A prospective study of waist circumference and body mass index in relation to colorectal cancer incidence

Abdominal obesity and digestive system cancer: a systematic review and meta-analysis of prospective studies

BACKGROUND

The diagnostic criteria for abdominal obesity are usually waist circumference or waist-to-hip ratio. The magnitude of the risks for cancers of the digestive system and abdominal obesity is unknown. To assess whether abdominal obesity increases the risk of digestive cancer, we conducted a systematic review and meta-analysis of prospective cohort studies in a database.

METHODS

PubMed, Embase, and Web of Science databases were searched from their inception to December 2022. The 9-star Newcastle Ottawa Scale was used to assess  study quality. Pooled relative risks and 95% confidence intervals were calculated using fixed or random effect models respectively. The stability of the results was explored by one-by-one exclusion. Subgroup analysis was conducted to explore sources of heterogeneity. Publication bias was evaluated by Begg's and Egger's tests.

RESULTS

A total of 43 cohort studies were included. There were 42 and 31 studies in the meta-analysis of waist circumference and waist-to-hip ratio on digestive system cancer, respectively. The results of the meta-analysis revealed that the greater waist circumference and waist-to-hip ratio were correlated with increased incidence of digestive system cancers: waist circumference: RR 1.48, 95% CI 1.38-1.59, p < 0.001; waist-to-hip ratio: RR 1.33, 95% CI 1.28-1.38, p = 0.001. Subgroup analysis by cancer type showed that higher WC and WHR would increase the prevalence of LC, PC, GC, EC, and CRC. The sensitivity analysis was conducted by a one-by-one elimination method, and the results of the meta-analysis remained stable. It is proved that the results were robust by the trim-and-fill method.

CONCLUSIONS

There was evidence to suggest that abdominal obesity increased the incidence of digestive cancer, it is necessary to take appropriate measures to reduce abdominal obesity. Waist circumference and waist-to-hip ratio may be better predictors of digestive system cancers. However, the association between waist circumference and digestive system cancer was greater, so more attention should be paid to measuring abdominal obesity with waist circumference.

Associations of Albumin and BMI with Colorectal Cancer Risk in the Southern Community Cohort Study: a Prospective Cohort Study

BACKGROUND

Obesity may increase colorectal cancer (CRC) risk through mechanisms of increased inflammation. Although BMI is the most used adiposity indicator, it may less accurately measure adiposity in Black populations. Herein, we investigate associations between BMI, low albumin as an inflammation biomarker, and CRC risk in a racially diverse cohort.

METHODS

Participant data arise from 71,141 participants of the Southern Community Cohort Study, including 724 incident CRC cases. Within the cohort, 69% are Black. Blood serum albumin concentrations, from samples taken at enrollment, were available for 235 cases and 567 controls. Controls matched by age, sex, and race were selected through incidence density sampling. Cox proportional hazards calculated BMI and CRC risk associations (hazard ratios [HRs]; 95% confidence intervals [CIs]. Conditional logistic regression calculated albumin and CRC risk associations (odds ratios [ORs]; 95%CIs).

RESULTS

Underweight, but not overweight or obese, compared to normal BMI was associated with increased CRC risk (HR:1.75, 95%CI:1.00-3.09). Each standard deviation increase of albumin was associated with decreased CRC risk, particularly for those who self-identified as non-Hispanic Black (OR: 0.56, 95%CI:0.34-0.91), or female (OR:0.54, 95%CI:0.30-0.98), but there was no evidence for interaction by these variables (p-interactions > 0.05). Moreover, albumin concentration was lower in Black than White participants. Mediation analysis suggested that the relation between albumin and CRC was not mediated by BMI.

CONCLUSIONS

Null associations of overweight/obesity with CRC risk demonstrates limited utility of BMI, especially among Black populations. Low albumin may indicate CRC risk. In Black individuals, albumin may better predict adiposity related risks than BMI.

Colon Cancer and Obesity: A Narrative Review

Obesity has played a crucial role in the pathogenesis of various cancers, including colorectal cancer (CRC). Obesity has shown to increase the blood levels of insulin, insulin-like growth factor-1 (IGF-1), leptin, resistin, inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1) which in turn acts via various signaling pathways to induce colonic cell proliferation and in turn CRC development. It has been shown that estrogen can prevent and cause CRC based on which receptor it acts. Obese patients have relatively low levels of ghrelin and adiponectin that inhibit cell proliferation which further adds to their risk of developing CRC. Obesity can alter the microbial flora of the gut in such a way as to favor carcinogenesis. Weight loss and good physical activity have been related to a reduced incidence of CRC; obese individuals should be screened for CRC and counseled about the importance of weight reduction, diet, and exercise. The best way of screening is using BMI and waist circumference (WC) to calculate the CRC risk in obese people. This study has reviewed the association between obesity and its pathophysiological association with CRC development.

Cancer mortality in a population-based cohort of American Indians - The strong heart study

BACKGROUND

Cancer mortality among American Indian (AI) people varies widely, but factors associated with cancer mortality are infrequently assessed.

METHODS

Cancer deaths were identified from death certificate data for 3516 participants of the Strong Heart Study, a population-based cohort study of AI adults ages 45-74 years in Arizona, Oklahoma, and North and South Dakota. Cancer mortality was calculated by age, sex and region. Cox proportional hazards model was used to assess independent associations between baseline factors in 1989 and cancer death by 2010.

RESULTS

After a median follow-up of 15.3 years, the cancer death rate per 1000 person-years was 6.33 (95 % CI 5.67-7.04). Cancer mortality was highest among men in North/South Dakota (8.18; 95 % CI 6.46-10.23) and lowest among women in Arizona (4.57; 95 % CI 2.87-6.92). Factors independently associated with increased cancer mortality included age, current or former smoking, waist circumference, albuminuria, urinary cadmium, and prior cancer history. Factors associated with decreased cancer mortality included Oklahoma compared to Dakota residence, higher body mass index and total cholesterol. Sex was not associated with cancer mortality. Lung cancer was the leading cause of cancer mortality overall (1.56/1000 person-years), but no lung cancer deaths occurred among Arizona participants. Mortality from unspecified cancer was relatively high (0.48/100 person-years; 95 % CI 0.32-0.71).

CONCLUSIONS

Regional variation in AI cancer mortality persisted despite adjustment for individual risk factors. Mortality from unspecified cancer was high. Better understanding of regional differences in cancer mortality, and better classification of cancer deaths, will help healthcare programs address cancer in AI communities.

Visceral Adiposity and Cancer: Role in Pathogenesis and Prognosis

The prevalence of being overweight and obese has been expanded dramatically in recent years worldwide. Obesity usually occurs when the energetic introit overtakes energy expenditure from metabolic and physical activity, leading to fat accumulation mainly in the visceral depots. Excessive fat accumulation represents a risk factor for many chronic diseases, including cancer. Adiposity, chronic low-grade inflammation, and hyperinsulinemia are essential factors of obesity that also play a crucial role in tumor onset. In recent years, several strategies have been pointed toward boundary fat accumulation, thus limiting the burden of cancer attributable to obesity. While remodeling fat via adipocytes browning seems a tempting prospect, lifestyle interventions still represent the main pathway to prevent cancer and enhance the efficacy of treatments. Specifically, the Mediterranean Diet stands out as one of the best dietary approaches to curtail visceral adiposity and, therefore, cancer risk. In this Review, the close relationship between obesity and cancer has been investigated, highlighting the biological mechanisms at the basis of this link. Finally, strategies to remodel fat, including browning and lifestyle interventions, have been taken into consideration as a major perspective to limit excess body weight and tumor onset.

Waist circumference, body mass index, and colorectal cancer risk according to diabetes status: A Korean nationwide population-based cohort study

BACKGROUND AND AIM

We investigated the relationship of BMI and waist circumference with the risk of colorectal cancer (CRC) using a population-based cohort database and to explore the relationship of CRC with diabetes status.

METHODS

Retrospective data (age >20 years) on anthropometric variables, blood parameters of fasting sugar, lipid levels, and blood pressure were collected from the National Health Insurance Corporation database between 2009 and 2012. Cox regression models were used to estimate hazard ratio (HR) and corresponding 95% confidence intervals (95% CI).

