Does high body fatness increase the risk of presence and growth of colorectal adenomas followed up in situ for 3 years?

Impact of an Abdominal Compression Bandage on the Completion of Colonoscopy for Obese Adults: A Prospective Randomized Controlled Trial

METHODS

Eligible patients were randomly allocated into the abdominal bandage and conventional groups during a routine colonoscopy. The primary outcome was CCR.

RESULTS

A total of 250 eligible patients were randomly assigned to the abdominal bandage and conventional groups from January 2021 to April 2021. Eleven patients (five in the abdominal bandage group and six in the conventional group) were excluded due to schedule cancellation after randomization, and 239 patients were eventually included in the final analysis. There were no significant differences between the two groups regarding baseline characteristics (P > 0.05). Furthermore, no significant differences were observed in terms of advanced adenoma detection rate (AADR), polyp detection rate (PDR), bowel preparation scale (BBPS), bubble scale (BS), and withdrawal time between the two groups (P > 0.05). However, compared with the conventional group, the cecal insertion time (CIT) of the abdominal bandage group was significantly shortened (279.00 (234.50-305.75) vs. 421.00 (327.00-485.00), P < 0.001), and the CCR (96.7% vs. 88.2%, P = 0.01) and adenoma detection rate (ADR) (47.5% vs. 32.8%, P < 0.001) were improved. Besides, logistic regression analysis showed that body mass index (BMI) and abdominal compression bandage were associated with CCR.

CONCLUSIONS

Abdominal compression bandages could effectively shorten CIT and improve CCR and ADR for obese patients during a routine colonoscopy. This trial is registered with the Chinese Clinical Trial Registry (No. ChiCTR2100043556).

Efficacy and tolerability of colonoscopies in overweight and obese patients: Results from a national database on gastrointestinal endoscopic outcomes

Background and study aims  Gastroenterologists are encountering a rising number of obese patients requiring colonoscopy. Existing literature regarding colonoscopy outcomes in this population is scant and conflicting. We analyzed a nationwide cohort of patients to identify the effects of body mass index (BMI) on colonoscopy success, efficacy, and tolerability. Patients and methods  The Clinical Outcomes Research Initiative (CORI) endoscopic database was queried for all colonoscopies in adults between 2008-2014. Patients were stratified into four cohorts based on BMI classification for comparison. Multivariable analysis was performed to identify the effect of BMI on procedure outcome, efficacy and tolerability. Results  Of 41,401 procedures, 27,696 met study inclusion criteria. Of these, 49.4 % were performed for colorectal cancer screening, most commonly under anesthesia directed sedation. Patient discomfort was the reason for an incomplete colonoscopy in 18.7 % of all cases, and more frequent among the overweight and obese cohorts. An inadequate bowel preparation was most common in the class III obesity cohort. Compared to the normal BMI group, a BMI ≥ 30 and < 40 kg/m ² was associated with an increased odds of an incomplete colonoscopy ( P  = 0.001for overweight, P  = 0.0004 for class I/II obesity), longer procedure ( P  < 0.05 for all) and poorer tolerance ( P  < 0.0001 for class I/II obesity, P  = 0.016 for class III obesity). Anesthesia-administered sedation was more commonly used than endoscopist directed sedation amongst the obese cohort compared with the normal BMI cohort ( P  < 0.0001). Conclusions  Endoscopists should consider the increased odds of incomplete colonoscopy, longer procedures, and poorer tolerance when performing colonoscopy in obese patients to improve clinical management and procedural outcome.

Association of body fat distribution and metabolic syndrome with the occurrence of colorectal adenoma: A case-control study

OBJECTIVE

Visceral fat is thought to play different roles in the carcinogenesis of the colon with peripheral fat. Our aim was to evaluate the association of body fat distribution measured by bioelectrical impedance analysis (BIA) with the incidence of colorectal adenoma (CRA).

METHODS

A total of 410 asymptomatic participants who underwent a screening colonoscopy from July 2017 to December 2019 in our center were recruited, including 230 with adenomas and 180 without detected adenomas. The participants' body fat was measured by BIA, including their body fat mass (BFM), body fat percentage (BFP), and waist-to-hip ratio. Parameters of metabolic syndrome (MetS), including waist circumference, blood pressure, fasting blood glucose (FBG), blood level of triglyceride, cholesterol, and high-density lipoprotein were measured as well.

RESULTS

According to univariate analysis, age, male sex, body mass index, waist circumference, BFM, waist-to-hip ratio, blood pressure, and FBG were higher in the adenoma group than in the adenoma-free group (P < 0.05). On multivariate logistical analysis (adjusted for age, sex, smoking, drinking, and family history of CRC), a high waist-to-hip ratio was associated with a high incidence of CRA (odds ratio [OR] 1.84, 95% confidence interval [CI] 1.09-3.09, P = 0.02). Only a large waist circumference in components of MetS was independently associated with the incidence of CRA (OR 1.90, 95% CI 1.17-3.08, P = 0.01) in the multivariate analysis.

CONCLUSION

Body fat distribution is associated with CRA, central obesity is a core risk factor for CRA in MetS. Chinese Clinical Trial Registration number: ChiCTR-RRC-17010862.

The Effect of Obesity on the Quality of Bowel Preparation for Colonoscopy: Results From a Large Observational Study

BACKGROUND

Obesity has been linked to suboptimal bowel preparation but this association has not been conclusively investigated in prospective studies.

GOALS

Our objective was to determine whether any relationship exists between obesity as measured by body mass index (BMI) and quality of bowel preparation.

STUDY

Adult patients who presented for outpatient colonoscopy at a single urban ambulatory surgery center within a 6-month period and fulfilled inclusion criteria were prospectively enrolled for the study. Patients were divided by BMI into subcategories based on the World Health Organization international classification of obesity. The Modified Aronchick scale was used to assess bowel preparation for colonoscopy. A univariate and multivariate analysis was used to determine a possible association between BMI and poor preparation.

RESULTS

A total of 1429 patients were evaluated. On the basis of inclusion criteria, 1314 subjects were analyzed, out of which 73% were overweight or obese. Inadequate bowel preparation was noted in 21.1% of patients. There was no correlation between obesity and the quality of the bowel preparation. Male gender (P=0.002), diabetes mellitus (P<0.0001), liver cirrhosis (P=0.001), coronary artery disease (P=0.003), refractory constipation (P<0.0001), and current smoking (P=0.01) were found to be independently predictive of poor bowel preparation.

CONCLUSIONS

Increased BMI is not predictive of suboptimal bowel preparation for colonoscopy. The results of our study are pivotal given the increased risk of colorectal cancer in obese patients and their known lower rate of colorectal cancer screening in certain populations. It is important to avoid subjecting these patients to an intensive bowel preparation that may further discourage screening in a patient population that requires it.

Obesity-related parameters and colorectal adenoma development

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Higher body mass index is associated with an increased risk of multiplicity in surveillance colonoscopy within 5 years

We aimed to evaluate whether obesity was associated with a certain clinicopathologic characteristics of metachronous CRA. This retrospective longitudinal cohort study included 2,904 subjects who had at least one resected CRA at index colonoscopy and who subsequently underwent one or more surveillance colonoscopies within 5 years. Of the 2,904 subjects, 60.9% (n = 1,769) were normal, 35.8% (n = 1,040) were overweight, and 3.3% (n = 95) were obese. Patients with any metachronous CRA were 53.7% (n = 1,559). In multivariate analyses, higher BMI at index colonoscopy was significantly associated with any metachronous CRA (overweight, OR = 1.07; obese, OR = 1.82; p for trend = 0.049). Regarding the multiplicity, the ORs of ≥ 3, ≥ 4 and ≥ 5 metachronous CRAs significantly increased as index BMI increased (p for trend < 0.001, = 0.007 and = 0.004, respectively). In negative binomial regression regarding the incidence for total number of metachronous CRA, the higher BMI the subject has at the time of index colonoscopy, the more metachronous CRAs the subject will have at the surveillance colonoscopy (p for trend = 0.016). Higher index BMI was significantly associated with the risk of multiple metachronous CRAs on surveillance colonoscopy within 5 years.

