Identificar los posibles mediadores del efecto de la diabetes sobre el riesgo de mortalidad dentro los 30 días, por cualquier causa después de cirugía por cáncer de colon.Estudio de cohortes retrospectivo entre 2013-2015 utilizando los datos del Programa Nacional de Mejoría en Calidad Quirúrgica.Entre 435 a 603 hospitales en los Estados Unidos.Se incluyeron aquellos pacientes sometidos a resección por cáncer de colon con o sin obstrucción según el módulo de colectomía Programa Nacional de Mejoría en Calidad Quirúrgica. Se excluyeron los pacientes estadío V de la clasificación de la Sociedad Estadounidense de Anestesiólogos (ASA), aquellos con enfermedad metastásica y aquellos operados de urgencia. Los pacientes se clasificaron como "sin diabetes,' "con diabetes que no requiere insulina" o "con diabetes que requiere insulina.' Las posibles razones para un mayor riesgo de morir dentro de los 30 días estuvieron relacionadas con el tratamiento, la comorbilidad, los comportamientos de salud, las complicaciones quirúrgicas y los biomarcadores de enfermedad.Mortalidad de cualquier orígen dentro los 30 días depués de la cirugía.De 26'060 pacientes, 18.8% (n = 4,905) tenían diabetes tratada con insulina (n = 1,595) u otros agentes antidiabéticos (n = 3,340). Los pacientes con diabetes tenían 1.57 (IC 95%: 1.23-1.99) mayores probabilidades no ajustadas de morir dentro de los 30 días en comparación con los pacientes sin diabetes. En el modelo multivariable, se explicó que el 76,7% de la asociación entre diabetes y mortalidad a los 30 días; los pacientes con diabetes tenían la misma probabilidad de morir dentro de los 30 días que aquellos sin diabetes (OR: 1.05; IC 95%: 0.81-1.35). La anemia y la sepsis explicaron el 33,7% y el 15,2% del efecto de la diabetes en la mortandad a 30 días (p <0,0001). Las variables relacionadas con el tratamiento, las enfermedades cardiovasculares, las complicaciones quirúrgicas y los biomarcadores jugaron un papel limitado como mediadores.Estudio limitado a hospitales más grandes e información limitada sobre la duración y el tipo de diabetes.Una mejor prevención y manejo de la anemia y la sepsis en los pacientes con diabetes puede reducir el mayor riesgo de muerte después de la resección del cáncer de colon. Consulte Video Resumen en http://links.lww.com/DCR/B140.

Leptin and adiponectin dynamics at patients with rectal neoplasm - Gender differences

Background

Numerous studies associate adipokines with colorectal malignancy, but few data deal with patients suffering exclusively of rectal carcinoma (RC).

Aims

We evaluated leptin and adiponectin levels in RC patients compared to healthy population and their dynamics after surgery.

Material and methods

Serum leptin and adiponectin were evaluated before surgery in 59 RC consecutive patients (38 males and 21 females), and in age and weight matched healthy controls. Measurements were repeated at 24, 72 hours and 7 days after surgery.

Results

Adipokine levels were higher in women. Controls had higher leptin (32.±4.34 vs 9.51±1.73 ng/ml in women and 11±2.66 vs 2.54±0.39 ng/ml in men, p = 0.00048 and 0.0032) and lower adiponectin (9±0.64 vs 11.85±1.02 μg/ml in women and 7.39±0.51 vs 8.5±0.62 μg/ml in men, p = 0.017 and 0.019) than RC patients. Surgery caused an increase of leptin from 5.11±0.8 to 18.7±2.42 ng/ml, p = 6.85 x 10¨⁸, and a decrease of adiponectin from 9.71±0.58 to 7.87±0.47 μg/ml, p = 1.4 x 10¨¹⁰ for all RC patients and returned thereafter to the initial range at 7 days. Adipokines were correlated with body weight (BW). The significance of correlation persisted after surgery only in males, but disappeared in females. Adipokines were not modified by tumor position, presurgical chemoradiotherapy or surgical technique. Women with RC experiencing weight loss had higher adiponectin than women without weight modifications (p<0.05 at all time points).

