Obesity, weight change, and risk of adenoma recurrence: a prospective trial

Gastrointestinal: Weight gain increases the risk of metachronous advanced colorectal neoplasm observed in post-polypectomy surveillance colonoscopy

BACKGROUND AND AIM

Although obesity is a known risk factor for colorectal neoplasms, the correlation between weight change and colorectal neoplasm is unclear. Thus, we aim to evaluate the association between weight change and advanced colorectal neoplasm (ACRN) recurrence during post-polypectomy surveillance colonoscopy.

METHODS

This retrospective cohort study included 7473 participants diagnosed with colorectal neoplasms between 2003 and 2010 who subsequently underwent surveillance colonoscopies until 2020. We analyzed the association between the risk of metachronous ACRN and weight change, defining stable weight as a weight change of <3% and weight gain as a weight increase of ≥3% from baseline during the follow-up period.

RESULTS

During a median 8.5 years of follow-up, 619 participants (8.3%) developed ACRN. Weight gain was reported as an independent risk factor for metachronous ACRN in a time-dependent Cox analysis. A weight gain of 3-6% and ≥6% had adjusted hazard ratios (AHRs) of 1.48 (95% confidence interval [CI]: 1.19-1.84) and 2.14 (95% CI: 1.71-2.69), respectively. Participants aged 30-49 and 50-75 years with weight gain of ≥6% showed AHRs of 2.88 (95% CI: 1.96-4.21) and 1.90 (95% CI: 1.43-2.51), respectively. In men and women, weight gain of ≥3% was significantly correlated with metachronous ACRN.

CONCLUSIONS

Weight gain is associated with an increased risk of metachronous ACRN. Furthermore, weight gain is associated with the recurrence of ACRN in both men and women regardless of age.

The impact of surgical weight loss procedures on the risk of metachronous colorectal neoplasia: the differential effect of surgery type, sex, and anatomic location

Patients with prior colorectal polyps are at high risk for metachronous colorectal neoplasia, especially in the presence of obesity. We assessed the impact of 2 common bariatric surgeries, vertical sleeve gastrectomy and roux-n-Y gastric bypass, on the risk of colorectal neoplasia recurrence. This nationally representative analysis included 1183 postbariatric adults and 3193 propensity score-matched controls, who all had prior colonoscopy with polyps and polypectomy. Colorectal polyps reoccurred in 63.8% of bariatric surgery patients and 71.7% of controls at a mean follow-up of 53.1 months from prior colonoscopy. There was a reduced odds of colorectal polyp recurrence after bariatric surgery compared with controls (odds ratio [OR] = 0.70, 95% confidence interval [CI] = 0.58 to 0.83). This effect was most pronounced in men (OR = 0.58, 95% CI = 0.42 to 0.79), and post roux-n-Y gastric bypass (OR = 0.57, 95% CI = 0.41 to 0.79). However, the risk of rectal polyps or colorectal cancer remained consistent between groups. This study is the first to our knowledge to show a reduction in risk of polyp recurrence following bariatric surgery.

Beyond colonoscopy: Physical activity as a viable adjunct to prevent colorectal cancer

Colorectal cancer (CRC) is a common cancer with an increasing incidence worldwide. The implementation of a mass screening program has been proven effective in reducing the global burden of CRC, but its effectiveness is not ideal and some metabolic derangements and lifestyle factors were reported to be attributable for such a deficit. Implementing positive lifestyle intervention as primary prevention therefore becomes critical because colorectal carcinogenesis can be promoted by several lifestyle factors, such as a lack of physical activity. Herein, we review the current evidence on the association and possible mechanisms between physical activity and CRC carcinogenesis. In addition, since CRC prevention heavily relies on resection of precancerous polyps and subsequent surveillance by colonoscopy, this review will also explore the impact of physical activity on populations with different colorectal polyp risks and its potential adjunct role in altering surveillance outcomes.

