Obesity and colorectal adenomatous polyps

Colorectal Cancer Risk Is Impacted by Sex and Type of Surgery After Bariatric Surgery

PURPOSE

Sex differences exist in the associations between obesity and the risk of colorectal cancer (CRC). However, limited data exist on how sex affects CRC risk after bariatric surgery.

MATERIALS AND METHODS

This retrospective cohort study used the 2012-2020 MarketScan database. We employed a propensity-score-matched analysis and precise coding to define CRC in this nationwide US study. Adjusted hazards ratio (HR) assessed CRC risk ≥ 6 months. In a restricted analysis, logistic regression with adjusted odds ratios (OR) examined CRC risk ≥ 3 years.

RESULTS

Our sample included 327,734 controls with severe obesity and 88,630 patients with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (VSG). The odds of cessation of diabetes mellitus medications, a surrogate for diabetes remission, were higher post-surgery vs. controls, especially in RYGB and males. In females, CRC risk decreased post-RYGB compared to controls (HR = 0.40, 95%CI: 0.18-0.87, p = 0.02). However, VSG was not associated with lower CRC risk in females. Paradoxically, in males compared to controls, CRC risk trended toward an almost significant increase, especially after 3 years or more from surgery (OR = 2.18, 95%CI: 0.97-4.89, p = 0.06). Males had a higher risk of CRC, particularly rectosigmoid cancer, than females after bariatric surgery (HR = 2.69, 95% CI: 1.35-5.38, p < 0.001). Furthermore, diabetes remission was not associated with a lower CRC risk post-surgery.

CONCLUSION

Our data suggest an increased risk of CRC in males compared to females after bariatric surgery. Compared to controls, there was a decrease in CRC risk in females' post-RYGB but not VSG. Mechanistic studies are needed to explain these differences.

OUP accepted manuscript

Background

Although obesity is a known risk factor, the impact of weight change on colorectal adenoma risk is less clear and could have important implications in disease prevention. We prospectively evaluated weight change in adulthood and incident colorectal adenoma.

Methods

We assessed weight change during early-late (age 20 years to baseline, ie, ages 55-74 years), early-middle (20-50 years), and middle-late (50 years-baseline) adulthood using self-reported weight data in relation to incident distal adenoma in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (cases = 1053; controls = 16 576). For each period, we defined stable weight as greater than −0.5 kg to less than or equal to 1 kg/5 years, weight loss as less than or equal to −0.5 kg/5 years, and weight gain as greater than 1-2, greater than 2-3, or greater than 3 kg/5 years. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using logistic regression; all tests were 2-sided.

Results

Compared with stable weight, weight loss during early-late adulthood was associated with reduced adenoma risk (OR = 0.54, 95% CI = 0.34 to 0.86), particularly among those who were overweight or obese at age 20 years (OR = 0.39, 95% CI = 0.18 to 0.84). Results were similar for early-middle adulthood but less pronounced for middle-late adulthood. Weight gain greater than 3 kg/5 years during early-late adulthood was associated with increased risk (OR = 1.30, 95% CI = 1.07 to 1.58, P_trend < .001). Findings appeared stronger among men (OR for >3 kg/5 years = 1.41, 95% CI = 1.11 to 1.80) than women (OR = 1.09, 95% CI = 0.79 to 1.50, P_interaction = .21).

Conclusions

Weight loss in adulthood was associated with reduced adenoma risk, particularly for those who were overweight or obese, whereas weight gain greater than 3 kg/5 years increased risk. Findings underscore the importance of healthy weight maintenance throughout adulthood in preventing colorectal adenoma.

Disparate age and sex distribution of sessile serrated lesions and conventional adenomas in an outpatient colonoscopy population-implications for colorectal cancer screening?

PURPOSE

Colorectal cancer (CRC) is increasingly diagnosed in individuals aged < 50 years, resulting in advocacy of screening from age 45 years. Despite existing knowledge associating CRC with conventional adenomas, the significance of sessile serrated lesions (SSLs) on the burden of CRC is less detailed. We aimed to provide contemporary estimates for SSL prevalence and examine patient and procedure factors associated with SSL detection.

METHODS

Retrospective observational study examining associations between SSL and conventional adenoma detection, polyp histopathology, patient, and procedure characteristics in an outpatient colonoscopy unit over 12 months.

RESULTS

From 2097 colonoscopies, SSL detection was 13.8% overall and 12.5% in patients < 50 years. SSLs were mostly proximal in location (64%), and SSL detection was significantly higher in females compared with males (16.2% vs. 11.7%, p = 0.003), particularly in those < 50 years (16.8% vs. 8.6%, p < 0.001). In multivariable analysis, SSL detection was associated with female sex (adjusted odds ratio [aOR] 1.48, 95% confidence interval [CI] 1.15-1.91), synchronous conventional adenoma detection (aOR 1.36, 95% CI 1.04-1.78) and BMI ≥ 25 kg/m² (aOR 1.34, 95% CI 1.02-1.77). Conventional adenoma detection was 33.6% and associated with age ≥ 50 years (aOR 3.57, 95% CI 2.84-4.47) and synchronous SSL detection (aOR 1.36, 95% CI 1.03-1.79).

CONCLUSIONS

We observed age and sex disparities in polyp types and prevalence in this outpatient colonoscopy population. SSLs were most prevalent in females aged < 50 years, suggesting a potential increased susceptibility of young females to SSLs and CRC. Our findings may have implications for the design of CRC screening programs.

Relationship between prediagnostic body mass index trajectory and colorectal adenomas: an analysis of the PLCO cancer screening trial

Background

Studies on the relationship between lifetime body mass index (BMI) trajectory and colorectal premalignant precursor lesions are limited. This study aimed to assess the relationship between prediagnostic adulthood BMI trajectory and the risk of colorectal adenomas using data from the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial.