RESULTS

Of the 23 121 360 people studied, 120 579 were diagnosed with CRC after a median follow-up period of 5.4 years. Both waist circumference and body mass index were positively associated with increased risk of CRC, regardless of age or sex. After mutual adjustment, only waist circumference was significantly associated with increased risk of CRC (HR = 1.275, 95% CI: 1.205-1.349). When the risk of CRC was compared according to diabetes status among people with the same waist circumference range, risk of CRC was higher for those with worse diabetes status.

CONCLUSION

When waist circumference and body mass index were mutually adjusted, only waist circumference was associated with CRC risk. In addition, the risk of CRC is gradually higher in those with worsening diabetes, even if their waist circumferences are within the same range.

Obesity Has a Stronger Relationship with Colorectal Cancer in Postmenopausal Women than Premenopausal Women

BACKGROUND

To examine the relationship between obesity measured by waist circumference (WC) and body mass index (BMI) and the incidence of colorectal cancer in premenopausal and postmenopausal women.

METHODS

A total of 1,418,180 premenopausal and 4,854,187 postmenopausal women without cancer at baseline and ages over 40 were identified using the Korean National Health Insurance System Cohort during 2009 to 2014. The hazard ratio (HR) for colorectal cancer incidence was assessed according to menopausal state using Cox proportional hazards models.

RESULTS

During a mean follow-up period of 7.2 years, 7,094 and 57,449 colorectal cancer cases occurred in premenopausal and postmenopausal women, respectively. Compared with the reference group (WC 65-75), the HRs [95% confidence interval (CI)] of colorectal cancer in WC <65, 75-85, 85-95, and >95 groups were 1.01 (0.91-1.11), 1.02 (0.97-1.07), 1.09 (1.00-1.18), and 1.31 (1.12-1.52), respectively, in premenopausal women and 1.01 (0.95-1.17), 1.09 (1.07-1.12), 1.19 (1.00-1.18), and 1.30 (1.25-1.35), respectively, in postmenopausal women. Compared with the reference group (BMI 18.5-22.9), HRs (95% CI) for colorectal cancer in BMI <18.5, 23-25, 25-30, and >30 groups were 0.99 (0.87-1.14), 0.99 (0.94-1.06), 0.98 (0.92-1.04), and 1.06 (0.92-1.20), respectively, in premenopausal women. In postmenopausal women, those values were 0.99 (0.93-1.05), 1.05 (1.03-1.08), 1.11 (1.09-1.13), and 1.20 (1.16-1.25), respectively.

CONCLUSIONS

WC is associated with the risk of colorectal cancer in both groups of women, but this association was stronger in postmenopausal women than in premenopausal women. BMI increased the incidence of colorectal cancer only in postmenopausal women IMPACT: Obesity has a stronger relationship with colorectal cancer in postmenopausal women than in premenopausal women.

Long-term status of predicted body fat percentage, body mass index and other anthropometric factors with risk of colorectal carcinoma: Two large prospective cohort studies in the US

Anthropometric measurements, such as body mass index (BMI), waist circumference, and body fat percentage, have been used as indicators of obesity. Despite evidence that excess body fat is a risk factor for colorectal carcinoma (CRC), the magnitude of the association of BMI and other obesity indicators with the long-term risk of CRC remains unclear. Utilizing a Cox proportional hazards regression model, we examined differential associations between predicted body fat percentage and BMI with the risk of CRC (n = 2,017). The associations between CRC incidence and different adiposity measurements were also assessed. Predicted body fat percentage had a similar increased risk of CRC risk as BMI. In multivariable-adjusted analyses, the hazard ratio for CRC in the second to fifth quintiles (compared to the first quintile) of predicted body fat percentage were 1.32, 1.31, 1.53 and 2.09 for men (ptrend  < 0.001) and 0.91, 0.90, 0.98 and 1.15 for women (ptrend = 0.03). Among various anthropometric measurements, predicted fat mass and waist circumference were slightly more strongly associated with CRC risk than BMI. In conclusion, the novel anthropometric prediction equations provided further evidence that a greater amount of body fat might contribute to CRC risk in both sexes. An innovative approach enabled us to estimate the susceptibilities of specific body composition with CRC risk, in an inexpensive and minimally invasive manner. Furthermore, the typically used measures of BMI and waist circumference are robust measures of adiposity to predict cancer risk in a relatively healthy population.

Colorectal cancer risk factors in asymptomatic Chilean population: a survey of international collaboration between Japan and Chile

In Chile, the mortality from colorectal cancer has been on the rise. A national screening program based on a fecal immunochemical test was started in 2012 as an international collaboration with Japan. This case-control study was designed to identify the risk factors for colorectal cancer, with a goal of increasing the participation rate for colorectal cancer screening. In accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines, we conducted a case-control study from 2012 to 2017; 23 845 asymptomatic participants were enrolled in the study. Participants who were fecal immunochemical test-positive or had a family history of colorectal cancer underwent a colonoscopy. We analyzed the odds ratio of the risk factors for colorectal cancer, including sex, age, family history, BMI, hypertension, diabetes, regular use of nonsteroidal anti-inflammatory drugs, alcohol consumption, smoking, physical activity, and daily intake of certain food items. For the screening program, 202 cases of colorectal cancer were detected, and 195 of them were evaluated pathologically after resection. Of these, 173 cases (88.7%) had colorectal cancer stage 0/1, 151 (77.4%) of which were treated with endoscopic resection. In the multivariate analysis, male sex, family history of colorectal cancer, and low intake of cereals or fibers were closely related to a high colorectal cancer incidence. Moreover, participants in their 60s and 70s had a higher incidence of colorectal cancer than those in their 50s. These results suggest that intensive screening of the high-risk population can help in improving the detection of colorectal cancer, whereas higher consumption of cereals or fibers can be effective in preventing its onset.

Obesity, genomic ancestry, and socioeconomic variables in Latin American mestizos

OBJECTIVES

This article aims to assess the contribution of genomic ancestry and socioeconomic status to obesity in a sample of admixed Latin Americans.

METHODS

The study comprised 6776 adult volunteers from Brazil, Chile, Colombia, Mexico, and Peru. Each volunteer completed a questionnaire about socioeconomic variables. Anthropometric variables such as weight, height, waist, and hip circumference were measured to calculate body indices: body mass index, waist-to-hip ratio and waist-to-height ratio (WHtR). Genetic data were extracted from blood samples, and ancestry was estimated using chip genotypes. Multiple linear regression was used to evaluate the relationship between the indices and ancestry, educational level, and economic well-being. The body indices were dichotomized to obesity indices by using appropriate thresholds. Odds ratios were calculated for each obesity index.

RESULTS

The sample showed high percentages of obesity by all measurements. However, indices did not overlap consistently when classifying obesity. WHtR resulted in the highest prevalence of obesity. Overall, women with low education level and men with high economic wellness were more likely to be obese. American ancestry was statistically associated with obesity indices, although to a lesser extent than socioeconomic variables.

CONCLUSIONS

The proportion of obesity was heavily dependent on the index and the population. Genomic ancestry has a significant influence on the anthropometric measurements, especially on central adiposity. As a whole, we detected a large interpopulation variation that suggests that better approaches to overweight and obesity phenotypes are needed in order to obtain more precise reference values.