Conclusions

Adipokine levels of patients with RC differ from the healthy population, possibly reflecting an adaptation to disease. Adipokine modifications after surgery may be related to acute surgical stress. Whether leptin and adiponectin directly interact is not clear. Women have higher adipokine levels, more so after significant weight loss, but the strength of their correlation with BW decreases after surgery. These data suggest gender differences in the adipokine profile of RC patients which may find clinical applications.

VARIATIONS OF ADIPOKINE PROFILE IN PATIENTS DIAGNOSED WITH RECTAL CARCINOMA

BACKGROUND

Adipokine secretion is influenced by various disease conditions.

PURPOSE

We wanted to check the impact of rectal carcinoma (RC) on adipokine profile.

PATIENTS AND METHODS

We evaluated serum leptin and adiponectin levels in 24 RC patients (12 males and 12 females) as well as in the same number of age, sex and weight-matched healthy controls.

RESULTS

Adipokines were oppositely correlated with body weight (BW) in controls and RC patients. Women had higher adipokine levels than men. Healthy controls had higher leptin (37.6.±7.8 vs. 7.9±2.6 ng/mL in women and 11.9±4.6 vs. 1.4±0.34 ng/mL in men, p=0.0016 and 0.043) and lower adiponectin levels (9.3±1.1 vs. 14.9±1.1 µg/mL in women and 7.9±0.9 vs. 11.1±0.9 µg/mL in men, p=0.012 and 0.017) than RC patients.

CONCLUSION

Adipokine profiles of patients with RC differ from the healthy population, possibly reflecting an adaptation to the disease rather than a triggering factor. These differences may find clinical applications for the prognosis of disease evolution.

Increased incidence of colon cancer among individuals younger than 50 years: A 17 years analysis from the cancer registry of the municipality of Milan, Italy

BACKGROUND

Colorectal cancer (CRC) overall incidence has been decreasing in the last decade. However, there is evidence of an increasing frequency of early-onset CRC in young individuals in several countries. The aim of this study is to evaluate the trends of CRC occurrence over 17 years in the municipality of Milan, Italy, focusing on early-onset CRC.

POPULATION AND METHODS

This retrospective study was performed using the Cancer Registry of the municipality of Milan, including all cases of CRC diagnosed 1999-2015. Incidence rates were stratified by age and anatomic subsite, and trends over time were measured using the estimated annual percentage change. Age-period-cohort modelling was used to disentangle the different effects.

RESULTS

18,783 cases of CRC were included. CRC incidence rates among individuals aged 50-60 years declined annually by 3% both in colon and in rectal cancer. Conversely, in adults younger than 50 years, overall CRC occurrence increased annually by 0.7%, with a diverging trend for colon (+2.6%) and rectal (-5.3%) cancer. Among individuals aged 60 years and older, CRC incidence rates increased by 1.0% annually up to 2007, and decrease thereafter by 4% per year, both for colon and rectal cancer. Age-period-cohort models showed a reduction of CRC risk for the cohorts born up to 1979, followed by an increase in younger cohorts. In contrast, rectal cancer among women showed a systematic risk decrease for all birth cohorts.

CONCLUSIONS

The study highlights increasing incidence of colon cancer in younger subjects and a decrease in incidence rates for rectal cancer in females.

Mediation of associations between adiposity and colorectal cancer risk by inflammatory and metabolic biomarkers