Methods

In total, 39,824 participants in the intervention arm of the prospective PLCO cohort, who have undergone at least one colonoscopy or sigmoidoscopy examination with a confirmed diagnosis of colorectal adenomas, were enrolled and divided into four groups (underweight, normal weight, overweight, and obese) according to BMI during each age period. SAS Proc Traj was used to establish the BMI trajectory model. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

Compared with normal weight, overweight or obesity significantly increased colorectal adenomas risk in each age period after 30 years. Specifically, obesity in the 50s was most closely related to colorectal adenomas risk [HR: 1.32, 95% CI: (1.22, 1.43)]. BMI gain from the age of 40 to 50 [HR: 1.25, 95% CI: (1.11, 1.42)] showed the strongest correlation with an increased incidence of colorectal adenomas, followed by that from the age of 30 to 50 [HR: 1.19, 95% CI: (1.10, 1.29)], the age of 20 to 50 [HR: 1.16, 95% CI: (1.10, 1.24)], the age of 20 to 40 [HR: 1.14, 95% CI: (1.05, 1.23)], and the age of 20 to 30 [HR: 1.13, 95% CI: (1.02, 1.26)]. Additionally, compared with those who maintained normal weight throughout adulthood, those who progressed from normal weight to obesity [HR: 1.15, 95% CI: (1.06, 1.25)], or from overweight to obesity [HR: 1.33, 95% CI: (1.11, 1.61)], had a higher risk of colorectal adenomas.

Conclusions

Overweight and obesity increased the risk of colorectal adenomas, and this risk increased with advancing age.

The impact of body weight on dysplasia of colonic adenomas: a case-control study

OBJECTIVE

Colorectal cancer (CRC) is common across countries in males and females. Most cases originate from adenomas harboring high grade dysplasia. Among risk factors, weight excess has been suggested to positively influence dysplasia progression. In this study, the relationship between dysplasia grade of adenomas and body mass index (BMI) categories was analyzed.

METHODS

This was a retrospective case-control study. A total of 4745 charts (59.8% females) from patients undergoing colonoscopy were collected. Data regarding age, sex, smoking habits, occupation, residence, personal history of CRC, personal history of polyps and BMI were retrieved. Adenomas with high-grade dysplasia were labeled as advanced.

RESULTS

They were 970 (20.4%) subjects with adenomas (cases: mean age 64.67 ± 11.35 years) and 3775 without (controls: mean age 56.43 ± 16.56 years). As expected, adenomas were significantly associated with overweight or obesity. After adjusting for all covariates the presence of advanced adenoma was significantly associated with age, male sex, smoking habits, personal history of CRC, overweight (OR = 1.298, IC 95% 1.092-1.697) and obesity (OR = 1.780, IC 95% 1.260-2.515).

CONCLUSIONS

Our findings support the protective effect a normal weight against advanced adenomas. Reduction of BMI value should be pursued in healthy programs.

Predictors of inadequate bowel preparation for colonoscopy: a systematic review and meta-analysis

The aim of this study was to investigate factors contributing to poor bowel preparation in patients undergoing colonoscopy procedures. We used a reproducible search strategy to identify studies, searching 10 medical databases, including PubMed, Ovid, Medline, and Cochrane Library Database for reports published between 2000 and 2016. Fully published studies, evaluating risk factors for inadequate bowel preparation, were included. Two reviewers independently scored the identified studies for methodology and abstracted pertinent data. Pooling was conducted with both fixed-effects and random-effects models; results were presented from the random effects model when heterogeneity was significant. Odds ratios (OR) estimates with 95% confidence interval were calculated. Heterogeneity was assessed by I statistics. Twenty-four studies with a total of 49 868 patients met the inclusion criteria. Age (OR: -1.20), male sex (OR: 0.85), inpatient status (OR: 0.57), diabetes mellitus (OR: 0.58), hypertension (OR: 0.58), cirrhosis (OR: 0.49), narcotic use (OR: 0.59), constipation (OR: 0.61), stroke (OR; 0.51), and tricyclic antidepressant (TCA) use (0.51), were associated with inadequate bowel preparation. In our sensitivity analysis comparing Western and Asian countries, we found that diabetes, cirrhosis, male sex, history of stroke and TCA use were stronger risk factors for inadequate bowel preparation in Western countries than in Asian countries. We also found that history of stroke, TCA use, and race were risk factors for inadequate bowel preparation in patients receiving conventional bowel preparation compared with those receiving split-dose bowel preparation. Multiple risk factors affect the quality of bowel preparation and specific risk factors can be intervened upon, in different populations, to optimize preparation.

Association between investigator-measured body-mass index and colorectal adenoma: a systematic review and meta-analysis of 168,201 subjects

The objective of this meta-analysis is to evaluate the odds of colorectal adenoma (CRA) in colorectal cancer screening participants with different body mass index (BMI) levels, and examine if this association was different according to gender and ethnicity. The EMBASE and MEDLINE were searched to enroll high quality observational studies that examined the association between investigator-measured BMI and colonoscopy-diagnosed CRA. Data were independently extracted by two reviewers. A random-effects meta-analysis was conducted to estimate the summary odds ratio (SOR) for the association between BMI and CRA. The Cochran’s Q statistic and I² analyses were used to assess the heterogeneity. A total of 17 studies (168,201 subjects) were included. When compared with subjects having BMI < 25, individuals with BMI 25–30 had significantly higher risk of CRA (SOR 1.44, 95% CI 1.30–1.61; I² = 43.0%). Subjects with BMI ≥ 30 had similarly higher risk of CRA (SOR 1.42, 95% CI 1.24–1.63; I² = 18.5%). The heterogeneity was mild to moderate among studies. The associations were significantly higher than estimates by previous meta-analyses. There was no publication bias detected (Egger’s regression test, p = 0.584). Subgroup analysis showed that the magnitude of association was significantly higher in female than male subjects (SOR 1.43, 95% CI 1.30–1.58 vs. SOR 1.16, 95% CI 1.07–1.24; different among different ethnic groups (SOR 1.72, 1.44 and 0.88 in White, Asians and Africans, respectively) being insignificant in Africans; and no difference exists among different study designs. In summary, the risk conferred by BMI for CRA was significantly higher than that reported previously. These findings bear implications in CRA risk estimation.