Cancer risk in relation to body fat distribution, evaluated by DXA-scans, in postmenopausal women - the Prospective Epidemiological Risk Factor (PERF) study

Studies with direct measures of body fat distribution are required to explore the association between central and general obesity to cancer risk in postmenopausal women. This study investigates the association between central obesity and general obesity to overall/site-specific cancer risk in postmenopausal women. The analysis included 4,679 Danish postmenopausal women. Body fat distribution was evaluated by whole-body dual-energy X-ray absorptiometry scanners. Cancer diagnoses were extracted from the Danish Cancer Registry and multivariable Cox regression models explored the association between cancer risk and central obesity after adjusting for BMI. Our results showed that high central obese women had a 50% increased risk of overall cancer relative to low central obese women (Q1vs.Q4: [HR:1.50, CI:1.20-1.88]). For site-specific cancers, central obesity was significantly associated with Respiratory (Q1vs.Q4: [HR:2.01, CI:1.17-3.47]), Gastrointestinal (Q1vs.Q4: [HR:1.55, CI:0.99-2.41]) and Female genital organs (Q1vs.Q4: [HR:1.95, CI:1.00-3.78]) cancer diagnoses. Sub-analyses stratified by smoking-habits found a significant association between central obesity and a cancer diagnosis for current (Q1vs.Q4: [HR:1.93, CI:1.25-2.99]) and former smokers (Q1vs.Q4: [HR:1.90, CI:1.23-2.94]). These analyses suggest that central obesity is associated with some cancers in postmenopausal women independent of BMI.

Diagnostic value of chemerin in lower gastrointestinal diseases-a review

Chemerin is a protein secreted among others by adipose tissue and liver, with a dual pro- and anti-inflammatory role in the body. These molecules exert systemic effects by modulating tissue-specific immune response and metabolism. Chemerin isoforms correlate with the turnover of fatty acids and lipoproteins that could affect intestinal inflammation. Although chemerin may interact with three types of receptors, CMKLR1 is the best studied. In this paper we reviewed current knowledge about the relationship between chemerin and lower gastrointestinal (GI) diseases, such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and colorectal cancer (CRC). A more detailed understanding of the role of the adipose tissue in the GI tract will not only unravel the pathophysiology of chronic intestinal diseases, but may also indicate a new therapeutic tool for their management.

A case-control study of the association between metabolic syndrome and colorectal cancer: a comparison of International Diabetes Federation, National Cholesterol Education Program Adults Treatment Panel III, and World Health Organization definitions

Background

Metabolic syndrome was linked with various chronic diseases, including cancer. The study on the effect of metabolic syndrome on colorectal cancer (CRC) was not conducted in Malaysia. Therefore, this study aims to determine the association between metabolic syndromes and its components with CRC, based on the three established definitions.

Methods

A multi-centred matched case control study was conducted in five local hospitals. A total of 140 histologically confirmed CRC cases were matched with 280 cancer free controls. Mean value and prevalence of the components of metabolic syndrome between cases and controls were measured based on the three definitions. A multiple variable analysis using Cox regression was conducted to measure the strength of the association between the definitions of MetS, components of MetS and risk of CRC.

Results

Multiple variable analyses showed that metabolic syndrome significantly and independently increased the risk of CRC, with an odds ratio ranging from 1.79 to 2.61. This study identified that the definition of metabolic syndrome by the International Diabetes Federation is the most sensitive in predicting the risk of CRC, compared to metabolic syndrome as defined by the World Health Organization and National Cholesterol Education Program Adults Treatment Panel III. Abdominal obesity, low HDL-cholesterol, and hypertension were identified as the three core risk factors, which promote inflammatory signals that contribute to metabolic syndrome and an increased risk of CRC.

Conclusions

These data hypothesized that simple measurement of abdominal obesity, abnormal BP and HDL-cholesterol especially using International Diabetes Federation (IDF) definition of MetS for South Asians for to detect individuals at CRC risk may have higher clinical utility than applying other universal complex MetS definitions.

Height and body fatness and colorectal cancer risk: an update of the WCRF-AICR systematic review of published prospective studies

PURPOSE

There is no published dose-response meta-analysis on the association between height and colorectal cancer risk (CRC) by sex and anatomical sub-site. We conducted a meta-analysis of prospective studies on the association between height and CRC risk with subgroup analysis and updated evidence on the association between body fatness and CRC risk.

METHODS

PubMed and several other databases were searched up to November 2016. A random effects model was used to calculate dose-response summary relative risks (RR's).

RESULTS

47 studies were included in the meta-analyses including 50,936 cases among 7,393,510 participants. The findings support the existing evidence regarding a positive association of height, general and abdominal body fatness and CRC risk. The summary RR were 1.04 [95% (CI)1.02-1.05, I² = 91%] per 5 cm increase in height, 1.02 [95% (CI)1.01-1.02, I² = 0%] per 5 kg increase in weight, 1.06 [95% (CI)1.04-1.07, I² = 83%] per 5 kg/m2 increase in BMI, 1.02 [95% (CI)1.02-1.03, I² = 4%] per 10 cm increase in waist circumference, 1.03 [95% (CI)1.01-1.05, I² = 16%] per 0.1 unit increase in waist to hip ratio. The significant association for height and CRC risk was similar in men and women. The significant association for BMI and CRC risk was stronger in men than in women.

CONCLUSION

The positive association between height and risk of CRC suggests that life factors during childhood and early adulthood might play a role in CRC aetiology. Higher general and abdominal body fatness during adulthood are risk factors of CRC and these associations are stronger in men than in women.

Relationship between Lipid Phenotypes, Overweight, Lipid Lowering Drug Response and KIF6 and HMG-CoA Genotypes in a Subset of the Brisighella Heart Study Population

The existence of genetic traits might explain the susceptibility to develop hypercholesterolemia and the inter-individual differences in statin response. This study was performed to evaluate whether individuals' polymorphisms in HMG-CoA and KIF6 genes are independently associated with hypercholesterolemia, other lipid-associated traits, and statin response in unselected individuals enrolled in the Brisighella heart study (Survey 2012). A total of 1622 individuals, of which 183 under statin medication, were genotyped for a total of five polymorphisms (KIF6 rs20455, rs9471077, rs9462535; HMG-CoA rs3761740, rs3846662). The relationships between the five loci and clinical characteristics were analyzed. The principal basic parameters calculated on 12 h fasting blood included total cholesterol (TC), High Density Lipoprotein Cholesterol (HDL-C), Low-Density Lipoprotein Cholesterol (LDL-C), and triglycerides (TG). Hypercholesterolemia was defined as a TC >200 mg/dL or use of lipid-lowering medication. 965 individuals were characterized by hypercholesterolemia; these subjects were significantly older (p < 0.001), with body mass index (BMI) and waist circumference significantly higher (p < 0.001) compared to the others. HMG-CoA rs3846662 GG genotype was significantly over-represented in the hypercholesterolemic group (p = 0.030). HMG-CoA rs3846662 genotype was associated with the level of TC and LDL-C. Furthermore, in the same subset of untreated subjects, we observed a significant correlation between the KIF6 rs20455 and HDL-C. KIF6 variants were associated with a significantly lower (rs20455) or higher (rs9471077 and rs9462535) risk of obesity, in males only. No association between responsiveness to statins and the polymorphisms under investigation were observed. Our results showed associations between HMG-CoA rs3846662 and KIF6 rs20455 and lipid phenotypes, which may have an influence on dyslipidemia-related events. Moreover, this represents the first study implicating KIF6 variants with obesity in men, and point to the possible involvement of this genetic locus in the known gender-related differences in coronary artery disease.

Abdominal obesity and colorectal cancer risk: systematic review and meta-analysis of prospective studies

The association between abdominal obesity (as measured by waist circumference (WC) and waist-to-hip ratio (WHR)) and colorectal cancer (CRC) has not been fully quantified, and the magnitude of CRC risk associated with abdominal obesity is still unclear. A meta-analysis of prospective studies was performed to elucidate the CRC risk associated with abdominal obesity. Pubmed and Embase were searched for studies assessing the association between abdominal obesity and CRC risk. Relative risks (RRs) with 95% confidence intervals (95% CIs) were pooled using random-effects model of meta-analysis. Nineteen prospective cohort studies from eighteen publications were included in this meta-analysis. A total of 12,837 CRC cases were identified among 1,343,560 participants. Greater WC and WHR were significantly associated with increased risk of total colorectal cancer (WC: RR 1.42, 95% CI 1.30, 1.55; WHR: RR 1.39, 95% CI 1.25, 1.53), colon cancer (WC: RR 1.53, 95% CI 1.36, 1.72; WHR: 1.39, 95% CI 1.18, 1.63), and rectal cancer (WC: RR 1.20, 95% CI 1.03, 1.39; WHR: RR 1.22, 95% CI 1.05, 1.42). Subgroup analyses further identified the robustness of the association above. No obvious risk of publication bias was observed. In summary, abdominal obesity may play an important role in the development of CRC.