Weight Change and Obesity Are Associated with a Risk of Adenoma Recurrence

BACKGROUND

Obesity is reportedly a risk factor for colorectal adenoma. However, the influence of weight change and obesity on colorectal adenoma recurrence is unclear.

AIM

To investigate whether weight change and obesity are associated with recurrence and development of colorectal adenoma.

PATIENTS AND METHODS

Of 62,171 asymptomatic subjects who underwent a colonoscopy for a heath checkup between 2010 and 2011, this longitudinal study was performed with the 5297 subjects who underwent another colonoscopy between 2012 and 2013. The risk of recurrence or development of adenoma according to quartiles of weight change (<-1.6, -1.6 to 0.1, 0.2-1.8, and ≥1.9 kg) and baseline BMI categories (<25, 25-29, and ≥30 kg/m(2)) was assessed using Cox proportional hazards modeling.

RESULTS

The average period between visits 1 and 2 was 2.2 ± 0.6 years. Among the 2176 subjects with adenomas, the risk of recurrence of any adenoma increased with increasing weight change quartiles (p for trend = 0.030), whereas the risk of recurrence of advanced adenoma was not associated with weight change (p for trend = 0.852). The risk of recurrence of advanced adenoma increased with increasing baseline BMI categories (p for trend = 0.029). Among 3121 subjects with no adenoma, the risk of developing any adenoma increased with increasing baseline BMI categories (p for trend <0.001). However, the risk of developing any or advanced adenoma was not associated with weight change.

CONCLUSIONS

Weight change over 2.2 years affected adenoma recurrence and obesity was related to advanced adenoma recurrence and adenoma development.

[Comparison of blood leptin concentration and colonic mucosa leptin expression in colon adenoma patients and healthy control]

BACKGROUND/AIMS

Obesity increases the risk of colorectal cancer and adenomatous polyp, and one of the underlying mechanisms of this increase is considered to be due to the growth promoting effects of adipokines, such as leptin. In order to investigate this finding, leptin expression in the colonic tissue and blood leptin concentration of the colonic adenoma patients were compared to those of the control group.

METHODS

Colonic adenoma tissues were obtained by polypectomy (n=60). In these patients, normal colonic mucosa at remote areas from the polyp was also obtained and blood samples were collected as well. Age and sex matched control subjects were selected among those who showed normal colonic mucosa in health screening colonoscopy (n=60).

RESULTS

There was no significant difference in serum leptin concentration between the colonic adenoma patients and control subjects. Leptin expression was noted in 43.3% of the colonic adenomas, but only in 6.7% of normal colonic mucosa from the control subjects (p<0.01). There were ten cases of concurrent adenocarcinoma in situ in adenoma patients, eight cases of which expressed leptin (p=0.01). In adenoma group, leptin expression rate was significantly high in larger adenomas and in obese patients (p<0.05). However, there was no statistically significant relationship between leptin expression in colonic mucosa and serum leptin level.

CONCLUSIONS

Leptin expression was more frequently observed in colonic adenomas, especially in larger adenomas associated with adenocarcinoma in situ, but blood leptin level was not related to tissue leptin expression. Leptin expression was more frequently observed in obese patients from the adenoma group. Therefore, leptin may play an important role in colonic tumorigenesis and progression, especially in obese patient.

Increased risk of colorectal polyps in patients with non-alcoholic fatty liver disease undergoing liver transplant evaluation

BACKGROUND

Screening colonoscopy is a standard part of the liver transplant (LT) evaluation process. We aimed to evaluate the yield of screening colonoscopy and determine whether non-alcoholic fatty liver disease (NAFLD) was associated with an increased risk of colorectal neoplasia.

METHODS

We retrospectively assessed all patients who completed LT evaluation at our center between 1/2008-12/2012. Patients <50 years old and those without records of screening colonoscopy, or with greater than average colon cancer risk were excluded.

RESULTS

A total of 1,102 patients were evaluated, 591 met inclusion criteria and were analyzed. The mean age was 60 years, 67% were male, 12% had NAFLD and 88% had other forms of chronic liver disease. Overall, 42% of patients had a polyp found on colonoscopy: 23% with adenomas, 14% with hyperplastic polyps and with 1% inflammatory polyps. In the final multivariable model controlling for age, NAFLD [odds ratio (OR) 2.41, P=0.001] and a history of significant alcohol use (OR 1.69, P=0.004) were predictive of finding a polyp on colonoscopy. In addition, NAFLD (OR 1.95, P=0.02), significant alcohol use (OR 1.70, P=0.01) and CTP class C (OR 0.57, P=0.02) were associated with adenoma, controlling for age.

CONCLUSIONS

Screening colonoscopy in patients awaiting LT yields a high rate of polyp (43%) and adenoma (22%) detection, perhaps preventing the accelerated progression to carcinoma that can occur in immunosuppressed post-LT patients. Patients with NAFLD may be at a ~2 fold higher risk of adenomas and should be carefully evaluated prior to LT.

Sessile serrated adenomas versus conventional adenomas. Different polyps in different populations?

PURPOSE

The aim of this study was to determine risk factors for the development of sessile serrated adenomas (SSA/Ps) as well as to study differences between groups with SSA/Ps and conventional adenomas (tubular, tubulovillus and villus) in the general population.

METHODS

One hundred patients with normal colonoscopies, 27 patients with 53 SSA/Ps and 69 patients with 156 conventional adenomas were studied, epidemiological data were collected and calculations of body mass index and waist-to-hip ratio were performed prior to endoscopy. A univariate and a multivariate logistic regression analysis were performed using Stata 9.0.

RESULTS

SSA/Ps had a positive association with increasing age (p = 0.01), heavy smoking (≥20 packet years) (p = 0.001) and past history of polyps (p = 0.004) in comparison to normal population. SSA/Ps showed an inverse association with conventional adenomas for diabetes mellitus (p < 0.001) and arterial hypertension (p = 0.001). Meanwhile, female sex was positively associated with SSA/P development in comparison to conventional adenomas (p = 0.031).

CONCLUSIONS

Heavy smoking as a significant risk factor for developing SSA/Ps was confirmed from this study. It also seemed that patients with diabetes mellitus and/or hypertension developed conventional adenomas more frequently than SSA/Ps; on the contrary, females were at higher risk of developing SSA/Ps than conventional adenomas.

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.

Prevalence and risk factors of asymptomatic colorectal polyps in taiwan

Purpose. To investigate the prevalence and risk factors of hyperplastic and adenomatous colorectal polyps in a Taiwanese general population. Methods. From January 2009 to December 2011, consecutive asymptomatic subjects undergoing a routine health check-up were evaluated by colonoscopy. The colorectal polyps were assessed, and medical history and demographic data were obtained from each patient. Logistic regression analysis was conducted to search the independent risk factors for asymptomatic hyperplastic and adenomatous colorectal polyps. Results. Of the 1899 asymptomatic subjects, the prevalences of hyperplastic polyps and adenomatous polyps were 11.1% and 16.1%, respectively. Multivariate analysis revealed that high body mass index (BMI > 25: OR, 1.32, 95% CI, 1.05–1.71) and current smoking (OR, 1.87, 95% CI, 1.42–2.71) were independent predictors for hyperplastic colorectal polyps. Age over 60 years old (OR, 3.49, 95% CI, 1.86–6.51), high body mass index (BMI > 25: OR, 1.75, 95% CI, 1.21–2.71), heavy alcohol consumption (OR, 2.01, 95% CI, 1.02–3.99), and current smoking (OR, 1.31, 95% CI, 1.04–1.58) were independent predictors for adenomatous colorectal polyps. Conclusion. High BMI and smoking are common risk factors for both adenomatous and hyperplastic polyps. Old age and alcohol consumption are additional risk factors for the development of adenomatous polyps.