Association Between Colorectal Cancer and Atherosclerotic Diseases: A Study Using a National Inpatient Database in Japan

BACKGROUND

Both colorectal neoplasms and atherosclerosis can be induced by common visceral fat accumulation. However, the association between these diseases at the advanced stage, colorectal cancer and cardiovascular/cerebrovascular diseases, has not been elucidated.

AIMS

This study aimed to investigate the association between colorectal cancer and vascular diseases in relation to obesity and metabolic disorders, using a nationwide database of hospitalized patients in Japan. We used non-cardiac gastric cancer patients as a reference, because they were considered to be neutral for obesity or metabolic disorders.

METHODS

We identified 54,591 patients with colorectal cancer and 19,565 patients with gastric cancer from the Diagnosis Procedure Combination database. The data collected included: sex; age; body mass index (BMI); smoking status; comorbidity; and medication data, comprising hypertension, diabetes, hyperlipidemia, coronary artery disease, and stroke. We compared these data in a cross-sectional setting by multivariate analyses.

RESULTS

Multivariate logistic regression analyses showed that female sex, increased BMI, hypertension [odds ratio (OR) 1.11; 95 % confidence interval (CI) 1.07-1.15; P < 0.0001], and diabetes (OR 1.17; 95 % CI 1.12-1.23; P < 0.0001) were more associated with colorectal cancer than with gastric cancer. Smoking, aspirin use (OR 0.85; 95 % CI 0.79-0.92; P < 0.0001), and coronary artery disease (OR 0.90; 95 % CI 0.86-0.95; P = 0.0001) were inversely associated with colorectal cancer.

CONCLUSIONS

Obesity and metabolic disorders were more associated with colorectal cancer than with non-cardiac gastric cancer, while coronary artery disease (CAD) was inversely associated. Some mechanisms involving separate populations of colorectal cancer and CAD under visceral fat accumulation might be suggested.

Pulse-wave velocity, the ankle-brachial index, and the visceral fat area are highly associated with colorectal adenoma

BACKGROUND

Although both colorectal neoplasms and atherosclerosis may be induced by visceral fat accumulation, no association between these factors has yet been elucidated.

METHODS

Among Japanese participants in our colonoscopic screening and annual surveillance programs, asymptomatic subjects were investigated. Visceral fat area was measured by computed tomography, and the ankle-brachial index and pulse-wave velocity (markers of systemic atherosclerosis) were also estimated. Colorectal findings during screening were investigated in association with these parameters.

RESULTS

Nine hundred and seven subjects (males: 71.9%; mean age: 57.3±8.7 years) were enrolled. Colorectal adenomas were identified during colorectal screening of 407 subjects (44.9%). The prevalence of all colorectal adenoma and advanced neoplasia increased with an elevated pulse-wave velocity from 32.2% (advanced neoplasia, 2.6) to 62.1% (8.4%) in higher quartiles (p<0.001 and p=0.003). The risk of advanced neoplasia was higher in subjects with an abnormal ankle-brachial index (33% vs. 4.6%, p<0.001). Upon multivariate analysis, visceral fat area and pulse-wave velocity were associated with all adenoma, and the ankle-brachial index with advanced neoplasia.

CONCLUSIONS

The risk of colorectal adenoma was strongly associated with visceral fat area and markers of atherosclerosis. Colorectal adenoma and atherosclerosis may share a common pathogenesis and the same populations are at high-risk.

Obesity, metabolic factors, and colorectal adenomas: a retrospective study in a racially diverse New York State Hospital

OBJECTIVE

We studied a racially diverse population and the relationship with colorectal adenomas (CA) further looking for risks related to BMI and metabolic factors.

DESIGNS

Seven hundred seventy-nine patients who underwent screening colonoscopies between 2007 and 2009 meeting exclusion criteria were included. To evaluate the association between race, BMI, and other metabolic factors with having one or more CA detected at colonoscopy, adjusted odds ratios and 95 % CI were estimated using unconditional logistic regression models.

OUTCOMES

CA were detected in 167 out of 779 (21.4 %) patients. Compared to Whites, Hispanics were less likely to have one or more adenomas detected during a screening colonoscopy (OR = 0.52, 95 % CI, 0.31-0.88; p = 0.01). There was no significant statistical difference between Blacks and Whites, or other races and Whites. There was an association between the presence of CA and smoking (OR = 1.57, 95 % CI, 1.02-2.43; p = 0.04).

CONCLUSION

Our results showed that Hispanics were less likely to have an adenoma detected during a screening colonoscopy than Whites. No statistical significant difference was found between patients with metabolic factors and the presence of colorectal adenoma.

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.

Colorectal cancer screening in an equal access healthcare system

INTRODUCTION

The military health system (MHS) a unique setting to analyze implementation programs as well as outcomes for colorectal cancer (CRC). Here we look at the efficacy of different CRC screening methods, attributes and results within the MHS, and current barriers to increase compliance.

MATERIALS AND METHODS

A literature search was conducted utilizing PubMed and the Cochrane library. Key-word combinations included colorectal cancer screening, racial disparity, risk factors, colorectal cancer, screening modalities, and randomized control trials. Directed searches were also performed of embedded references.

RESULTS

Despite screening guidelines from several national organizations, extensive barriers to widespread screening remain, especially for minority populations. These barriers are diverse, ranging from education and access problems to personal beliefs. Screening rates in MHS have been reported to be generally higher at 71% compared to national averages of 50-65%.

CONCLUSION

CRC screening can be highly effective at improving detection of both pre-malignant and early cancers. Improved patient education and directed efforts are needed to improve CRC screening both nationally and within the MHS.