Increases in waist circumference independent of weight in Mongolia over the last decade: the Mongolian STEPS surveys

Background

In Mongolia, mean waist circumference (WC) has increased dramatically over the last decade, however, it is unknown whether these increases have been greater than corresponding increases in weight. In this study we aimed to assess whether recent increases in WC were greater than expected from changes in weight in Mongolian adults.

Methods

We used data on 13260 Mongolian adults, aged between 18 and 64 years, who participated in one of three (2005, 2009, 2013) nationally representative cross-sectional surveys. Linear regression was used to estimate changes in mean WC over time, adjusted for age, sex, height and weight. We also estimated the age-standardised prevalence for four obesity classification categories (not obese; obese by WC only; obese by body mass index (BMI) only; obese by both BMI and WC) at each survey year.

Results

The estimated mean WC in 2009 and 2013, respectively, was 1.26 cm (95% CI: 0.35 to 2.17) and 1.88 cm (95% CI: 1.09 to 2.67) greater compared to 2005, after adjusting for age, sex, height and weight. Between 2005 and 2013, the age-standardised prevalence of those obese according to both BMI and WC increased from 8.0 to 13.6% for men and from 16.5 to 25.5% for women. During the same period, the percentage who were obese by WC only increased from 1.8 to 4.8% for men and from 16.5 to 26.8% for women. In contrast, the percentage who were obese by BMI only remained relatively stable (women: 2.4% in 2005 to 1.0% in 2013; men: 2.7% in 2005 to 4.0% in 2013).

Conclusion

Over the last decade, among Mongolian adults, there has been substantially greater increase in WC and the prevalence of abdominal obesity than would be expected from increases in weight. Women are at greater risk than men of being misclassified as not obese if obesity is defined using BMI only. Obesity should be monitored using WC in addition to BMI to ensure the prevalence of obesity is not underestimated.

Quantitative Assessment of Visceral Obesity and Postoperative Colon Cancer Outcomes

BACKGROUND

Quantitative computed tomography (CT) assessment of visceral adiposity may be superior to body mass index (BMI) as a predictor of surgical morbidity. We sought to examine the association of CT measures of obesity and BMI with short-term postoperative outcomes in colon cancer patients.

METHODS

In this retrospective study, 110 patients treated with colectomy for stage I-III colon cancer were classified as obese or non-obese by preoperative CT-based measures of adiposity or BMI [obese: BMI ≥ 30 kg/m², visceral fat area (VFA) to subcutaneous fat area ratio (V/S) ≥0.4, and VFA > 100 cm²]. Postoperative morbidity and mortality rates were compared.

RESULTS

Obese patients, by V/S and VFA but not BMI, were more likely to be male and have preexisting hypertension and diabetes. The overall complication rate was 25.5%, and there were no mortalities. Obese patients by VFA (with a trend for V/S but not BMI) were more likely to develop postoperative complications as compared to patients classified as non-obese: VFA (30.5 vs.10.7%, p = 0.03), V/S (29.2 vs. 9.5%, p = 0.05), and BMI (32.4 vs. 21.9%, p = 0.23).

CONCLUSIONS

Elevated visceral obesity quantified by CT is associated with the presence of key metabolic comorbidities and increased postoperative morbidity and may be superior to BMI for risk stratification.

Mendelian randomization study of adiposity-related traits and risk of breast, ovarian, prostate, lung and colorectal cancer

BACKGROUND

Adiposity traits have been associated with risk of many cancers in observational studies, but whether these associations are causal is unclear. Mendelian randomization (MR) uses genetic predictors of risk factors as instrumental variables to eliminate reverse causation and reduce confounding bias. We performed MR analyses to assess the possible causal relationship of birthweight, childhood and adult body mass index (BMI), and waist-hip ratio (WHR) on the risks of breast, ovarian, prostate, colorectal and lung cancers.

METHODS

We tested the association between genetic risk scores and each trait using summary statistics from published genome-wide association studies (GWAS) and from 51 537 cancer cases and 61 600 controls in the Genetic Associations and Mechanisms in Oncology (GAME-ON) Consortium.

RESULTS

We found an inverse association between the genetic score for childhood BMI and risk of breast cancer [odds ratio (OR) = 0.71 per standard deviation (s.d.) increase in childhood BMI; 95% confidence interval (CI): 0.60, 0.80; P = 6.5 × 10(-5)). We also found the genetic score for adult BMI to be inversely associated with breast cancer risk (OR = 0.66 per s.d. increase in BMI; 95% CI: 0.57, 0.77; P = 2.5 × 10(-7)), and positively associated with ovarian cancer (OR = 1.35; 95% CI: 1.05, 1.72; P = 0.017), lung cancer (OR = 1.27; 95% CI: 1.09, 1.49; P = 2.9 × 10(-3)) and colorectal cancer (OR = 1.39; 95% CI: 1.06, 1.82, P = 0.016). The inverse association between genetically predicted adult BMI and breast cancer risk remained even after adjusting for directional pleiotropy via MR-Egger regression.

CONCLUSIONS

Findings from this study provide additional understandings of the complex relationship between adiposity and cancer risks. Our results for breast and lung cancer are particularly interesting, given previous reports of effect heterogeneity by menopausal status and smoking status.

Body weight, fat distribution and colorectal cancer risk: a report from cohort studies of 134255 Chinese men and women

OBJECTIVE

To evaluate the association of body size and fat distribution with risk of colorectal cancer (CRC) in Chinese men and women.

DESIGN

Population-based, prospective cohort study.

SUBJECTS

The analysis included 134 255 Chinese adults enrolled in the Shanghai Women’s Health Study and the Shanghai Men’s Health Study, with an average follow-up of 11.0 and 5.5 years, respectively.

MEASUREMENTS

Waist circumference (WC), body mass index (BMI) and waist-to-hip ratio (WHR) were measured by trained interviewers at baseline. Multivariable Cox models were used to calculate adjusted hazard ratios (HRs) for incident CRC.

RESULTS

A total of 935 incident CRC cases were identified. Both measures of general adiposity (measured by BMI) and central adiposity (measured by WHR and WC) were significantly associated with increased risk of colon cancer in men but not in women. Multivariable adjusted HRs for colon cancer in men in the highest compared with the lowest quintiles were 2.15 (95% CI: 1.35-3.43; P for trend = 0.0006) for BMI, 1.97 (95% CI: 1.19-3.24; P for trend = 0.0004) for WHR and 2.00 (95% CI: 1.21-3.29; P for trend = 0.0002) for WC. The BMI-associated risk was attenuated in analyses stratified by WHR, while the WHR-associated risk remained significant in the high BMI stratum (HR for comparison of extreme tertiles of WHR: 3.38, 95% CI: 1.47-7.75; P for trend =0.0002). None of these anthropometric measures were significantly associated with rectal cancer.

CONCLUSION

Obesity, particularly central obesity, was associated with increased risk of colon cancer in men.

Distribution and Impact of the Visceral Fat Area in Patients With Colorectal Cancer

Purpose

The purposes of this study were to investigate the distribution of the visceral fat area (VFA) and general obesity and to compare visceral and general obesity as predictors of surgical outcomes of a colorectal cancer resection.

Methods

The prospectively collected data of 102 patients with preoperatively-diagnosed sigmoid colon or rectal cancer who had undergone a curative resection at Pusan National University Yangsan Hospital between April 2011 and September 2012 were reviewed retrospectively. Men with a VFA of >130 cm² and women with a VFA of >90 cm² were classified as obese (VFA-O, n = 22), and the remaining patients were classified as nonobese (VFA-NO, n = 80).

Results

No differences in morbidity, mortality, postoperative bowel recovery, and readmission rate after surgery were observed between the 2 groups. However, a significantly higher number of harvested lymph nodes was observed in the VFA-NO group compared with the VFA-O group (19.0 ± 1.0 vs. 13.5 ± 1.2, respectively, P = 0.001).