Inflammation and hyperinsulinemia may drive associations between adiposity and colorectal cancer (CRC) risk, but few studies have examined this hypothesis using mediation analysis. We used inverse odds ratio weighting and logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) for estimated total effects (OR^TE ) of body mass index, waist circumference, and adult weight gain on CRC risk, and estimated effects operating through seven inflammatory and metabolic biomarkers (natural indirect effect; OR^NIE ) or through paths independent of these biomarkers (natural direct effect; OR^NDE ) among 209 CRC cases and 382 matched controls nested within the Health Professionals Follow-up Study, a prospective cohort of male health professionals. A one-interquartile range (IQR) increase in body mass index (3.6 kg/m² ) was associated with an OR^TE of 1.40 (95% CI: 1.13, 1.73), which decomposed into an OR^NIE of 1.26 (95% CI: 0.97, 1.52) and an OR^NDE of 1.11 (0.87, 1.42), with possibly stronger mediation by these biomarkers for adult weight gain (IQR = 10.4 kg; OR^TE = 1.32 [95% CI: 1.06, 1.64]; OR^NIE = 1.47 [95% CI: 1.01, 1.81]; OR^NDE = 0.89 [95% CI: 0.72, 1.11]), but no mediation for waist circumference. Mediation appeared to be stronger for the metabolic biomarkers than the inflammatory biomarkers. Inflammatory and metabolic mechanisms may mediate associations between both body mass index and adult weight gain with CRC risk.

Sirtuin 1 genetic variation, energy balance and colorectal cancer risk by sex and subsite in the Netherlands Cohort Study

Sirtuin 1 (SIRT1) is an energy-sensing protein, which may affect tumorigenesis. We used SIRT1 variants as time-independent indicators of SIRT1 involvement in carcinogenesis and we studied two tagging SIRT1 variants in relation to colorectal cancer (CRC) risk. We also evaluated known energy balance-related CRC risk factors within SIRT1 genotype strata. The Netherlands Cohort Study includes 120,852 individuals and has 20.3 years follow-up (case-cohort: n_subcohort = 5000; n_{CRC cases} = 4667). At baseline, participants self-reported weight, weight at age 20, height, trouser/skirt size reflecting waist circumference, physical activity, and early life energy restriction. SIRT1 rs12778366 and rs10997870 were genotyped in toenail DNA available for ~75% of the cohort. Sex- and subsite-specific Cox hazard ratios (HRs) showed that the rs12778366 CC versus TT genotype decreased CRC and colon cancer risks in women (HR_CRC = 0.53, 95% confidence interval: 0.30–0.94) but not men. Multiplicative interactions were observed between SIRT1 variants and energy balance-related factors in relation to CRC endpoints, but the direction of associations was not always conform expectation nor specific to one genotype stratum. In conclusion, these results support SIRT1 involvement in colon cancer development in women. No conclusions could be made regarding a modifying effect of SIRT1 variants on associations between energy balance-related factors and CRC risk.

Addressing the Perfect Storm: Biomarkers in Obesity and Pathophysiology of Cardiometabolic Risk

BACKGROUND

The worldwide rise of obesity has provoked intensified research to better understand its pathophysiology as a means for disease prevention. Several biomarkers that may reflect various pathophysiological pathways that link obesity and cardiometabolic diseases have been identified over the past decades.

CONTENT

We summarize research evidence regarding the role of established and novel obesity-related biomarkers, focusing on recent epidemiological evidence for detrimental associations with cardiometabolic diseases including obesity-related cancer. The reviewed biomarkers include biomarkers of glucose–insulin homeostasis (insulin, insulin-like growth factors, and C-peptide), adipose tissue biomarkers (adiponectin, omentin, apelin, leptin, resistin, and fatty-acid-binding protein-4), inflammatory biomarkers (C-reactive protein, interleukin 6, tumor necrosis factor α), and omics-based biomarkers (metabolites and microRNAs).

SUMMARY

Although the evidence for many classical obesity biomarkers, including adiponectin and C-reactive protein (CRP), in disease etiology has been initially promising, the evidence for a causal role in humans remains limited. Further, there has been little demonstrated ability to improve disease prediction beyond classical risk factors. In the era of “precision medicine,” there is an increasing interest in novel biomarkers, and the extended list of potentially promising biomarkers, such as adipokines, cytokines, metabolites, and microRNAs, implicated in obesity may bring new promise for improved, personalized prevention. To further evaluate the role of obesity-related biomarkers as etiological and early-disease-prediction targets, well-designed studies are needed to evaluate temporal associations, replicate findings, and test clinical utility of novel biomarkers. In particular, studies to determine the therapeutic implications of novel biomarkers beyond established metabolic risk factors are highly warranted.