The association between obesity and colorectal adenoma: systematic review and meta-analysis

OBJECTIVE

Obesity (body mass index [BMI] ≥30) or overweight (25 ≤ BMI ≤29.9) has been reported to be a risk factor for colorectal adenoma (CRA). However, this association remains controversial. The aim of this study was to determine the association between overweight or obesity and CRA.

DESIGN

Systematic review and meta-analysis were conducted using English language studies from EMBASE and MEDLINE. Appropriate observational studies were selected from 1966 through September 2011. Adjusted odds ratios (ORs) were extracted from each study.

RESULTS

One hundred and seventy full-text articles were reviewed after retrieving 1199 initial search results. Five studies in which BMI was treated as continuous variable, three studies in which BMI was dichotomized using a cutoff value of 25, three studies in which BMI was categorized into three groups using values of 22 and 25, and eight studies in which BMI was categorized into three groups using values of 25 and 30 were selected. Regarding risk for CRA, pooled OR [95% CI] of one increment increase in BMI was 1.02 [0.99-1.03] (random effects model [REM]), while that of BMI ≥ 25 was 1.27 [1.15-1.4] (Fixed effects model). Pooled ORs [95% CI] of BMI ≥ 22 and BMI ≥ 25 was 1.42 [0.69-2.9] [REM] and 1.81 [0.36-9.1] [REM], respectively. Pooled ORs [95% CI] of BMI ≥ 25 and BMI ≥ 30 was 1.16 [0.98-1.38] [REM] and 1.47 [1.18-1.83] [REM], respectively.

CONCLUSION

Obesity and overweight are significant risk factors for CRA. However, there are no data showing linear relationship between increasing BMI and CRA.

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.

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.

Detection of colorectal neoplasia by colonoscopy in average-risk patients age 40-49 versus 50-59 years

BACKGROUND

The USPSTF recommends beginning colorectal cancer screening at age 50. A recent study showed prevalence of colorectal adenomas among individuals aged 40-49 was similar to that among those aged 50-59.

AIM

To assess the prevalence of colorectal neoplasia, detected during colonoscopy, by age among average-risk patients.

METHODS

Nine-hundred and ninety-four colonoscopies were analyzed (247 ages 40-49, 747 ages 50-59). We included consecutive patients of ages 40-59 undergoing their first colonoscopy. Colonoscopies that did not reach the cecum and patients at increased risk of colorectal cancer were excluded. The primary endpoint was the prevalence of colorectal neoplasia by age. Secondary endpoints included the prevalence of colorectal neoplasia by gender, ethnicity, and BMI.

RESULTS

The prevalence of colorectal neoplasia was 12.1% in patients aged 40-49 and 22.6% in those aged 50-59. Compared with individuals aged 40-49 there was a significantly greater prevalence of adenomas (chi-squared = 12.72, P = 0.0004) and of advanced adenomas or cancer (chi-squared = 5.73, P = 0.01) in individuals aged 50-59. After adjusting for gender, race, and BMI the effect of age remained significant (OR 0.5, 95% CI 0.33-0.76). Higher BMI was associated with increased risk of colorectal neoplasia (OR 1.03, 95% CI 1.00-1.06). The number that had to be screened to detect one advanced lesion in the 40-49 age group was 49 compared with 20 in those aged 50-59.

CONCLUSION

Individuals aged 40-49 have a lower but measurable risk of colorectal neoplasia compared with those aged 50-59. Although there may be population subgroups for which screening below the age of 50 may be indicated, our results do not support lowering the age threshold for colonoscopy in the general population.

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.

Anthropometric factors in adulthood and risk of colorectal adenomas: The French E3N-EPIC prospective cohort

Anthropometric factors have been associated with colorectal cancer and adenomas but with conflicting results in women or regarding adenoma characteristics. The authors aimed to explore associations between anthropometric factors (height, weight, body mass index, waist and hip circumferences, and weight changes) and adenoma risk. They analyzed the 17,391 women of the French Etude épidémiologique des femmes de la Mutuelle Générale de l'Education Nationale (E3N)-European Prospective Investigation into Cancer and Nutrition (EPIC) cohort who underwent a colonoscopy during follow-up (1993-2002), including 1,408 who developed a first colorectal adenoma. In Cox multivariate proportional hazard regression models, obesity was associated with an increased colorectal adenoma risk (hazard ratio = 1.53, 95% confidence interval: 1.21, 1.94). This association was restricted to left colon adenomas (P(homogeneity) = 0.05 and 0.01 for colon vs. rectum and right vs. left colon, respectively), with a dose-effect relation observed from 22 kg/m². A high waist circumference was also associated with left colon adenoma risk (hazard ratio = 1.81, 95% confidence interval: 1.36, 2.41). Mean weight gain over 0.5 kg/year was associated with a 23% increased colorectal adenoma risk. Associations did not differ between advanced and nonadvanced adenomas. In conclusion, study findings suggest that obesity and weight gain are associated with early colorectal carcinogenesis in women, and specifically regarding the distal colon.

Impact of lifestyle factors on colorectal polyp detection in the screening setting

BACKGROUND

Awareness of risk factors for colorectal neoplasia could address risk reduction strategies in asymptomatic subjects.

METHODS

This is a post hoc analysis of a prospective, cross-sectional study of 1321 asymptomatic adults. All the subjects underwent same-day CT colonography and colonoscopy to determine the prevalence of colorectal neoplasia. The variables examined included body mass index, smoking, alcohol consumption, age, and gender. Univariate and logistic regression analyses were performed for detection of colorectal neoplasia and hyperplastic polyps. Odds ratios with 95% confidence intervals were calculated.