Conclusion

Visceral obesity has no influence on intraoperative difficulties, postoperative complications, and postoperative recovery in patients with sigmoid colon or rectal cancer.

Adipose tissue, obesity and adipokines: role in cancer promotion

Adipose tissue is a complex organ with endocrine, metabolic and immune regulatory roles. Adipose depots have been characterized to release several adipocytokines that work locally in an autocrine and paracrine fashion or peripherally in an endocrine fashion. Adipocyte hypertrophy and excessive adipose tissue accumulation, as occurs during obesity, dysregulates the microenvironment within adipose depots and systemically alters peripheral tissue metabolism. The term "adiposopathy" is used to describe this promotion of pathogenic adipocytes and associated adipose - elated disorders. Numerous epidemiological studies confirm an association between obesity and various cancer forms. Proposed mechanisms that link obesity/adiposity to high cancer risk and mortality include, but are not limited to, obesity-related insulin resistance, hyperinsulinemia, sustained hyperglycemia, glucose intolerance, oxidative stress, inflammation and/or adipocktokine production. Several epidemiological studies have demonstrated a relationship between specific circulating adipocytokines and cancer risk. The aim of this review is to define the function, in normal weight and obesity states, of well-characterized and novel adipokines including leptin, adiponectin, apelin, visfatin, resistin, chemerin, omentin, nesfatin and vaspin and summarize the data that relates their dysfunction, whether associated or direct effects, to specific cancer outcomes. Overall research suggests most adipokines promote cancer cell progression via enhancement of cell proliferation and migration, inflammation and anti-apoptosis pathways, which subsequently can prompt cancer metastasis. Further research and longitudinal studies are needed to define the specific independent and additive roles of adipokines in cancer progression and reoccurrence.

Long-term status and change of body fat distribution, and risk of colorectal cancer: a prospective cohort study

BACKGROUND

Although obesity has been linked to an increased risk of colorectal cancer (CRC), the risk associated with long-term status or change of body fat distribution has not been fully elucidated.

METHODS

Using repeated anthropometric assessments in the Nurses' Health Study and Health Professionals Follow-up Study, we prospectively investigated cumulative average waist circumference, hip circumference and waist-to-hip ratio, as well as their 10-year changes over adulthood, in relation to CRC risk over 23-24 years of follow-up. Cox proportional hazards models were used to calculate the hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

High waist circumference, hip circumference and waist-to-hip ratio were all associated with a higher CRC risk in men, even after adjusting for body mass index. The association was attenuated to null in women after adjusting for body mass index. Ten-year gain of waist circumference was positively associated with CRC risk in men (P for trend = 0.03), but not in women (P for trend = 0.34).Compared with men maintaining their waist circumference, those gaining waist circumference by ≥ 10 cm were at a higher risk of CRC, with a multivariable-adjusted HR of 1.59 (95% CI, 1.01-2.49). This association appeared to be independent of weight change.

CONCLUSIONS

Abdominal adiposity, independent of overall obesity, is associated with an increased CRC risk in men but not in women. Our findings also provide the first prospective evidence that waist circumference gain during adulthood may be associated with higher CRC risk in men, thus highlighting the importance of maintaining a healthy waist for CRC prevention.

Derivation and Validation of a Scoring System to Stratify Risk for Advanced Colorectal Neoplasia in Asymptomatic Adults: A Cross-sectional Study

BACKGROUND

Several methods are recommended equally strongly for colorectal cancer screening in average-risk persons. Risk stratification would enable tailoring of screening within this group, with less invasive tests (sigmoidoscopy or occult blood tests) for lower-risk persons and colonoscopy for higher-risk persons.

OBJECTIVE

To create a risk index for advanced neoplasia (colorectal cancer and adenomas or serrated polyps ≥1.0 cm, villous histology, or high-grade dysplasia) anywhere in the colorectum, using the most common risk factors for colorectal neoplasia.

DESIGN

Cross-sectional study.

SETTING

Multiple endoscopy units, primarily in the Midwest.

PATIENTS

Persons aged 50 to 80 years undergoing initial screening colonoscopy (December 2004 to September 2011).

MEASUREMENTS

Derivation and validation of a risk index based on points from regression coefficients for age, sex, waist circumference, cigarette smoking, and family history of colorectal cancer.

RESULTS

Among 2993 persons in the derivation set, prevalence of advanced neoplasia was 9.4%. Risks for advanced neoplasia in persons at very low, low, intermediate, and high risk were 1.92% (95% CI, 0.63% to 4.43%), 4.88% (CI, 3.79% to 6.18%), 9.93% (CI, 8.09% to 12.0%), and 24.9% (CI, 21.1% to 29.1%), respectively (P < 0.001). Sigmoidoscopy to the descending colon in the low-risk groups would have detected 51 of 70 (73% [CI, 61% to 83%]) advanced neoplasms. Among 1467 persons in the validation set, corresponding risks for advanced neoplasia were 1.65% (CI, 0.20% to 5.84%), 3.31% (CI, 2.08% to 4.97%), 10.9% (CI, 8.26% to 14.1%), and 22.3% (CI, 16.9% to 28.5%), respectively (P < 0.001). Sigmoidoscopy would have detected 21 of 24 (87.5% [CI, 68% to 97%]) advanced neoplasms.

LIMITATIONS

Split-sample validation; results apply to first-time screening.

CONCLUSION

This index stratifies risk for advanced neoplasia among average-risk persons by identifying lower-risk groups for which noncolonoscopy strategies may be effective and efficient and a higher-risk group for which colonoscopy may be preferred.

PRIMARY FUNDING SOURCE

National Cancer Institute, Walther Cancer Institute, Indiana University Simon Cancer Center, and Indiana Clinical and Translational Sciences Institute.

Television watching and risk of colorectal adenoma

Background:

Prolonged TV watching, a major sedentary behaviour, is associated with increased risk of obesity and diabetes and may involve in colorectal carcinogenesis.

Methods:

We conducted a cross-sectional analysis among 31 065 men with ⩾1 endoscopy in the Health Professionals Follow-up Study (1988–2008) to evaluate sitting while watching TV and its joint influence with leisure-time physical activity on risk of colorectal adenoma. Logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs).

Results:

Prolonged sitting while watching TV was significantly associated with increased risk of colorectal adenoma (n=4280), and adjusting for physical activity or a potential mediator body mass index did not change the estimates. The ORs (95% CIs) across categories of TV watching (0–6, 7–13, 14–20, and 21+ h per week) were 1.00 (referent), 1.09 (1.01–1.17), 1.16 (1.06–1.27), and 1.10 (0.97–1.25) (OR per 14-h per week increment=1.11; 95% CI: 1.04–1.18; P_trend=0.001). Compared with the least sedentary (0–6 h per week of TV) and most physically active (highest quintile) men, the most sedentary (14+ h per week) and least active (lowest quintile) men had a significant increased risk of adenoma (OR=1.25; 95% CI: 1.05–1.49), particularly for high-risk adenoma.

Conclusions:

Prolonged TV viewing is associated with modest increased risk of colorectal adenoma independent of leisure-time physical activity and minimally mediated by obesity.

The risk of colonic adenomas and colonic cancer in obesity

Increasing body fatness has been associated with an increased burden from colorectal cancer. An increased susceptibility spanning the entire continuum from precancerous adenomatous polyps to the development of colorectal cancer, poor outcome with treatment, and reduced survival when compared to those with normal body weight has been described. It is unknown which age period and which degree and duration of excess weight are associated with increased colorectal cancer risk. It is uncertain whether weight loss can reverse this risk. If it can, how long will the new lower or normal weight be maintained to effect enduring risk reduction? Furthermore, it is controversial whether the increased burden of colorectal cancer warrants earlier and/or more frequent screening for obese persons. This article reviews the relationship between obesity and colorectal neoplasia, explores the postulated mechanism of carcinogenesis, discusses interventions to reduce the burden of disease, and suggests future directions of research.