Impact of body mass index on the risk of colorectal adenoma in a metabolically healthy population

Metabolically healthy obese (MHO) states exist that seem to be protected from cardiovascular risks. Although obesity is a risk factor for colorectal adenoma (CRA), there has yet to be any study of the risks of CRA in MHO individuals. In this study, we compared CRA prevalence in MHO individuals versus metabolically healthy individuals who were normal in weight. This cross-sectional study involved 18,085 Korean adults (39.1 ± 6.7 years) who had a health checkup including a colonoscopy. High-risk CRA was defined as any adenoma over 1 cm, 3 or more adenomas, adenoma with a villous component, or high-grade dysplasia. Multinomial logistic regression models were used to measure the associations between body mass index (BMI) and the risk of low-risk and high-risk CRA. Low-risk and high-risk CRA were present in 9.3% and 1.4% of the study population, respectively. After adjusting for age, sex, smoking, drinking, exercise, family history of colorectal cancer, education, and use of analgesic and aspirin, compared with normal healthy individuals, the prevalence of low-risk and high-risk CRA was increased in MHO individuals [OR = 1.44; 95% confidence interval (CI), 1.23-1.69 and OR = 1.62; 95% CI, 1.09-2.41, respectively]. In fully adjusted models, the prevalence of low-risk and high-risk CRA was associated with increasing categories of BMI in a dose-response manner (P for trend < 0.001 and 0.01, respectively). Thus, excess body weight, even in the absence of a metabolic unhealthy state, was found to be positively associated with increased presence of CRAs.

Differences in epidemiologic risk factors for colorectal adenomas and serrated polyps by lesion severity and anatomical site

Using a case-control design, we evaluated differences in risk factors for colorectal polyps according to histological type, anatomical site, and severity. Participants were enrollees in the Group Health Cooperative aged 20-79 years who underwent colonoscopy in Seattle, Washington, between 1998 and 2007 and comprised 628 adenoma cases, 594 serrated polyp cases, 247 cases with both types of polyps, and 1,037 polyp-free controls. Participants completed a structured interview, and polyps were evaluated via standardized pathology review. We used multivariable polytomous logistic regression to compare case groups with controls and with the other case groups. Factors for which the strength of the association varied significantly between adenomas and serrated polyps were sex (P < 0.001), use of estrogen-only postmenopausal hormone therapy (P = 0.01), and smoking status (P < 0.001). For lesion severity, prior endoscopy (P < 0.001) and age (P = 0.05) had significantly stronger associations with advanced adenomas than with nonadvanced adenomas; and higher education was positively correlated with sessile serrated polyps but not with other serrated polyps (P = 0.02). Statistically significant, site-specific associations were observed for current cigarette smoking (P = 0.05 among adenomas and P < 0.001 among serrated polyps), postmenopausal estrogen-only therapy (P = 0.01 among adenomas), and obesity (P = 0.01 among serrated polyps). These findings further illustrate the epidemiologic heterogeneity of colorectal neoplasia and may help elucidate carcinogenic mechanisms for distinct pathways.

Fatty acids in habitual diet, plasma phospholipids, and tumour and normal colonic biopsies in young colorectal cancer patients

Fatty acid metabolism is altered in colorectal cancer (CRC). We aimed to investigate incorporation of dietary n-6 and n-3 polyunsaturated fatty acids (PUFAs) into plasma phospholipids (PLs), tumour tissue, and normal mucosa in young CRC patients. We also aimed to study differences in PUFA composition between tumour and normal mucosa, and PUFA status associated with cancer stage. Sixty-five CRC patients younger than 55 years were included in a multicenter study. We assessed dietary fatty acid composition by food-frequency questionnaire. Fatty acid composition in plasma PL (n = 65) and tumour and normal colonic biopsies (n = 32) were analysed by gas chromatography. We observed a significant correlation for docosahexaenoic acid (DHA) between dietary intake and concentration in plasma PL (weight%) (r = 0.42; P = 0.001), but not for any n-6 PUFA. Tissue concentrations of arachidonic acid, eicosapentaenoic acid, and DHA (weight%) were 1.7–2.5 times higher in tumour than normal mucosa (P ≤ 0.001). Concentrations of n-3 and n-6 PUFA in plasma PL and tissues were not related to Duke's stage, although patients with more severe cancer stage reported higher intake of n-3 PUFA. In conclusion, we found accumulation of the long-chained n-3 and n-6 PUFA in tumour tissue in young CRC patients.

Body mass index increases risk for colorectal adenomas based on meta-analysis

BACKGROUND & AIMS

There have been inconsistent results published about the relationship between excess body weight, expressed as increased body mass index (BMI), and risk of colorectal adenoma (CRA). We conducted a meta-analysis to explore this relationship. We focused on whether the relationship varied based on the sex of the study subjects, study design, features of the polyps, or potential confounders, including alcohol use, nonsteroidal anti-inflammatory drug use, smoking, and exercise.

METHODS

We identified studies by performing a literature search of Medline, EMBASE, and ISI Web of Science through July 31, 2011, and by searching the reference lists of pertinent articles. We analyzed 36 independent studies, which included 29,860 incident cases of CRA. Summary relative risks with their 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using Cochran's Q statistic and I(2) analyses.

RESULTS

Overall, a 5-unit increase in BMI (calculated as kg/m(2)) increased the risk for CRA (summary relative risk = 1.19; 95% CI: 1.13-1.26), although there was a high level of heterogeneity among studies (P(heterogeneity) < .001; I(2) = 76.8%). Subgroup analyses revealed that the increased risk of CRA in obese individuals was independent of race, geographic location, study design, sex, adenoma progression, and confounders. The association between increased BMI and risk for CRA was stronger for colon than rectal adenoma.

CONCLUSIONS

Based on a meta-analysis, increased BMI increases the risk for colon but not rectal adenoma. Unlike colorectal cancer, there is no sex difference in the relationship between increased BMI and risk of CRA.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Our systematic review has demonstrated that antioxidant supplements may increase mortality. We have now updated this review.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements for prevention of mortality in adults.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index Expanded, and Conference Proceedings Citation Index-Science to February 2011. We scanned bibliographies of relevant publications and asked pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Random-effects and fixed-effect model meta-analyses were conducted. Risk of bias was considered in order to minimise the risk of systematic errors. Trial sequential analyses were conducted to minimise the risk of random errors. Random-effects model meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Seventy-eight randomised trials with 296,707 participants were included. Fifty-six trials including 244,056 participants had low risk of bias. Twenty-six trials included 215,900 healthy participants. Fifty-two trials included 80,807 participants with various diseases in a stable phase. The mean age was 63 years (range 18 to 103 years). The mean proportion of women was 46%. Of the 78 trials, 46 used the parallel-group design, 30 the factorial design, and 2 the cross-over design. All antioxidants were administered orally, either alone or in combination with vitamins, minerals, or other interventions. The duration of supplementation varied from 28 days to 12 years (mean duration 3 years; median duration 2 years). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (21,484 dead/183,749 (11.7%) versus 11,479 dead/112,958 (10.2%); 78 trials, relative risk (RR) 1.02, 95% confidence interval (CI) 0.98 to 1.05) but significantly increased mortality in a fixed-effect model (RR 1.03, 95% CI 1.01 to 1.05). Heterogeneity was low with an I(2)- of 12%. In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. Meta-regression analysis did not find a significant difference in the estimated intervention effect in the primary prevention and the secondary prevention trials. In the 56 trials with a low risk of bias, the antioxidant supplements significantly increased mortality (18,833 dead/146,320 (12.9%) versus 10,320 dead/97,736 (10.6%); RR 1.04, 95% CI 1.01 to 1.07). This effect was confirmed by trial sequential analysis. Excluding factorial trials with potential confounding showed that 38 trials with low risk of bias demonstrated a significant increase in mortality (2822 dead/26,903 (10.5%) versus 2473 dead/26,052 (9.5%); RR 1.10, 95% CI 1.05 to 1.15). In trials with low risk of bias, beta-carotene (13,202 dead/96,003 (13.8%) versus 8556 dead/77,003 (11.1%); 26 trials, RR 1.05, 95% CI 1.01 to 1.09) and vitamin E (11,689 dead/97,523 (12.0%) versus 7561 dead/73,721 (10.3%); 46 trials, RR 1.03, 95% CI 1.00 to 1.05) significantly increased mortality, whereas vitamin A (3444 dead/24,596 (14.0%) versus 2249 dead/16,548 (13.6%); 12 trials, RR 1.07, 95% CI 0.97 to 1.18), vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07), and selenium (2670 dead/39,779 (6.7%) versus 1468 dead/22,961 (6.4%); 17 trials, RR 0.97, 95% CI 0.91 to 1.03) did not significantly affect mortality. In univariate meta-regression analysis, the dose of vitamin A was significantly associated with increased mortality (RR 1.0006, 95% CI 1.0002 to 1.001, P = 0.002).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. Antioxidant supplements need to be considered as medicinal products and should undergo sufficient evaluation before marketing.