RESULTS

Colorectal adenomas and hyperplastic polyps were detected in 378 (28.6%) and 157 (11.9%) participants, respectively. In both univariate and multivariate analysis, increasing age, male gender, and body mass index > or =25 were significantly associated with the detection of colorectal adenomas, with an odds ratio of 1.22 (95% CI,1.09-1.36), 1.28 (95% CI, 1.06-1.45), and 1.34 (95% CI, 1.02-1.77), respectively. A history of smoking was the only identifiable risk factor for hyperplastic polyps (odds ratio, 1.98; 95% CI, 1.41-2.78).

CONCLUSIONS

Body mass index > or =25, increasing age, and male gender were all associated with an increased likelihood of colorectal adenomas at screening, whereas smoking was strongly associated with hyperplastic polyps.

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.

Does level of sedation impact detection of advanced neoplasia?

BACKGROUND AND AIMS

Two of the foremost issues in screening colonoscopy involve delivering quality and maximizing adenoma detection rates (ADR). Little is known about the impact of deep sedation on ADR. This study aims to compare the detection of advanced lesions during screening colonoscopy performed with moderate conscious sedation (MCS) versus deep sedation (DS).

METHODS

A retrospective cohort study was performed using the Clinical Outcomes Research Initiative database. Average risk screening colonoscopies performed January 2000 to December 2005 were examined for practice setting, patient demographics, and findings, including detection of a polyp >9 mm and suspected malignant lesions.

RESULTS

A total of 104,868 colonoscopies were examined, 97% of which were performed with MCS. Univariate analysis demonstrated that more polyps of any size were detected with MCS (38 vs. 34%, p < 0.0001) and more advanced lesions were found with DS compared with MCS (7 vs. 6%, p = 0.01). When exclusively examining sites that performed DS > 10% for all procedures, a more significant increase in advanced lesion detection when using DS was observed (7.5 vs. 5.7%, p = 0.003). When adjusted for age, gender, race/ethnicity, site, prep quality, and ASA group, DS was 25% more likely to detect an advanced lesion.

CONCLUSIONS

Our data suggest that use of DS may be associated with a higher rate of advanced lesion detection. However, this retrospective design has limitations that necessitate follow-up with prospective studies. These follow-up studies would be essential to support any change in the standard practices of sedation.

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.

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.

Impact of obesity on bowel preparation for colonoscopy

BACKGROUND & AIMS

An inadequately cleansed colon can lead to missed lesions, repeat procedures, increased cost, and complications from colonoscopy. Because obesity, with its known link to colorectal neoplasia, might be associated with inadequate bowel cleansing, we investigated the impact of increased body mass index (BMI) on quality of bowel preparation at colonoscopy.

METHODS

All colonoscopy procedures performed at a tertiary referral center during a 4-month period were evaluated. Bowel preparation was assigned a unique composite outcome score that took into account a subjective bowel preparation score, earlier recommendation for follow-up colonoscopy as a result of inadequate bowel preparation, and the endoscopist's confidence in adequate evaluation of the colon. Univariate and multivariate logistic regression analyses were performed to identify the role of BMI in predicting an inadequate bowel preparation.

RESULTS

During the study period, 1588 patients (59.1% female; mean age, 57.4 +/- 0.34 years) fulfilled inclusion criteria. An abnormal BMI (> or =25) was associated with an inadequate composite outcome score (P = .002). In multivariate logistic regression analyses, both BMI > or =25 (P = .04) and > or =30 (P = .006) were retained as independent predictors of inadequate bowel preparation. Each unit increase in BMI increased the likelihood of an inadequate composite outcome score by 2.1%. Additional independent predictors of inadequate preparation exponentially increased the likelihood of an inadequate composite outcome score; 7 additional risk factors identified 97.5% of overweight patients with an inadequate composite outcome score.

CONCLUSIONS

Obesity is an independent predictor of inadequate bowel preparation at colonoscopy. The presence of additional risk factors further increases the likelihood of a poorly cleansed colon.

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.

Components of metabolic syndrome and metachronous colorectal neoplasia

BACKGROUND

The consistent association between obesity and colorectal cancer is thought to be explained by metabolic disturbances common, but not exclusive, to the obese.

METHODS

We assessed the relation between metachronous neoplasia and the components of metabolic syndrome (MetS) as defined by the National Cholesterol Education Program's Adult Treatment Panel III in 2,392 participants of two previously conducted chemoprevention trials. Waist circumference, fasting plasma glucose, trigylcerides, high-density lipoprotein, and systolic and diastolic blood pressure were measured at baseline.

RESULTS

MetS classification was associated with increased odds of metachronous neoplasia among women [odds ratio (OR), 1.37; 95% confidence interval (95% CI), 1.01-1.85] but not among men (OR, 0.99; 95% CI, 0.81-1.21). High waist circumference in men (OR, 1.41; 95% CI, 1.15-1.72) and women (OR, 1.41; 95% CI, 1.05-1.90) and elevated fasting glucose in women (OR, 1.46; 95% CI, 1.09-1.96), as defined by Adult Treatment Panel III cutpoints, were associated with increased odds, whereas none of the other criteria were independently associated with metachronous neoplasia. When each trait was evaluated using quartiles, elevated glucose among women and large waist circumference among men were significantly associated with metachronous lesions. Exploratory analysis of waist circumference and fasting glucose suggested an interaction, where only the combination of large waist circumference and elevated glucose conferred significant increased odds of metachronous neoplasia among both men (OR, 1.36; 95% CI, 1.04-1.78; P(interaction) = 0.08) and women (OR, 1.83; 95% CI, 1.26-2.67; P(interaction) = 0.12).

CONCLUSIONS

These results suggest that, of the specific components of MetS, those that capture impaired glucose uptake increased the odds of metachronous neoplasia.