Association of obesity and overweight with overall survival in colorectal cancer patients: a meta-analysis of 29 studies

PURPOSE

Previous studies that assessed the relationship between obesity, overweight, and survival in colorectal cancer (CRC) have provided conflicting results. Therefore, we quantitatively summarized existing evidence to estimate the association between obesity/overweight and overall survival (OS) in CRC patients and explored potentially important sources of variability.

METHODS

Eligible studies were identified via PubMed and EMBASE searches. The summary hazard ratio (sHR) was estimated using a fixed-effects or random-effects model according to the heterogeneity between the studies. Meta-regression and subgroup analyses were performed to explore potential sources of heterogeneity.

RESULTS

A total of 29 eligible studies, with 51,303 CRC patients, were finally included. The overall analysis showed worse OS among obese patients [sHR 1.10, 95 % confidence intervals (CI) 1.06-1.15], but not among overweight patients (sHR 0.92, 95 % CI 0.86-1.00), than in normal-weight patients. Considerable heterogeneity was observed across studies, which was primarily attributed to the timing of body mass index (BMI) assessment (meta-regression p < 0.05). The association between obesity and worse OS was strengthened when BMI was assessed before diagnosis (sHR 1.30, 95 % CI, 1.17-1.44). Conversely, post-diagnostic, in particular post-treatment, overweight was associated with a better OS (sHR 0.79, 95 % CI 0.70-0.91). Other factors, including gender, geographic location, and stage, may also modify the prognostic value of obesity or overweight.

CONCLUSIONS

Obese but not overweight patients appear to have worse OS than normal-weight patients with CRC. The associations of obesity and overweight with OS in CRC patients majorly depend upon the timing of BMI assessment.

Effect of 8-week nutrition counseling to increase phytochemical rich fruit and vegetable consumption in korean breast cancer patients: a randomized controlled trial

High fruit and vegetable consumption is associated with a lower risk of breast cancer. The incidence of breast cancer is continuously increasing in Korea, but only a few studies on nutrition intervention in breast cancer patients has been reported. The aim of this study was to investigate whether an 8-week nutrition intervention based on dietary counseling can promote fruit and vegetable consumption, increase serum antioxidant nutrient levels, and improve quality of life in Korean breast cancer patients. Sixty-one breast cancer patients received either standard care (n = 31) or nutrition counseling (n = 30). The standard care group was given brochures recommending phytochemical rich diet. The intervention group was provided with two nutrition counseling sessions and one cooking class session, thereby encouraged subjects to eat at least 10 or more servings of fruits and vegetables per day. After 8-week intervention, waist circumference in the intervention group was significantly decreased (p < 0.001) even though no difference was reported for body mass index. Energy intake (p = 0.007), fiber (p < 0.001), and antioxidant nutrient (vitamin A, C, E, and β-carotene, p < 0.001, respectively) intakes were significantly increased. Serum antioxidant level was also increased significantly, i.e., vitamin A (p = 0.048); vitamin E (p = 0.004). Total vegetable intake (excluding kimchi intake) in the intervention group was increased from 425 g to 761 g (p < 0.001), fruit consumption was also increased from 232 g to 334 g (p < 0.001), while standard care group did not show any significant change. Our study showed that nutrition counseling and providing cooking tips helped to encourage the patient to consume and maintain more fruit and vegetable intakes.

The role of obesity in gastrointestinal cancer: evidence and opinion

There is increasing recognition of the impact of being overweight and obese on the development of cancers at diverse sites including the gastrointestinal tract. Large epidemiological studies indicate that up to 14% of tumours may be related to obesity. Pathophysiological mechanisms underpinning this association are not well understood and so are discussed in this review.

Comparison of associations of body mass index, abdominal adiposity, and risk of colorectal cancer in a large prospective cohort study

BACKGROUND

Increased body mass index (BMI) is an established colorectal cancer risk factor. High waist circumference or waist-hip-ratio (WHR) may better reflect an abnormal metabolic state and be more predictive of colorectal cancer risk than BMI.

METHODS

We examined BMI, waist circumference, WHR, and hip circumference in relation to colorectal cancer risk among 203,177 participants followed for 10 years. We derived standardized colorectal cancer risk estimates for each anthropometric parameter and compared predictive characteristics (Harrell's C-index). In women, we examined whether hormone replacement therapy (HRT) use modified the associations between anthropometric measures and colorectal cancer.

RESULTS

We ascertained 2,869 colorectal cancers. In men, increased colon cancer risks were associated with BMI [HR per SD, 1.14; 95% confidence interval (CI), 1.08-1.20], waist circumference (HR per SD, 1.17; 95% CI, 1.08-1.27), and WHR (HR per SD, 1.09; 95% CI, 1.04-1.14). In women, anthropometric variables were unrelated to colon cancer. For men and women, anthropometric variables were unrelated to rectal cancer. Compared with BMI, waist circumference and WHR did not materially influence colon cancer prediction models [C-index changes: -0.0041 and 0.0046 (men); 0.0004 and 0.0005 (women)]. In current HRT users, colon cancer was inversely or suggestively inversely associated with waist circumference (HR per SD, 0.78; 95% CI, 0.63-0.97) and WHR (HR per SD, 0.88; 95% CI, 0.76-1.01), but positively related to hip circumference (HR per SD, 1.39; 95% CI, 1.13-1.71).

CONCLUSION

BMI, waist circumference, and WHR show comparable positive associations with colon cancer in men. Associations between anthropometric measures and colon cancer are weak or null in women, but there is some evidence for effect modification by HRT.

IMPACT

These findings may improve our understanding of the relation of adiposity to colorectal cancer.

Meta-analyses of colorectal cancer risk factors

PURPOSE

Demographic, behavioral, and environmental factors have been associated with increased risk of colorectal cancer (CRC). We reviewed the published evidence and explored associations between risk factors and CRC incidence.

METHODS

We identified 12 established non-screening CRC risk factors and performed a comprehensive review and meta-analyses to quantify each factor's impact on CRC risk. We used random-effects models of the logarithms of risks across studies: inverse-variance weighted averages for dichotomous factors and generalized least squares for dose-response for multi-level factors.

RESULTS

Significant risk factors include inflammatory bowel disease (RR = 2.93, 95 % CI 1.79-4.81); CRC history in first-degree relative (RR = 1.80, 95 % CI 1.61-2.02); body mass index (BMI) to overall population (RR = 1.10 per 8 kg/m(2) increase, 95 % CI 1.08-1.12); physical activity (RR = 0.88, 95 % CI 0.86-0.91 for 2 standard deviations increased physical activity score); cigarette smoking (RR = 1.06, 95 % CI 1.03-1.08 for 5 pack-years); and consumption of red meat (RR = 1.13, 95 % CI 1.09-1.16 for 5 servings/week), fruit (RR = 0.85, 95 % CI 0.75-0.96 for 3 servings/day), and vegetables (RR = 0.86, 95 % CI 0.78-0.94 for 5 servings/day).

CONCLUSIONS

We developed a comprehensive risk modeling strategy that incorporates multiple effects to predict an individual's risk of developing CRC. Inflammatory bowel disease and history of CRC in first-degree relatives are associated with much higher risk of CRC. Increased BMI, red meat intake, cigarette smoking, low physical activity, low vegetable consumption, and low fruit consumption were associated with moderately increased risk of CRC.

Obesity and risk of colorectal cancer: a systematic review of prospective studies

Background

Mounting evidence indicates that obesity may be associated with the risk of colorectal cancer (CRC). To conduct a systematic review of prospective studies assessing the association of obesity with the risk of CRC using meta-analysis.

Methodology/Principal Findings

Relevant studies were identified by a search of MEDLINE and EMBASE databases before January 2012, with no restrictions. We also reviewed reference lists from retrieved articles. We included prospective studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) for the association between general obesity [measured using body mass index (BMI)] or central obesity [measured using waist circumference (WC)] and the risk of colorectal, colon, or rectal cancer. Approximately 9, 000, 000 participants from several countries were included in this analysis. 41 studies on general obesity and 13 studies on central obesity were included in the meta-analysis. The pooled RRs of CRC for the obese vs. normal category of BMI were 1.334 (95% CI, 1.253–1.420), and the highest vs. lowest category of WC were 1.455 (95% CI, 1.327–1.596). There was heterogeneity among studies of BMI (P<0.001) but not among studies of WC (P = 0.323).