Adiposity and the risk of colorectal adenomatous polyps: a meta-analysis

OBJECTIVE

The findings from epidemiological studies addressing the association between adiposity and the risk of colorectal adenomatous polyps are inconsistent. We performed a meta-analysis of epidemiological studies including cross-sectional, case-control, and cohort studies.

METHODS

We searched PubMed and EMBASE in June, 2010. All searched articles were reviewed and selected independently by two evaluators according to pre-determined selection criteria.

RESULTS

We included 25 studies (nine cross-sectional studies, eleven case-control studies, and five prospective cohort studies) that comprised a total of 300,671 participants and 20,903 cases in the final analysis. When all studies were pooled, the odds ratio (OR) or relative risk (RR) of adiposity and abdominal adiposity for colorectal adenomatous polyp risk was 1.43 (95% confidence interval (CI) 1.23-1.67; n = 22) and 1.42 (95% CI 1.30-1.56; n = 12), respectively. Similarly, an increased risk of colorectal adenomatous polyps was observed in most of the subgroup meta-analyses.

CONCLUSIONS

Overall, we found that adiposity and abdominal adiposity significantly increased the risk of colorectal adenomatous polyps in a meta-analysis of epidemiological studies.

FTO polymorphisms are associated with adult body mass index (BMI) and colorectal adenomas in African-Americans

Obesity is a known risk factor for colon cancer and higher body mass index (BMI) has been associated with colorectal adenomas, which are precursor lesions to most colorectal cancers. Polymorphisms in the fat-mass and obesity-associated (FTO) gene have been associated with BMI and larger effects in older versus younger children have been reported. However, no studies have examined associations between FTO polymorphisms, BMI throughout adulthood and colorectal adenomas. Therefore, we evaluated associations between FTO polymorphisms (rs1421085, rs17817449, rs8050136, rs9939609, rs8044769), adult BMI (at recruitment, 50s, 40s, 30s, 20s age decades) and colorectal adenomas in 759 Caucasians and 469 African-Americans. We found that the highest versus the lowest BMI tertile at recruitment [odds ratio (OR) = 1.82; 95% confidence interval (CI): 1.07-2.16] and in the 30s (OR = 1.50; 95% CI: 1.04-2.15) was associated with higher adenoma risk. Stratification by ethnicity revealed that these associations only remained significant in Caucasians. We found that, in Caucasians, having two versus no copies of the variant allele in rs17817449, rs8050136 and rs9939609, which are all in strong linkage disequilibrium, was associated with higher BMI in the 30s and 40s but none of the polymorphisms were associated with adenomas. In African-Americans, having one or two copies of the variant in rs17817449 (OR = 0.61; 95% CI: 0.39-0.95) and rs8050136 (OR = 0.59; 95% CI: 0.38-0.93) was associated with colorectal adenomas and, having two variant copies in rs17817449 and rs8050136 was associated with higher BMI at recruitment and in the 40s, respectively. Our results are consistent with prior studies and show for the first time that FTO polymorphisms are associated with colorectal adenomas in African-Americans.

Metabolic syndrome and its association with colorectal cancer: a review

Currently, significant amount of epidemiologic evidence is present to suggest that metabolic syndrome increases the risk of developing colorectal cancer. This evidence is based on studies of the evaluate determinants of the metabolic syndrome (obesity), clinical consequences of metabolic syndrome (type 2 diabetes and hypertension) and serum component of metabolic syndrome (hypertriglyceridemia, hyperglycemia and low high-density lipoprotein cholesterol), as well as markers of hyperinsulinemia. Although the exact pathogenesis of this relationship is unknown, it seems that hyperinsulinemia may play a pivotal role in increasing CRC risk.

Excess body weight and obesity--the link with gastrointestinal and hepatobiliary cancer

Excess body weight (EBW) is an independent risk factor for many human malignancies, including cancers throughout the gastrointestinal and hepatobiliary tract from the esophagus to the colorectum. The relative risk of gastrointestinal cancer in obese individuals is approximately 1.5-2.0 times that for normal weight individuals, with organ-specific and gender-specific differences for specific cancers. The association between EBW and risk of premalignant stages of gastrointestinal carcinogenesis, such as colorectal adenoma and Barrett esophagus, is similar, implying a role for EBW during the early stages of carcinogenesis that could be relevant to preventative strategies. EBW also impacts negatively on gastrointestinal cancer outcomes. The mechanistic basis of the association between EBW and carcinogenesis remains incompletely understood. Postulated mechanisms include increased insulin and insulin-like growth factor signaling and chronic inflammation (both linked to the metabolic syndrome), as well as signaling via adipokines, such as leptin. The role of obesity-related changes in the intestinal microbiome in gastrointestinal carcinogenesis deserves further attention. Whether weight loss leads to reduced future gastrointestinal and liver cancer risk has yet to be fully explored. There is some support for the idea that weight loss negatively regulates colorectal carcinogenesis. In addition, data suggest a reduction in risk of several cancers in the first 10 years after bariatric surgery.

Body mass index increases risk of colorectal adenomas in men with Lynch syndrome: the GEOLynch cohort study

PURPOSE

High body mass index (BMI) is an established risk factor for sporadic colorectal cancer. Still, the influence of BMI on hereditary colorectal cancer (eg, Lynch syndrome [LS]), is unknown. The objective of this study was to assess whether BMI is associated with colorectal adenoma occurrence in persons with LS.

PATIENTS AND METHODS

A prospective cohort study of 486 patients with LS was conducted. Cox regression models with robust sandwich estimates controlling for age, sex, extent of colon surgery, smoking, and alcohol intake were used to evaluate associations between BMI, height, weight, weight change, and risk of colorectal adenomas. Analyses were performed separately for those without (incident cohort; n = 243) and those with (prevalent cohort; n = 243) a history of colorectal cancer neoplasms at baseline.

RESULTS

A statistically significant association between current overweight (≥ 25 kg/m(2)) and developing colorectal adenomas was seen among men in the incident cohort (overweight v normal weight hazard ratio [HR], 8.72; 95% CI, 2.06 to 36.96). This association was not observed among women (overweight v normal weight HR, 0.75; 95% CI, 0.19 to 3.07), nor was it observed in the prevalent cohort. In the incident cohort, height was statistically significantly associated with a decreased risk of adenomatous polyps among men (per 5 cm HR, 0.43; 95% CI, 0.23 to 0.83), but the association between weight and adenomatous polyps among men was of marginal significance (per 5 kg HR, 1.17; 95% CI, 1.00 to 1.37). No statistically significant associations were observed among women in either the incident cohort or the prevalent cohort.

CONCLUSION

Excess body weight increased the risk of incident colorectal adenomas in people with LS. This increased risk was seen only in men.

Body size, IGF and growth hormone polymorphisms, and colorectal adenomas and hyperplastic polyps

OBJECTIVE

We examined the risk of colorectal polyps in relation to body size factors and candidate polymorphisms in selected genes of insulin-like growth factor (IGF1) (rs5742612), IGF1 receptor (IGF1R) (rs2229765), IGF binding protein 3 (IGFBP3) (rs2854746) and growth hormone (GH1) (rs2665802).

DESIGN

Cases with colorectal adenomas (n=519), hyperplastic polyps (n=691), or both lesions (n=227), and controls (n=772), aged 20-74 years, were recruited from patients who underwent colonoscopy between December 2004 and September 2007 at a large integrated-health plan in Washington state. Subjects participated in a 45-minute telephone interview to ascertain body size and physical activity, and provided a buccal DNA sample for genetic analysis. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable polytomous regression.