Association between body mass index and colorectal neoplasia at follow-up colonoscopy: a pooling study

A direct relation between body mass index (BMI) and risk of colorectal adenomas and cancer has been reported, but few studies have had adequate sample size for conducting stratified analyses by sex, family history, colorectal subsite, or features of metachronous lesions. Data from 8,213 participants in 7 prospective studies of metachronous colorectal adenomas were pooled to assess whether the association between BMI and metachronous neoplasia varied by these factors. A statistically significant direct association between BMI and the odds of nonadvanced adenomas (P(trend) < 0.001) was observed, while the relation for advanced adenomas was of marginal significance (P(trend) < 0.07). In sex-stratified analyses, obesity was statistically significantly associated with the odds of any metachronous lesion among men (odds ratio = 1.36, 95% confidence interval: 1.17, 1.58) but not among women (odds ratio = 1.10, 95% confidence interval: 0.89, 1.37). The associations with BMI appeared to be limited to proximal neoplasia, with statistically significant results for BMI and proximal (P(trend) < 0.001), but not distal (P(trend) < 0.85), neoplasia. Exploratory analyses indicated that BMI was significantly related to most histologic characteristics of metachronous adenomas among men but not among women. Our results provide further support for the association between BMI and metachronous colorectal adenomas, particularly among men, thereby indicating that body size may affect colorectal carcinogenesis at comparatively early stages.

American College of Gastroenterology guidelines for colorectal cancer screening 2009 [corrected]

This document is the first update of the American College of Gastroenterology (ACG) colorectal cancer (CRC) screening recommendations since 2000. The CRC screening tests are now grouped into cancer prevention tests and cancer detection tests. Colonoscopy every 10 years, beginning at age 50, remains the preferred CRC screening strategy. It is recognized that colonoscopy is not available in every clinical setting because of economic limitations. It is also realized that not all eligible persons are willing to undergo colonoscopy for screening purposes. In these cases, patients should be offered an alternative CRC prevention test (flexible sigmoidoscopy every 5-10 years, or a computed tomography (CT) colonography every 5 years) or a cancer detection test (fecal immunochemical test for blood, FIT).

Lifestyle, genes, and cancer

It is estimated that almost 1.5 million people in the USA are diagnosed with cancer every year. However, due to the substantial effect of modifiable lifestyle factors on the most prevalent cancers, it has been estimated that 50% of cancer is preventable. Physical activity, weight loss, and a reduction in alcohol use can strongly be recommended for the reduction of breast cancer risk. Similarly, weight loss, physical activity, and cessation of tobacco use are important behavior changes to reduce colorectal cancer risk, along with the potential benefit for the reduction of red meat consumption and the increase in folic acid intake. Smoking cessation is still the most important prevention intervention for reducing lung cancer risk, but recent evidence indicates that increasing physical activity may also be an important prevention intervention for this disease. The potential benefit of lifestyle change to reduce prostate cancer risk is growing, with recent evidence indicating the importance of a diet rich in tomato-based foods and weight loss. Also, in the cancers for which there are established lifestyle risk factors, such as physical inactivity for breast cancer and obesity for colorectal cancer, there is emerging information on the role that genetics plays in interacting with these factors, as well as the interaction of combinations of lifestyle factors. Integration of genetic information into lifestyle factors can help to clarify the causal relationships between lifestyle and genetic factors and assist in better identifying cancer risk, ultimately leading to better-informed choices about effective methods to enhance health and prevent cancer.

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.

The effect of body weight reduction on the incidence of colorectal adenoma

OBJECTIVES

Obesity is thought to be associated with colorectal cancer and adenoma. We aimed to investigate the effect of body weight on the risk of colorectal adenoma both in cross-sectional and longitudinal analyses.

METHODS

This is a retrospective cohort study in a large-scale health appraisal institution in Japan. A total of 7,963 asymptomatic, average-risk Japanese were enrolled at initial examinations, and 2,568 subjects who underwent a second colonoscopy after 1 yr were investigated. The association with the prevalence of colorectal adenoma was evaluated according to the body mass index (BMI) at the initial examination. The incidence of colorectal adenoma at the second colonoscopy was investigated according to the initial BMI and body weight changes during the year.

RESULTS

The prevalence of colorectal adenoma increased in relation to increases in the BMI: 15.4%, 20.6%, 22.7%, and 24.2%, respectively, in the first (BMI < 21.350), second (21.350 < or = BMI < 23.199), third (23.199 < or = BMI < 25.156), and fourth (25.156 < or = BMI) quartiles. The adjusted odds ratios in reference to Group Q1 were 1.15 (95% CI 0.97-1.37, P= 0.1) for Group Q2, 1.19 (1.01-1.41, P= 0.04) for Group Q3, and 1.32 (1.12-1.56, P= 0.001) for Group Q4. The incidence rates of colorectal adenoma after 1 yr also increased proportionally according to the initial BMI: Group Q1 (12.9%), Group Q2 (15.7%), Group Q3 (18.3%), and Group Q4 (19.0%).

CONCLUSIONS

Obesity was associated with the risk for colorectal adenoma, and body weight reduction was suggested to decrease this risk.

Anthropometric risk factors for colorectal polyps in African-American women

OBJECTIVE

Colorectal adenomas are thought to be precursor lesions to colorectal cancer, a leading cause of cancer incidence and mortality in African-American women. Studies suggest that obesity is associated with risk of adenomas in white women, but little is known about the relation in African-American women. We prospectively examined the association between selected anthropometric factors and colorectal polyps in African-American women.

METHODS AND PROCEDURES

Data were obtained from the Black Women's Health Study (BWHS), a prospective cohort study of African-American women. From 1997 to 2003, we followed 33,403 women aged > or =30 years with no prior diagnosis of cancer or polyps. Cox regression was used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for risk of polyps, with adjustment for potential confounders.

RESULTS

After 211,797 person-years of follow-up, 1,189 cases of colorectal polyps were reported. The IRR comparing women with a current BMI > or =35 to <25 kg/m(2) was 1.35 (95% CI = 1.12-1.62), after adjustment for covariates including waist-to-hip ratio (WHR). Women who gained > or =30 kg since age 18 were 1.76 times as likely as those who gained <5 kg to report polyps (95% CI = 1.33-2.33). The IRR comparing the highest (>or =0.87) to lowest (<0.71) quintiles of WHR was 1.26 (95% CI = 1.04-1.54), after adjustment for covariates including BMI. BMI at age 18, adult height, and waist circumference (BMI-adjusted) were not materially associated with risk. Results were similar among women with a recent endoscopy.