Conclusions

Both of general and central obesity were positively associated with the risk of CRC in this meta-analysis.

The mTOR Pathway and the Role of Energy Balance Throughout Life in Colorectal Cancer Etiology and Prognosis: Unravelling Mechanisms Through a Multidimensional Molecular Epidemiologic Approach

Timing of exposure to lifestyle factors that influence energy balance may differentially affect colorectal cancer (CRC) risk and prognosis. Caloric restriction in youth and short stature, as markers of early-life exposures, have shown to decrease CRC risk, whereas large body size and low physical activity levels in adulthood are established risk factors for CRC. Regarding prognosis, overweight, sarcopenia, and their co-occurrence (sarcopenic obesity) may negatively influence the health and quality of life of CRC survivors. There is mechanistic support for disruption of the mammalian target of rapamycin (mTOR) pathway as an underlying mechanism possibly driving these associations, because mTOR integrates signals from growth factors, nutrients, mutagens, and hormones to induce cell proliferation, resistance to apoptosis, and autophagy. However, epidemiologic evidence connecting mTOR to energy-balance-related CRC throughout the lifespan is scarce. This perspective proposes how multidimensional molecular epidemiologic studies can shed light on the etiology and prognosis of energy-balance-related CRC.

A longitudinal study of the metabolic syndrome and risk of colorectal cancer in postmenopausal women

The metabolic syndrome is associated with increased risk of diabetes and coronary heart disease. Although higher BMI and other related factors have been frequently associated with colorectal cancer, whether the metabolic syndrome is associated with the risk of colorectal cancer is unclear. We therefore assessed the association of the metabolic syndrome with the risk of colorectal cancer in a subsample of participants of the Women's Health Initiative who had repeated measurements of the components of the syndrome at baseline and during follow-up. Women with diabetes at baseline enrollment were excluded. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) at baseline and in time-dependent analyses. Among 4862 eligible women, 81 incident cases of colorectal cancer were identified over a median follow-up of 12 years. Presence of the metabolic syndrome at baseline was associated with increased risk of colorectal cancer (HR 2.15, 95% CI 1.30-3.53) and colon cancer (HR 2.28, 95% CI 1.31-3.98). These associations were largely explained by positive associations of serum glucose and systolic blood pressure with both outcomes. Time-dependent covariate analyses supported the baseline findings. Our results suggest that the positive association of the metabolic syndrome with risk of colorectal cancer is largely accounted for by serum glucose levels and systolic blood pressure. The biological mechanism underlying these associations remains to be clarified.

Racial differences in measures of obesity and risk of colon adenoma

Obesity is an established risk factor for several malignancies. However, the specific measurement of obesity most relevant to colon neoplasia is still debated, and evidence has suggested gender and racial differences in this measurement. In this study, we sought to compare which measurement--BMI, waist circumference (WC), waist-to-hip ratio (WHR) or waist-to-height ratio (WHtR)--is most strongly associated with development of colon adenomas, a precursor of colon cancer, and to investigate differences in this association between racial groups. We confirmed the strong association between WHR, as a measure of central obesity, and development of colon neoplasia. In our overall analysis, patients in the highest WHR quartile showed a substantial increase in risk of colon adenomas compared to patients in the lowest WHR quartile (odds ratio (OR) = 1.82, 95% confidence interval (CI): 1.12-2.71, P(trend) = 0.0017). In stratified analyses, we noted that strongly associated obesity measures in European Americans were WC (OR = 2.38, 95% CI = 1.45-3.92, P(trend) = 0.0004) and BMI (OR = 2.18, 95% CI = 1.37-3.49, P(trend) = 0.0015), whereas in African Americans, WHR was the strongest and the only obesity measure statistically significantly associated with adenoma risk (OR = 2.12, 95% CI = 1.05-4.30, P(trend) = 0.025). Our data highlight the importance of obesity in the development of early colon neoplasia and suggest substantial racial differences in the measures of obesity most strongly associated with risk of colon adenomas.

The relationship between nonalcoholic fatty liver disease and colorectal cancer: the future challenges and outcomes of the metabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is closely related to insulin resistance, metabolic syndrome, obesity, type 2 diabetes, and dyslipidaemia. Obesity and metabolic syndrome are associated with an increased cancer risk, and recent evidence demonstrated an association between NAFLD and colorectal cancer (CRC). The mechanism of how NAFLD can be associated with increased risk of CRC is not fully understood; however, NAFLD represents a condition of profound insulin resistance and a proinflammatory state. Insulin and insulin-like growth factors may promote the development of CRC through their proliferative and antiapoptotic effects. Patients with NAFLD have reduced expression of adiponectin, an adipokine with anti-inflammatory effects. Importantly, hypoadiponectinemia is associated with an increased risk of CRC. Decreased levels of adiponectin lead to increased insulin levels due to marked insulin resistance and in turn increased insulin growth factor-1 (IGF-1). Insulin binds to IGF-1 receptors and plays an important role in cell proliferation, apoptosis, and increased production of vascular endothelial growth factor, an angiogenic factor that supports cancer growth. Further studies are needed to establish (i) the pathophysiology of NAFLD with colorectal cancer, (ii) the benefit of early screening of CRC in NAFLD patients, and (iii) the impact of treatment of NAFLD in the modulation of the risk of colorectal cancer.

Body mass index and mortality from all causes and major causes in Japanese: results of a pooled analysis of 7 large-scale cohort studies

BACKGROUND

We pooled data from 7 ongoing cohorts in Japan involving 353 422 adults (162 092 men and 191 330 women) to quantify the effect of body mass index (BMI) on total and cause-specific (cancer, heart disease, and cerebrovascular disease) mortality and identify optimal BMI ranges for middle-aged and elderly Japanese.

METHODS

During a mean follow-up of 12.5 years, 41 260 deaths occurred. The Cox proportional hazards model was used to estimate hazard ratios (HRs) for each BMI category, after controlling for age, area of residence, smoking, drinking, history of hypertension, diabetes, and physical activity in each study. A random-effects model was used to obtain summary measures.

RESULTS

A reverse-J pattern was seen for all-cause and cancer mortality (elevated risk only for high BMI in women) and a U- or J-shaped association was seen for heart disease and cerebrovascular disease mortality. For total mortality, as compared with a BMI of 23 to 25, the HR was 1.78 for 14 to 19, 1.27 for 19 to 21, 1.11 for 21 to 23, and 1.36 for 30 to 40 in men, and 1.61 for 14 to 19, 1.17 for 19 to 21, 1.08 for 27 to 30, and 1.37 for 30 to 40 in women. High BMI (≥27) accounted for 0.9% and 1.5% of total mortality in men and women, respectively.

CONCLUSIONS

The lowest risk of total mortality and mortality from major causes of disease was observed for a BMI of 21 to 27 kg/m(2) in middle-aged and elderly Japanese.

Visceral obesity is associated with outcomes of total mesorectal excision for rectal adenocarcinoma

BACKGROUND AND OBJECTIVES

General obesity, measured by the body mass index (BMI), increases the technical difficulty of total mesorectal excision (TME) but does not affect oncologic outcomes. The purpose of this study is to compare visceral and general obesity as predictors of outcomes of TME for rectal adenocarcinoma.

METHODS

Adult patients undergoing TME for rectal adenocarcinoma were retrospectively identified. Preoperative computed tomography scans were used to measure abdominal circumference (AC), visceral (VFA), and subcutaneous fat area (SFA). BMI, AC, VFA, SFA, total fat area (TFA, sum of VFA and SFA), and VFA/SFA ratio were examined for association with operative, postoperative, oncologic, and survival outcomes in a univariate analysis model.

RESULTS

Between 1999 and 2009, 113 patients met inclusion criteria. Increasing VFA and VFA/SFA ratio were associated with reduced lymph node retrieval (P = 0.03 and P = 0.009, respectively). The association between increasing VFA/SFA ratio with delayed resumption of oral intake (P = 0.05) and prolonged overall survival (P = 0.003) were also significant. Increasing BMI was associated with improved overall (P = 0.02) but not disease-free survival (P = 0.14).