RESULTS

Compared to those of normal weight, higher body mass index (BMI) was associated with elevated risk of colorectal adenomas (OR=1.65, 95% CI 1.22-2.25 BMI>or=30 kg/m(2), p-trend=0.002) and both lesions (OR=2.15, 95% CI 1.43-3.22 BMI>or=30 kg/m(2), p-trend=0.003), but there was no relationship with hyperplastic polyps. Obesity at age 18 and a weight gain of >or=21 kg since age 18 were also significantly associated with an increased risk of colorectal adenomas and both lesions, but not hyperplastic polyps. There was a reduced risk of colorectal adenomas (OR=0.63, 95% CI 0.42-0.94) and hyperplastic polyps (OR=0.7, 95% CI 0.5-0.9) associated with the homozygous variant genotype for GH1. Few meaningful results were evident for the other polymorphisms.

CONCLUSIONS

There is an increased risk of colorectal adenomas and presence of both adenomas and hyperplastic polyps in relation to increasing body size. Some genetic variation in GH1 might contribute to a reduced risk of colorectal adenomas and hyperplastic polyps.

Time from positive screening fecal occult blood test to colonoscopy and risk of neoplasia

There is no guideline defining the optimal time from a positive screening fecal occult blood test to follow-up colonoscopy. We reviewed records of 231 consecutive primary care patients who received a colonoscopy within 18 months of a positive fecal occult blood test. We examined the relationship between time to colonoscopy and risk of neoplasia on colonoscopy using a logistic regression analysis adjusting for potential confounders such as age, race, and gender. The mean time to colonoscopy was 236 days. Longer time to colonoscopy (OR = 1.10, P = 0.01) and older age (OR 1.04, P = 0.01) were associated with higher odds of neoplasia. The association of time with advanced neoplasia was positive, but not statistically significant (OR 1.07, P = 0.14). In this study, a longer interval to colonoscopy after fecal occult blood test was associated with an increased risk of neoplasia. Determining the optimal interval for follow-up is desirable and will require larger studies.

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

To examine whether BMI is independently related to colorectal adenomas and hyperplastic polyps.

METHODS

We conducted a cross-sectional study among 1,420 asymptomatic women aged 40-79 years who had undergone complete colonoscopy. Logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI) of adenomas and hyperplastic polyps.

RESULTS

We identified 953 women (67.1%) with no polyps, 292 (20.6%) with adenomas, and 175 (12.3%) with hyperplastic polyps. Among those with polyps, 75 women (5.3% of total women) were classified as having both adenomas and hyperplastic polyps. After adjusting for potential risk factors for colorectal cancer, BMI was related to increased risk of adenomas (OR comparing obese to normal weight women = 1.57; 95% CI = 1.07-2.29). Further, BMI was associated with enhanced risk of hyperplastic polyps (OR = 3.76; 95% CI = 2.35-6.01) and the combination of adenomas and hyperplastic polyps (OR = 2.84; 95% CI = 1.41-5.72).

CONCLUSIONS

Excess body mass is positively related to colorectal adenomas and hyperplastic polyps, particularly when both kinds of polyps are present in combination. Future studies should continue to delineate the possible differences in potential risk factors between colorectal adenomas and hyperplastic polyps. Such work should help further elucidate the possible causes of colorectal cancer.

Obesity is associated with an increased prevalence of advanced adenomatous colon polyps in a male veteran population

Obesity has been associated with an increased risk for colonic adenomatous polyps (APs) and colorectal cancers, but the influence of obesity on the development of advanced APs is not clear. The purpose of this study is to determine the influence of obesity on the prevalence of advanced APs in a male veteran population. We performed a retrospective study of patients (n = 2,903) with histologically confirmed APs on an index colonoscopy. APs were evaluated for advanced features (size > or = 1 cm in diameter and/or a villous component and/or high grade dysplasia). Patients were categorized as: normal weight (BMI > 18.5 and < 25), overweight (BMI > or = 25 and < 30), and obese (BMI > or = 30). An association between clinical factors and advanced APs was sought by Kruskal-Wallis test and Pearson Chi-square. Multiple logistic regression analysis was used to determine independent predictors for advanced APs. We identified 2,903 male patients with APs (mean age 64 + 1.1(SE) years; 770 (27%) normal weight, 1,029 (35%) overweight, 1,104 (38%) obese. By univariate analysis, obese patients had a greater prevalence of advanced APs than the overweight and normal weight patients (28 vs. 23 vs. 24%, p = 0.025). Multiple logistic regression analysis confirmed the association of obesity and advanced APs (OR = 1.01, CI = 1-1.02, p = 0.04). For every one-unit increase in BMI above 30, there was a corresponding 1% increase in the frequency of finding advanced APs. Obesity in male veteran patients is associated with the finding of advanced APs on colonoscopy. We speculate that obesity may increase the risk for CRC by promoting the development of advanced APs.

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

To examine whether BMI is independently related to colorectal adenomas and hyperplastic polyps.

METHODS

We conducted a cross-sectional study among 1,420 asymptomatic women aged 40-79 years who had undergone complete colonoscopy. Logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI) of adenomas and hyperplastic polyps.

RESULTS

We identified 953 women (67.1%) with no polyps, 292 (20.6%) with adenomas, and 175 (12.3%) with hyperplastic polyps. Among those with polyps, 75 women (5.3% of total women) were classified as having both adenomas and hyperplastic polyps. After adjusting for potential risk factors for colorectal cancer, BMI was related to increased risk of adenomas (OR comparing obese to normal weight women = 1.57; 95% CI = 1.07-2.29). Further, BMI was associated with enhanced risk of hyperplastic polyps (OR = 3.76; 95% CI = 2.35-6.01) and the combination of adenomas and hyperplastic polyps (OR = 2.84; 95% CI = 1.41-5.72).

CONCLUSIONS

Excess body mass is positively related to colorectal adenomas and hyperplastic polyps, particularly when both kinds of polyps are present in combination. Future studies should continue to delineate the possible differences in potential risk factors between colorectal adenomas and hyperplastic polyps. Such work should help further elucidate the possible causes of colorectal cancer.

Gastrointestinal endoscopy nurse experience and polyp detection during screening colonoscopy

BACKGROUND & AIMS

The effect of gastrointestinal endoscopy nursing experience on polyp detection is unknown. The aim of this study was to determine whether nurse experience is associated with odds of polyp detection.

METHODS

We performed a retrospective analysis of screening colonoscopies performed by attendings at University of North Carolina hospitals between August 2003 and 2005. Nurse experience was dichotomized at 6 months. The primary outcome was polyp detection, with secondary analysis by histologic type. Descriptive statistics, bivariate analysis, and multivariable logistic regression were performed.

RESULTS

Any polyp was detected in 44% of the eligible 3631 colonoscopies. Multiple polyps were detected in 23%, adenomas in 25%, advanced lesions in 5%, and hyperplastic polyps in 11%. Twenty-nine nurses were employed during the study period, 19 of whom were new to endoscopy nursing. For nurses with 6 months of experience or less, any polyp was detected in 40.3% of procedures compared with 46.0% of procedures for nurses with more than 6 months of experience (odds ratio [OR], 1.26; 95% confidence interval [CI], 1.09-1.46). Similar results were seen for multiple polyps (OR, 1.54; 95% CI, 1.29-1.84) and hyperplastic polyps (OR, 1.47; 95% CI, 1.22-1.76), but not for adenomas (OR, 1.10; 95% CI, 0.93-1.30) or advanced lesions (OR, 0.99; 95% CI, 0.71-1.36). These relationships were unchanged after adjusting for potential confounding patient and procedure variables.

CONCLUSIONS

Procedures staffed by less-experienced gastrointestinal endoscopy nurses have increased odds of not detecting polyps. Subanalysis suggests that detection of hyperplastic polyps explains much of this relationship.

Factors that increase risk of colon polyps

Adenomatous polyps are common and factors that increase risk include race, gender, smoking, and obesity. This author summarizes the evidence supporting increased risk with these factors and describes how epidemiological data may be used to tailor screening programs.