DISCUSSION

Weight gain and obesity in adulthood may increase the risk of colorectal polyps in African-American women.

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.

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.

An association between obesity and the prevalence of colonic adenoma according to age and gender

BACKGROUND

Epidemiologic data on obesity as a risk factor for colonic adenoma with respect to gender have not yet been confirmed. Here, we aimed to compare the prevalence of colonic adenoma and of advanced polyps in age-stratified men and women at baseline, to examine the role of body mass index (BMI) on colonic adenoma risk according to age and gender, and to examine the influence of menopausal status.

METHODS

A total of 1744 asymptomatic patients (946 men, 798 women) who underwent colonoscopy for cancer screening at Ewha Mokdong Hospital, Seoul, Korea, between February and June 2005, were eligible. BMI was assessed, and histology, size, and location of the adenoma were examined for each patient. Women were interviewed for menopausal status and a history of hormone replacement therapy.

RESULTS

A significant increase in the prevalence of colonic adenoma and of advanced polyps was found to occur with age (P for trend < 0.01). The prevalences of adenoma and advanced polyps were higher in men in most age groups (P < 0.01), but no significant difference in prevalences was observed between genderes in patients 70 years of age or older. Moreover, a positive association between BMI and the prevalence of colonic adenoma and advanced polyps was shown in relatively young individuals of both gender (men in their thirties, P < 0.05; women in their forties, P < 0.05), and premenopausal women according to hormonal status (P = 0.01).

CONCLUSIONS

Our data suggest that obesity increases the risk of colonic adenoma in relatively young people and in premenopausal women subject to estrogen effects.

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.

Do Factors Related to Endogenous and Exogenous Estrogens Modify the Relationship between Obesity and Risk of Colorectal Adenomas in Women?

Obesity has consistently been associated with increased colorectal cancer risk in men, but not in women. In the absence of postmenopausal hormone use (PMH), adipose-derived estrogen is the primary determinant of circulating estrogen levels in postmenopausal women, perhaps ameliorating the mitogenic effects of obesity in this group. Using data from a case-control study in the United States, we examined associations among obesity, potential modifying effects of factors related to endogenous and exogenous estrogen levels, and risk of colorectal adenoma. Cases (n = 219) were women of ages 30 to 74 years with colonoscopy proven, incident, sporadic, pathology-confirmed, adenomatous polyps of the colon and rectum. Two control groups were recruited: colonoscopy-confirmed polyp-free women (n = 438) and age- and zip code frequency-matched women randomly selected from the community (n = 247). Multivariate odds ratios and 95% confidence intervals (95% CI) for obese [body mass index (BMI) >or=30.0; compared with nonobese, BMI <25.0] premenopausal women were 2.09 (95% CI, 0.81-5.41) versus colonoscopy controls, and 5.18 (95% CI, 1.40-19.32) versus population controls. For PMH users, the corresponding odds ratios were 0.29 (95% CI, 0.12-0.70) versus colonoscopy controls and 0.64 (95% CI, 0.23-1.83) versus population controls. There was no significant association of BMI with adenoma risk for PMH nonusers. Findings for waist-to-hip ratio were similar to those for BMI. These data support the hypothesis that risk for colorectal adenoma may be increased with obesity among premenopausal women but decreased among postmenopausal women, especially if they also take PMH.

A Follow-up Study of Physical Activity and Incidence of Colorectal Polyps in African-American Women

BACKGROUND

Physical activity is associated with a reduced risk of colon cancer, but the effect of activity on colorectal adenomas, which are precursors to colon cancer, is uncertain. The influence of physical activity on colorectal adenomas among African-American women is of particular interest because African-American women have an increased risk of colon cancer relative to other U.S. women.

METHODS

We prospectively assessed the relation of physical activity to the incidence of colorectal polyps among African-American women. We followed 45,400 women in the Black Women's Health Study from 1997 to 2003. Data were obtained by biennial mailed questionnaires. During 287,029 person-years of follow-up, 1,390 women reported having been diagnosed with colorectal polyps. A review of medical records of 58 women who reported colorectal polyps indicated that 59% had adenomas and 41% had hyperplastic polyps. We converted hours per week of vigorous exercise and hours per week of walking to metabolic equivalent (MET)-hours. We estimated incidence rate ratios with Cox proportional hazard models, controlling for age, body mass index, smoking, family history of colorectal cancer, and education.

RESULTS

For total MET-hours/wk spent in walking and vigorous exercise, the incidence rate ratio decreased from 0.94 for <5 MET-hours/wk to 0.72 for >or=40 MET-hours/wk (P(trend) = 0.01). The inverse association was apparent among most subgroups examined, including women who may be at higher risk of colorectal adenomas because of being obese.

CONCLUSIONS

Increased physical activity is associated with a reduced incidence of colorectal polyps among African-American women.

Body mass index, body height, and subsequent risk of colorectal cancer in middle-aged and elderly Japanese men and women: Japan public health center-based prospective study

OBJECTIVE

To investigate the association of body mass index (BMI) or body height with colorectal cancer incidence in a population-based prospective study.

METHODS

We identified 986 (626 men and 360 women) newly diagnosed cases of colorectal cancer during the 9.4-year follow-up of a cohort consisting of 102,949 (49,158 male and 53,791 female) middle-aged and elderly Japanese.

RESULTS

Lower BMI groups (lower than 23) were not associated with colorectal cancer compared with the 23-24.9 BMI group. Any categories of 25-26.9, 27-29.9, or 30 or more BMI were associated with an increased risk of colorectal cancer compared with the lower than 25 BMI (RR, 1.2 for 25-26.9, 1.4 for 27-29.9, and 1.5 for 30 or more; p for trend, 0.004) in men. These associations were more evident only in invasive-type cancer analysis. BMI was not associated with the risk of colorectal cancer in women. No significant association with height was obtained for either men or women.