CONCLUSION

Visceral obesity, measured by VFA/SFA ratio, is a better predictor of postoperative, oncologic, and survival outcomes after TME for rectal adenocarcinoma than general obesity measured by the BMI.

Visceral adiposity, insulin resistance and cancer risk

BACKGROUND

There is a well established link between obesity and cancer. Emerging research is characterising this relationship further and delineating the specific role of excess visceral adiposity, as opposed to simple obesity, in promoting tumorigenesis. This review summarises the evidence from an epidemiological and pathophysiological perspective.

METHODS

Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles identified. Selection of articles was based on peer review, journal and relevance.

RESULTS

Numerous epidemiological studies consistently identify increased risk of developing carcinoma in the obese. Adipose tissue, particularly viscerally located fat, is metabolically active and exerts systemic endocrine effects. Putative pathophysiological mechanisms linking obesity and carcinogenesis include the paracrine effects of adipose tissue and systemic alterations associated with obesity. Systemic changes in the obese state include chronic inflammation and alterations in adipokines and sex steroids. Insulin and the insulin-like growth factor axis influence tumorigenesis and also have a complex relationship with adiposity. There is evidence to suggest that insulin and the IGF axis play an important role in mediating obesity associated malignancy.

CONCLUSIONS

There is much evidence to support a role for obesity in cancer progression, however further research is warranted to determine the specific effect of excess visceral adipose tissue on tumorigenesis. Investigation of the potential mechanisms underpinning the association, including the role of insulin and the IGF axis, will improve understanding of the obesity and cancer link and may uncover targets for intervention.

Self-reported and measured anthropometric data and risk of colorectal cancer in the EPIC-Norfolk study

BACKGROUND

Epidemiological studies have shown inconsistent results for the association between body size and colorectal cancer (CRC) risk. Inconsistencies may be because of the reliance on self-reported measures of body size.

OBJECTIVE

We examined the association of self-reported and directly assessed anthropometric data (body height, weight, body mass index (BMI), waist, hip, waist-to-hip ratio (WHR) and chest circumference) with CRC risk in the EPIC-Norfolk study.

DESIGN

A total of 20,608 participants with complete self-reported and measured height and weight and without any history of cancer were followed up an average of 11 years, during which 357 incident CRC cases were recorded. Hazard Ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.

RESULTS

After adjustment for confounders, HRs among women in the highest quintile of the body size measure relative to the lowest quintile showed that measured height (HR=1.98, 95% CI=1.19-3.28, P (trend)=0.009), measured waist circumference (HR=1.65, 95% CI=0.97-2.86, P (trend)=0.009) and measured WHR (HR=2.07, 95% CI=1.17-3.67, P (trend)=0.001) were associated with increased CRC risk. Associations using corresponding self-reported measures were attenuated and not statistically significant. Conversely, the association of BMI with CRC risk in women was weaker using measured BMI (HR=1.57, 95% CI=0.91-2.73, P (trend)=0.05) compared with self-reported BMI (HR=1.97, 95% CI=1.18-3.30, P (trend)=0.02). In men no significantly increased CRC risk was observed with any of the anthropometric measures.

CONCLUSIONS

Measured height, waist circumference and WHR were associated with CRC risk in women, whereas any significant associations with those measures were attenuated when self-reported data were used.

Functional variants of -1318T > G and -673C > T in c-Jun promoter region associated with increased colorectal cancer risk by elevating promoter activity

C-Jun plays important roles in the development of multiple cancers, but no well-designed association studies have been conducted to assess the roles of its genetic polymorphisms in cancer risk. In a cohort of 1016 pairs of colorectal cancer (CRC) patients and matched cancer-free controls, we investigated two genetic polymorphisms in the promoter regions of the c-Jun (rs4646999, -673C > T and rs2760501, -1318T > G) via the Taqman assay and evaluated the association between two polymorphisms and risk of CRC. We found that both the -1318G and -673C variant genotypes were associated with an increased risk of CRC [-1318TG: odds ratio (OR) = 1.26, 95% confidence interval (CI) = 1.04-1.54; -1318GG: OR = 1.63, 95% CI = 1.03-2.60; -673CT: OR = 1.60, 95% CI = 1.23-2.07; -673CC: OR = 1.80, 95% CI = 1.36-2.37]. Haplotype association analysis showed that compared with the carriers of -1318T-673T haplotype, carriers of the -1318T-673C, -1318G-673T, and -1318G-673C haplotypes all had a significantly increased risk of CRC (P < 0.05 for all). The combined genotypes incorporating both polymorphisms obtained a more significantly additive risk of CRC (one variant genotype: OR = 1.81, 95% CI = 1.30-2.51; two variant genotype: OR = 2.42, 95% CI = 1.70-3.44). Moreover, we found that the change of the -1318T to G allele interact with the -673T to C allele elevated the transcription activity of the c-Jun, and we confirmed the same trends by analyzing c-Jun protein expression in the CRC tissues from patients carrying different number of variant genotypes. This study suggests that -673C > T and -1318T > G genetic variants in c-Jun promoter regions contribute to an increased risk of CRC, possibly by elevating the transcription activity and protein expression levels that appeared to upregulate activity of c-Jun thus tumorigenesis.

Metabolic factors and the risk of colorectal cancer in 580,000 men and women in the metabolic syndrome and cancer project (Me-Can)

BACKGROUND

The metabolic syndrome (MetS) has been related to an increased risk of colorectal cancer, but the modest size of previous studies precluded detailed characterization of the role of individual MetS factors and their interaction on risk.

METHODS

In the Metabolic Syndrome and Cancer Project (Me-Can), data on body mass index (BMI), blood pressure, and blood levels of glucose, cholesterol, and triglycerides were available for 578,700 men and women. The mean age of participants at baseline was 44 years, and the mean follow-up was 12 years. Relative risks (RR) of colorectal cancer per 1 standard deviation increment in Z score of factors and for a combined MetS score, were calculated from Cox regression models, including adjustment for potential confounders.

RESULTS

During follow-up, 2834 men and 1861 women were diagnosed with colorectal cancer. The RR of colorectal cancer for the MetS score was 1.25 (95% confidence interval [CI], 1.18-1.32) in men, and 1.14 (95% CI, 1.06-1.22) in women. Significant associations also were observed in men for BMI (RR, 1.07; 95% CI, 1.02-1.13), blood pressure (RR, 1.10; 95% CI, 1.02-1.18), and triglycerides (RR, 1.17; 95% CI, 1.06-1.28) and, in women, for BMI (RR, 1.08; 95% CI, 1.01-1.15). There was no significant positive interaction between the metabolic factors on risk.

CONCLUSIONS

The combination of metabolic factors and some separate factors was related to an increased risk of colorectal cancer, but there was no interaction between metabolic factors.

Waist circumference predicts increased complications in rectal cancer surgery

BACKGROUND

The impact of obesity on development of postoperative complications after gastrointestinal surgery remains controversial. This may be due to the fact that obesity has been calculated by body mass index, a measure that does not account for fat distribution. We hypothesized that waist circumference, a measure of central obesity, would better predict complications after high-risk gastrointestinal procedures.

METHODS

Retrospective review of an institutional cancer database identified consecutive cases of men undergoing elective rectal resections. Waist circumference was calculated from preoperative imaging.

RESULTS

From 2002 to 2009, 152 patients with mean age 65.2 ± 0.75 years and body mass index 28.0 ± 0.43 kg/m(2) underwent elective resection of rectal adenoma or carcinoma. Increasing body mass index was not significantly associated with risk of postoperative complications including infection, dehiscence, and reoperation. Greater waist circumference independently predicted increased risk of superficial infections (OR 1.98, 95% CI 1.19-3.30, p < 0.008) and a significantly greater risk of having one or more postoperative complications (OR 1.56, 95% CI 1.04-2.34, p < 0.034).

CONCLUSIONS

Waist circumference, a measure of central obesity, is a better predictor of short-term complications than body mass index and can be used to identify patients who may benefit from more aggressive infection control and prevention.