Prospective weight change and colon cancer risk in male US health professionals

Epidemiological studies are remarkably consistent, especially among men, in showing that overweight and obesity [body mass index (BMI) >25] are associated with increased risk of colon cancer. However, no prospective studies address the influence of weight change in adulthood on subsequent colon cancer risk. In this study, we investigated whether weight change influences colon cancer risk utilizing prospectively collected weight data. We included 46,349 men aged 40-75 participating in the Health Professionals Follow-Up Study. Questionnaires including items on weight were completed every second year during follow-up from 1986 to 2004. Updated weight change between consecutive questionnaires during follow-up and recalled weight gain since age 21 was evaluated. All eligible men were cancer-free at baseline. Proportional hazard and restricted spline regression models were implemented. Over an 18-year period, we documented 765 cases of colon cancer. Cumulative mean BMI >22.5 was associated with significantly increased risk of colon cancer. The short-term weight change in the prior 2 to 4 years was positively and significantly associated with risk [HR = 1.14 (95% confidence interval, 1.00-1.29) for 4.54 kg (10 pounds) increment, p = 0.04 for overall trend]. Weight gain per 10 years since age 21 was associated with significantly increased risk [HR = 1.33 (1.12-1.58) for 4.54 kg increase per 10 years, p = 0.001]. We estimated that 29.5% of all colon cancer cases was attributable to BMI above 22.5. Our results add support that overweight and obesity are modifiable risk factors for colon cancer among men and suggest that weight has an important influence on colon cancer risk even in later life.

Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

BACKGROUND

Animal and physiological research as well as observational studies suggest that antioxidant supplements may improve survival.

OBJECTIVES

To assess the effect of antioxidant supplements on mortality in primary or secondary prevention randomised clinical trials.

SEARCH STRATEGY

We searched The Cochrane Library (Issue 3, 2005), MEDLINE (1966 to October 2005), EMBASE (1985 to October 2005), and the Science Citation Index Expanded (1945 to October 2005). We scanned bibliographies of relevant publications and wrote to pharmaceutical companies for additional trials.

SELECTION CRITERIA

We included all primary and secondary prevention randomised clinical trials on antioxidant supplements (beta-carotene, vitamin A, vitamin C, vitamin E, and selenium) versus placebo or no intervention. Included participants were either healthy (primary prevention trials) or had any disease (secondary prevention trials).

DATA COLLECTION AND ANALYSIS

Three authors extracted data. Trials with adequate randomisation, blinding, and follow-up were classified as having a low risk of bias. Random-effects and fixed-effect meta-analyses were performed. Random-effects meta-regression analyses were performed to assess sources of intertrial heterogeneity.

MAIN RESULTS

Sixty-seven randomised trials with 232,550 participants were included. Forty-seven trials including 180,938 participants had low risk of bias. Twenty-one trials included 164,439 healthy participants. Forty-six trials included 68111 participants with various diseases (gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified). Overall, the antioxidant supplements had no significant effect on mortality in a random-effects meta-analysis (relative risk [RR] 1.02, 95% confidence interval [CI] 0.99 to 1.06), but significantly increased mortality in a fixed-effect model (RR 1.04, 95% CI 1.02 to 1.06). In meta-regression analysis, the risk of bias and type of antioxidant supplement were the only significant predictors of intertrial heterogeneity. In the trials with a low risk of bias, the antioxidant supplements significantly increased mortality (RR 1.05, 95% CI 1.02 to 1.08). When the different antioxidants were assessed separately, analyses including trials with a low risk of bias and excluding selenium trials found significantly increased mortality by vitamin A (RR 1.16, 95% CI 1.10 to 1.24), beta-carotene (RR 1.07, 95% CI 1.02 to 1.11), and vitamin E (RR 1.04, 95% CI 1.01 to 1.07), but no significant detrimental effect of vitamin C (RR 1.06, 95% CI 0.94 to 1.20). Low-bias risk trials on selenium found no significant effect on mortality (RR 0.91, 95% CI 0.76 to 1.09).

AUTHORS' CONCLUSIONS

We found no evidence to support antioxidant supplements for primary or secondary prevention. Vitamin A, beta-carotene, and vitamin E may increase mortality. Future randomised trials could evaluate the potential effects of vitamin C and selenium for primary and secondary prevention. Such trials should be closely monitored for potential harmful effects. Antioxidant supplements need to be considered medicinal products and should undergo sufficient evaluation before marketing.

Leptin concentrations, leptin receptor polymorphisms, and colorectal adenoma risk

Obesity has been shown to be associated with an increased risk of both colorectal cancer and adenomatous polyps. One mechanism underlying this relationship may involve the growth-promoting effects of the circulating hormones associated with obesity, such as leptin. We conducted a gastroenterology clinic-based, case-control study to evaluate the relationship between circulating leptin concentrations and colorectal adenoma risk; in addition, we evaluated the relationship between leptin receptor polymorphisms and adenoma risk. Individuals with adenomas (n = 157) and colonoscopy-negative controls (n = 191), who had a clinically indicated colonoscopy, were recruited from a large health maintenance organization in the Seattle metropolitan area from 1999 to 2003. Odds ratios and 95% confidence intervals were obtained using logistic regression, adjusting for age at diagnosis, body mass index, family history of colorectal cancer, smoking history, nonsteroidal anti-inflammatory drug use, physical activity, and, among women, menopausal status and postmenopausal hormone use. Among men, those in the highest tertile of leptin concentrations had a 3.3-fold (95% confidence interval, 1.2-8.7) increased adenoma risk compared with those in the lowest tertile (P trend = 0.01). There were no associations between leptin concentrations and adenoma risk in women. There were no associations of leptin receptor genotypes or haplotypes and adenoma risk. The results of this study suggest that, in men, leptin may be associated with risk of colorectal adenomas.

Visceral obesity as a risk factor for colorectal neoplasm

BACKGROUND AND AIM

Obesity as a risk factor for colorectal neoplasm (CRN) is controversial. In the present study, we evaluated visceral obesity as a risk factor for CRN.

METHODS

We prospectively enrolled 200 consecutive, asymptomatic adults (male : female = 133:67, mean age, 50.9 +/- 8.5 years) undergoing both colonoscopy and abdominopelvic computed tomography (CT) scan for routine health evaluations. The presence or absence and the characteristics of CRN were determined during colonoscopy. The amount of visceral adipose tissue (VAT) and subcutaneous adipose tissue was measured by an abdominopelvic CT scan. Body mass index, waist circumference, and percentage of body fat were measured. Blood pressure and other blood markers for assessing the metabolic syndrome were also investigated.

RESULTS

Of the 200 patients, 53 (26.5%) had CRN. Old age, smoking, metabolic syndrome, and a high fasting plasma glucose level were associated with an increased risk of CRN. VAT (P < 0.01) and waist circumference (P = 0.01) were significantly higher in those with CRN. A multivariate analysis of the risks of CRN showed an odds ratio of 4.07 (95% confidence interval: 1.01-16.43, P = 0.03) for those with VAT over 136.61 cm(2) relative to those with VAT under 67.23 cm(2). Waist circumference, metabolic syndrome, and fasting plasma glucose levels were not independent risk factors for CRN in the multivariate analysis.

CONCLUSION

Increased VAT is an independent risk factor for CRN. Further large scale studies are needed to clarify the causal relationship between VAT and CRN.

Physical activity before and after diagnosis of colorectal cancer: disease risk, clinical outcomes, response pathways and biomarkers

Physical inactivity may be responsible for 13-14% of colon cancer, an attributable risk greater than family history. Epidemiological evidence shows an association between occupational and recreational physical activity and colon cancer, but has not established whether physical activity is protective against low-risk or more advanced adenomas. The evidence is inconclusive as to whether physical activity protects against rectal cancer and is conflicting with respect to whether physical activity has equal effects on male and female risk of colorectal cancer. The effect of exercise 'interventions' on the risk of colorectal cancer is currently not known. Also, although inferences can be made from epidemiological studies, no optimal exercise regimen can be confidently prescribed for protection against colorectal cancer. There is little available evidence for the benefits of physical activity before diagnosis of colorectal cancer for disease-specific survival and prognosis, and the clinical effects of an exercise intervention after diagnosis have not been investigated. There is some evidence that improvements in cardiorespiratory fitness reduce adverse effects from cancer treatment when physical activity is undertaken following diagnosis of colorectal cancer. Markers/mechanisms by which physical activity may protect against colorectal cancer and/or improve disease prognosis include gastrointestinal transit-time, chronic inflammation, immune function, insulin levels, insulin-like growth factors, genetics and obesity. Research evidence is, however, limited as to whether these markers are beneficially affected by physical activity, either before or after diagnosis of colorectal cancer.