CONCLUSIONS

The association of BMI with colorectal cancer was confirmed in a Japanese population as well as Western populations. Only invasive-cancer analysis suggested that BMI was important for tumor growth and proliferation. Approximately 6.7% of colorectal cancer was attributable to a BMI of 25 or higher in middle-aged and elderly Japanese men.

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.

Obesity and colorectal cancer: epidemiology, mechanisms and candidate genes

There is increasing evidence that dysregulation of energy homeostasis is associated with colorectal carcinogenesis. Epidemiological data have consistently demonstrated a positive relation between increased body size and colorectal malignancy, whereas mechanistic studies have sought to uncover obesity-related carcinogenic pathways. The phenomenon of "insulin resistance" or the impaired ability to normalize plasma glucose levels has formed the core of these pathways, but other mechanisms have also been advanced. Obesity-induced insulin resistance leads to elevated levels of plasma insulin, glucose and fatty acids. Exposure of the colonocyte to heightened concentrations of insulin may induce a mitogenic effect within these cells, whereas exposure to glucose and fatty acids may induce metabolic perturbations, alterations in cell signaling pathways and oxidative stress. The importance of chronic inflammation in the pathogenesis of obesity has recently been highlighted and may represent an additional mechanism linking increased adiposity to colorectal carcinogenesis. This review provides an overview of the epidemiology of body size and colorectal neoplasia and outlines current knowledge of putative mechanisms advanced to explain this relation. Family based studies have shown that the propensity to become obese is heritable, but this is only manifest in conditions of excess energy intake over expenditure. Inheritance of a genetic profile that predisposes to increased body size may also be predictive of colorectal cancer. Genomewide scans, linkage studies and candidate gene investigations have highlighted more than 400 chromosomal regions that may harbor variants that predispose to increased body size. The genetics underlying the pathogenesis of obesity are likely to be complex, but variants in a range of different genes have already been associated with increased body size and insulin resistance. These include genes encoding elements of insulin signaling, adipocyte metabolism and differentiation, and regulation of energy expenditure. A number of investigators have begun to study genetic variants within these pathways in relation to colorectal neoplasia, but at present data remain limited to a handful of studies. These pathways will be discussed with particular reference to genetic polymorphisms that have been associated with obesity and insulin resistance.

Obesity and disease of the esophagus and colon

This article discusses the evidence linking obesity to the different manifestations of gastroesophageal reflux disease and colorectal cancer.

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.

Use of colonoscopy as a primary screening test for colorectal cancer in average risk people

OBJECTIVE

The use of colonoscopy as a primary screening test for colorectal cancer (CRC) in average risk adults is a subject of controversy. Our primary objective was to build a predictive model based on a few simple variables that could be used as a guide for identifying average risk adults more suitable for examination with colonoscopy as a primary screening test.

METHODS

The prevalence of advanced adenomas was assessed by primary screening colonoscopy in 2210 consecutive adults at least 40 yr old, without known risk factors for CRC. Age, gender, and clinical and biochemical data were compared among people without adenomas, those with non-advanced adenomas, and those with any advanced neoplasm. A combined score to assess the risk of advanced adenomas was built with the variables selected by multiple logistic regression analysis.

RESULTS

Neoplastic lesions were found in 617 subjects (27.9%), including 259 with at least one neoplasm that was 10 mm or larger, villous, or with moderate-to-severe dysplasia, and 11 with invasive cancers. Advanced lesions were more frequent among men, older people, and those with a higher body mass index (BMI). These three variables were independent predictors of advanced adenomas in multivariate analysis. A score combining age, sex, and BMI was developed as a guide for identifying individuals more suitable for screening colonoscopy.

CONCLUSIONS

Age, gender, and BMI can be used to build a simple score to select those average risk adults who might be candidates for primary screening colonoscopy.

Tobacco, alcohol, and p53 overexpression in early colorectal neoplasia

Background

The p53 tumor suppressor gene is commonly mutated in colorectal cancer. While the effect of p53 mutations on colorectal cancer prognosis has been heavily studied, less is known about how epidemiologic risk factors relate to p53 status, particularly in early colorectal neoplasia prior to clinically invasive colorectal cancer (including adenomas, carcinoma in situ (CIS), and intramucosal carcinoma).

Methods

We examined p53 status, as measured by protein overexpression, in 157 cases with early colorectal neoplasia selected from three New York City colonoscopy clinics. After collecting paraffin-embedded tissue blocks, immunohistochemistry was performed using an anti-p53 monoclonal mouse IgG₂a [BP53-12-1] antibody. We analyzed whether p53 status was different for risk factors for colorectal neoplasia relative to a polyp-free control group (n = 508).

Results

p53 overexpression was found in 10.3%, 21.7%, and 34.9%, of adenomatous polyps, CIS, and intramucosal cases, respectively. Over 90% of the tumors with p53 overexpression were located in the distal colon and rectum. Heavy cigarette smoking (30+ years) was associated with cases not overexpressing p53 (OR = 1.8, 95% CI = 1.1–2.9) but not with those cases overexpressing p53 (OR = 1.0, 95% CI = 0.4–2.6). Heavy beer consumption (8+ bottles per week) was associated with cases overexpressing p53 (OR = 4.0, 95% CI = 1.3–12.0) but not with cases without p53 overexpression (OR = 1.6, 95% CI = 0.7–3.7).

Conclusion

Our findings that p53 overexpression in early colorectal neoplasia may be positively associated with alcohol intake and inversely associated with cigarette smoking are consistent with those of several studies of p53 expression and invasive cancer, and suggest that there may be relationships of smoking and alcohol with p53 early in the adenoma to carcinoma sequence.