Metabolic syndrome, hyperinsulinemia, and colon cancer: a review

An impressive body of epidemiologic data collected over the past decade indicates that the risk of colon cancer is elevated in those with metabolic syndrome. This evidence includes studies that examined the risk of colon cancer or adenoma in relation to determinants of the metabolic syndrome (obesity, abdominal distribution of adiposity, and physical inactivity), clinical consequences of this syndrome (type 2 diabetes and hypertension), plasma or serum components of the definition of metabolic syndrome (hypertriglyceridemia, hyperglycemia, and low HDL cholesterol), and markers of hyperinsulinemia or insulin resistance (insulin and C-peptide), which is the underlying metabolic defect of the metabolic syndrome. The mechanism underlying these associations is unknown but may involve the influence of hyperinsulinemia in enhancing free or bioavailable concentrations of insulin-like growth factor-1. Future studies should also be based on better measurements of insulin resistance, beta-cell depletion, and insulin responses to better assess which aspects of insulin resistance are most closely related to the risk of colon neoplasia.

Obesity and colorectal cancer risk: A meta-analysis of cohort studies

AIM: To evaluate the association between obesity and colorectal cancer risk.

METHODS: We searched PubMed, EMBASE, and the Cochrane Library up to January 1, 2007. Cohort studies permitting the assessment of causal association between obesity and colorectal cancer, with clear definition of obesity and well-defined outcome of colorectal cancer were eligible. Study design, sample size at baseline, mean follow-up time, co-activators and study results were extracted. Pooled standardized effect sizes were calculated.

RESULTS: The pooled relative risk (RR) of colorectal cancer was 1.37 (95% CI: 1.21-1.56) for overweight and obese men, 1.07 (95% CI: 0.97-1.18) for women measured by body mass index (BMI). The pooled RR for the highest vs the lowest quantiles of BMI was 1.59 (95% CI: 1.35-1.86) for men and 1.22 (95% CI: 1.08-1.39) for women at risk of colon cancer, 1.16 (95% CI: 0.93-1.46) for men and 1.23 (95% CI: 0.98-1.54) for women at risk of rectal cancer. The pooled RR for the highest vs the lowest quantiles of waist circumference was 1.68 (95% CI: 1.36-2.08) for men and 1.48 (95% CI: 1.19-1.84) for women at risk of colon cancer, 1.26 (95% CI: 0.90-1.77) for men and 1.23 (95% CI: 0.81-1.86) for women at risk of rectal cancer. The pooled RR for the highest quantiles vs the lowest quantiles of waist-to-hip ratio was 1.91 (95% CI: 1.46-2.49) for men and 1.49 (95% CI 1.23-1.81) for women at risk of colon cancer, 1.93 (95% CI: 1.19-3.13) for men and 1.20 (95% CI: 0.81-1.78) for women at risk of rectal cancer. Compared with 'normal range', the pooled RR for proximal colon cancer was 1.14 (95% CI : 0.88-1.47) for the overweight and 1.41 (95% CI: 0.66-3.01) for the obese. The pooled RR for the highest quantiles vs the lowest quantiles was 2.05 (95% CI: 1.23-3.41) with waist circumference, 1.66 (95% CI: 0.69-3.99) with waist-to-hip ratio. Compared with 'normal range', the pooled RR for distal colon cancer was 1.38 (95% CI: 1.02-1.87) for the overweight and 1.23 (95% CI: 0.80-1.90) for the obese. The pooled RR for the highest quantiles vs the lowest quantiles was 1.86 (95% CI: 1.05-3.30) with waist circumference, and 1.79 (95% CI: 0.82-3.90) with waist-to-hip ratio.

CONCLUSION: Obesity is a statistically significant risk factor for colorectal cancer and the relationship is more significant in men than in women among different cancer subsites. Indexes of abdominal obesity are more sensitive than those of overall obesity.

Association between body size and colorectal adenoma recurrence

BACKGROUND & AIMS

Obesity has been associated with increased risk for colorectal adenoma, although its role as a risk factor after polypectomy for recurrence is unclear. Therefore, we sought to evaluate the effect of anthropometric measures of obesity on adenoma after polypectomy.

METHODS

Subjects with baseline adenomas (n = 2465) and follow-up colonoscopy data were drawn from 2 randomized trials designed to prevent adenoma recurrence.

RESULTS

Over a mean follow-up period of 3.1 years presence of a body mass index (BMI) > or = 30 kg/m2 was associated with a nonsignificant 17% increase in the odds for any adenoma recurrence among all subjects (odds ratio [OR], 1.17; 95% confidence interval [CI], 0.92-1.48). This result was confined to men (OR, 1.36; 95% CI, 1.01-1.83) and not observed for women (OR, 0.90; 95% CI, 0.60-1.33). Results for waist circumference did not reach statistical significance, although trends were similar to those for BMI. Analyses of the effects of obesity on more clinically significant lesions demonstrated that high BMI was a slightly stronger risk factor for advanced adenoma recurrences in men (OR, 1.62; 95% CI, 1.04-2.53) when compared with non-advanced lesions (OR, 1.26; 95% CI, 0.91-1.75). In addition, we observed an association for obesity and odds of adenoma recurrence among participants reporting a family history of colorectal cancer (OR, 2.25; 95% CI, 1.32-3.84) but not for those without (OR, 1.00; 95% CI, 0.77 to 1.31; P(int) = P = .008).

CONCLUSIONS

Our results support obesity as a risk factor for subsequent short-interval (mean follow-up time 3.1 years) development of colorectal adenomas, particularly among men and persons with a family history of colorectal cancer. Furthermore, obesity in men appears to be strongly associated with the development of clinically advanced lesions.

Change in body size and the risk of colorectal adenomas

Adiposity has been recognized as a risk factor for colorectal adenoma, but the influence of weight gain, adipose tissue distribution, and possible differences between ethnic/racial and gender groups remains unanswered. The aim of this prospective study was to examine the association between adiposity and weight change and colorectal adenoma risk. Over approximately 10-year period, anthropometric measures and other risk factors were measured at three time points in the multicenter multiethnic Insulin Resistance Atherosclerosis Study cohort. Colonoscopies were then conducted on 600 cohort participants regardless of symptoms whose mean age at colonoscopy was 64 years. Multivariate logistic regression analyses were used to assess the association between colorectal adenomas and measures of adiposity and weight change over the approximately 10-year period before colonoscopy. Obesity was positively associated with risk of colorectal adenomas at the time of colonoscopy [adjusted odds ratio (OR(adj)), 2.16; 95% confidence interval (95% CI), 1.13-4.14] and was stronger in women (OR(adj), 4.42; 95% CI, 1.53-12.78) than in men (OR(adj), 1.26; 95% CI, 0.52-3.07). The risk of adenomas increased among participants who gained weight compared with those who maintained weight over the approximately 5 years (OR(adj), 2.30; 95% CI, 1.25-4.22) and approximately 10 years (OR(adj), 2.12; 95% CI, 1.25-3.62). These associations were similar for both advanced and nonadvanced adenomas. These results suggest a positive association between obesity, weight gain, and colorectal adenoma risk. Stronger associations were observed when obesity was measured at the time of colonoscopy, suggesting that obesity may be a promoting factor in the growth of colorectal adenomas.

The role of obesity and related metabolic disturbances in cancers of the colon, prostate, and pancreas

Recent evidence indicates that obesity and related metabolic abnormalities are associated with increased incidence or mortality for a number of cancers, including those of the colon, prostate, and pancreas. Obesity, physical inactivity, visceral adiposity, hyperglycemia, and hyperinsulinemia are relatively consistent risk factors for colon cancer and adenoma. Also, patients with type 2 diabetes mellitus have a higher risk of colon cancer. For prostate cancer, the relationship to obesity appears more complex. Obesity seems to contribute to a greater risk of aggressive or fatal prostate cancer but perhaps to a lower risk of nonaggressive prostate cancer. Furthermore, men with type 2 diabetes mellitus are at lower risk of developing prostate cancer. Long-standing type 2 diabetes increases the risk of pancreatic cancer by approximately 50%. Furthermore, over the past 6 years, a large number of cohort studies have reported positive associations between obesity and pancreatic cancer. Together with data from prediagnostic blood specimens showing positive associations between glucose levels and pancreatic cancer up to 25 years later, sufficient evidence now supports a strong role for diabetes and obesity in pancreatic cancer etiology. The mechanisms for these associations, however, remain speculative and deserve further study. Hyperinsulinemia may be important, but the role of oxidative stress initiated by hyperglycemia also deserves further attention.

Aspirin may be more effective in preventing colorectal adenomas in patients with higher BMI (United States)

Obesity is a risk factor for colon cancer, possibly due to elevated levels of circulating cytokines derived from adipose tissue. Aspirin, which may affect the levels of these cytokines, has been shown in randomized controlled trials to decrease the risk of colorectal adenomas. We hypothesized that the chemopreventive effect of aspirin might be greater in individuals with higher body mass index (BMI). Data were available from the Aspirin/Folate Polyp Prevention Study, a randomized controlled trial of aspirin and folic acid to prevent recurrent colorectal adenomas. Obesity was defined as BMI > or = 30 (kg/m2), overweight as BMI of 25-29 (kg/m2) and normal weight as BMI <25 (kg/m2). For the analysis of the effect of aspirin on the recurrence of colorectal adenoma by BMI, we computed risk ratios for aspirin versus placebo within the three BMI strata using a modified Poisson model. Overall the risk reduction of adenomas with a daily dose of 325 mg aspirin was greater among subjects with higher BMI. Among obese subjects the risk ratio (RR) for advanced adenomas compared with placebo was 0.44 (95% CI 0.17-1.10), versus RR = 1.23 (95% CI 0.55-2.77) among those with normal weight. However, 81 mg aspirin daily did not interact with BMI to modify the risk of adenomas in such a fashion. The more pronounced effect of 325 mg aspirin in individuals with higher BMI suggests a possible protective role of anti-inflammatory aspirin against increased adipose-driven cytokines among obese subjects.

Lifestyle as a predictor for colonic neoplasia in asymptomatic individuals

Background

Lifestyle is a well-established risk factor for colorectal cancer (CRC) and is also found to be associated with occurrence of adenomas. In the present study we evaluated risk factors for both low-risk adenomas and advanced neoplasia in asymptomatic individuals using a single-paged questionnaire. Aiming to see if the questionnaire was a useful tool in picking up high-risk individuals.

Methods

A cross-sectional study was carried out within a randomised controlled colorectal cancer screening trial (n = 6961). The population comprised men and women born between 1946 and 1950. Before screening in year 2001 they were asked to fill in a questionnaire about their present lifestyle. Cases were categorised according to the most severe findings at screening. Analyses were then conducted to find risk factors associated with the presence of either low-risk adenomas or advanced neoplasia.

Results

The response rate among attendees was 97% (3998/4111). Among these, 3447 (86%) had no neoplasia, 443 (11%) had low-risk adenomas, and 108 (3%) had advanced neoplasia. Low-risk adenomas were significantly associated with current smoking, and obesity. Participants with advanced neoplasia had a two-fold increased risk of not adhering to any of the selected lifestyle recommendations compared to controls. However, current smoking was the only variable that reached statistical significance in the multivariate analysis for these lesions. A dose-response relationship to the consumption of cigarettes per day was shown, where OR was 2.04 (CI 1.07–3.89) for the lowest consumption category.

Conclusion

The present findings indicate that a short questionnaire may be adequate in picking up the most consistent associations between lifestyle risk factors and colorectal neoplasia. Smoking and BMI were found to be the most significant risk factors for neoplasia, but adhering to recommendations on diet, and physical activity seems also to be of importance.

The association of physical activity and body mass index with the risk of large bowel polyps

PURPOSE AND METHOD

Several studies have suggested that physical inactivity and obesity increase the risk for colorectal neoplasia. In this study, we investigated the association of physical activity and body mass index (BMI) with the risk of different types of large bowel polyps. We did an observational analysis nested within a randomized double-blind placebo-controlled chemoprevention trial among patients with one or more recently resected histologically confirmed colorectal adenoma. Nine hundred thirty patients were randomized to calcium (1,200 mg/d, as carbonate) or placebo. Follow-up colonoscopies were conducted approximately 1 and 4 years after the qualifying examination. At study entry, we obtained each subject's current body weight and height, which we used to calculate BMI. After the second study colonoscopy, we asked subjects questions about their leisure time physical activity. Seven hundred eighty-seven subjects completed at least part of the physical activity questionnaire.

RESULTS

We found no association between measures of physical activity or BMI and tubular adenomas or hyperplastic polyps. However, among men, there were strong inverse associations observed between physical activity and advanced neoplastic polyps. Compared with men whose total daily energy expenditure was in the lowest tertile, those in the highest tertile had a risk ratio of 0.35 (95% confidence interval, 17-0.72); there was no similar reduction observed among women (risk ratio, 1.21; 95% confidence interval, 0.36-4.03; P for interaction = 0.04).

DATA INTERPRETATIONS

We found a significant inverse relationship between several measures of physical activity and risk of advanced colorectal neoplasms, particularly among men. No associations were found between BMI and hyperplastic polyps, tubular adenomas, or advanced neoplastic polyps.

Glycemic Index, Glycemic Load, and Carbohydrate Intake in Relation to Risk of Distal Colorectal Adenoma in Women

Case-control studies and a cohort study have shown inconsistent associations between a high glycemic index or a high glycemic load and risk of colorectal cancer. These dietary variables have not been examined in relation to risk of colorectal adenoma. We thus examined the associations between dietary glycemic index, glycemic load, and carbohydrate intake with risk of adenoma of the distal colon or rectum among 34,428 US women who were initially free of cancer or polyps, who completed a semi-quantitative food-frequency questionnaire in 1980, and who underwent endoscopy from 1980 through 1998. 1,715 adenoma cases (704 large adenomas, 894 small adenomas, 1,277 distal colon adenomas, and 504 rectal adenomas) were documented during 18 years of follow-up. Dietary glycemic index, glycemic load, and carbohydrate intake were not related to risk of total colorectal adenoma after adjustment for age and established risk factors [relative risk (RR) for extreme quintiles of glycemic index = 1.11, 95% confidence interval (CI) 0.94-1.32, P for trend = 0.66; RR for glycemic load = 0.92, 95% CI 0.76-1.11, P for trend = 0.63; RR for carbohydrate intake = 0.90, 95% CI 0.73-1.11, P for trend = 0.64]. In addition, no significant associations were found for large or small adenoma, distal colon or rectal adenoma, or across strata of body mass index. Our findings do not support the hypothesis that a high glycemic index diet, a high glycemic load diet, or high carbohydrate intake overall are associated with risk of colorectal adenoma.

Relationship of visceral adipose tissue to recurrence of adenomatous polyps

OBJECTIVES

Insulin is a growth factor for colorectal cancer. Visceral adipose tissue (VAT) is strongly associated with insulin levels, and insulin and visceral obesity have been associated in cohort studies with colorectal cancer. The aim of this investigation was to determine whether VAT is associated with recurrence of adenomatous polyps, the precursor to colorectal cancer.

METHODS

As an ancillary study to the Polyp Prevention Trial, a randomized clinical trial that evaluated the effect of a low-fat, high-fiber, high vegetable and fruit diet on adenomatous polyp recurrence, subjects at one clinical center underwent measurement of VAT with a single-slice CT scan through the L4-L5 interspace. The scan was performed around the time of the subject's year 4 colonoscopy that determined adenoma recurrence.

RESULTS

Of 119 subjects, 44 of 84 men (52%) and 16 of 35 women (46%) had a recurrent adenoma (p= 0.51). Body mass index (BMI) and weight at baseline and at year 4 colonoscopy were unrelated to adenoma recurrence. In a multivariate model including visceral fat quartile, remote history of polyps, gender, age, and randomization group, only remote history of polyps was statistically significantly associated with recurrent adenoma with a relative risk of 4.6 (95% CI 1.7, 12.4, p= 0.001). There was no consistent monotonic trend of increased or decreased risk of recurrence as one ascended quartiles of adipose tissue for visceral, subcutaneous, or total abdominal fat.

CONCLUSION

In this study, no association between visceral adipose tissue and adenomatous polyp recurrence was observed. Further study and exploration of the role of VAT in adenoma progression is required.