Weight Loss and/or Sulindac Mitigate Obesity-associated Transcriptome, Microbiome, and Protumor Effects in a Murine Model of Colon Cancer

Obesity is associated with an increased risk of colon cancer. Our current study examines whether weight loss and/or treatment with the NSAID sulindac suppresses the protumor effects of obesity in a mouse model of colon cancer. Azoxymethane-treated male FVB/N mice were fed a low-fat diet (LFD) or high-fat diet (HFD) for 15 weeks, then HFD mice were randomized to remain on HFD (obese) or switch to LFD [formerly obese (FOb-LFD)]. Within the control (LFD), obese, and FOb-LFD groups, half the mice started sulindac treatment (140 ppm in the diet). All mice were euthanized 7 weeks later. FOb-LFD mice had intermediate body weight levels, lower than obese but higher than control (P < 0.05). Sulindac did not affect body weight. Obese mice had greater tumor multiplicity and burden than all other groups (P < 0.05). Transcriptomic profiling indicated that weight loss and sulindac each modulate the expression of tumor genes related to invasion and may promote a more antitumor immune landscape. Furthermore, the fecal microbes Coprobacillus, Prevotella, and Akkermansia muciniphila were positively correlated with tumor multiplicity and reduced by sulindac in obese mice. Coprobacillus abundance was also decreased in FOb-LFD mice. In sum, weight loss and sulindac treatment, alone and in combination, reversed the effects of chronic obesity on colon tumor multiplicity and burden. Our findings suggest that an investigation regarding the effects of NSAID treatment on colon cancer risk and/or progression in obese individuals is warranted, particularly for those unable to achieve moderate weight loss.

PREVENTION RELEVANCE

Obesity is a colon cancer risk and/or progression factor, but the underlying mechanisms are incompletely understood. Herein we demonstrate that obesity enhances murine colon carcinogenesis and expression of numerous tumoral procancer and immunosuppressive pathways. Moreover, we establish that weight loss via LFD and/or the NSAID sulindac mitigate procancer effects of obesity.

Active exercise after polypectomy reduces the risk of metachronous advanced colorectal neoplasm

BACKGROUND AND STUDY AIMS

Exercise is associated with a lower risk of colorectal neoplasm but its association with metachronous advanced colorectal neoplasm development after polypectomy remains unclear. We aimed to investigate associations between subjects' exercise habits and the risk of metachronous advanced colorectal neoplasm.

PATIENTS AND METHODS

This study analyzed subjects older than 40 years who received screening colonoscopy with polypectomy and surveillance colonoscopy between January 2009 and December 2016. All participants completed a standard questionnaire containing exercise habits before surveillance colonoscopy. Subjects' exercise habits were quantified as weekly exercise amounts (metabolic equivalents of task-day/week) and dichotomized (active/sedentary exercise habit) using averages as the cut-off point. The associations between incidence of metachronous advanced colorectal neoplasm and exercise habits were evaluated using Kaplan-Meier analysis and Cox regression models.

RESULTS

A total of 1820 subjects comprised the study cohort and 86 (4.73%) of them developed metachronous advanced colorectal neoplasm during the surveillance period. An active exercise habit after polypectomy was associated with a lower risk of metachronous advanced colorectal neoplasm (adjusted hazard ratio [aHR] 0.57, 95% confidence interval [CI] 0.35-0.91). Furthermore, this protective effect from exercise was specific for subjects having advanced neoplasm at screening colonoscopy (aHR 0.32, 95% CI 0.11-0.94).

CONCLUSIONS

An active exercise habit after polypectomy, a surrogate for a more active lifestyle, is associated with a lower risk for developing metachronous advanced colorectal neoplasm. A positive lifestyle modification, such as maintaining/establishing an active exercise habit, should be advised after polypectomy, especially for those with advanced colorectal neoplasm during screening.

Incidence of Colorectal Adenomas After Bariatric Surgery: Pre-operative Super Morbid Obesity Is Independently Associated with Increased Risk

PURPOSE

The impact of pre-bariatric surgery BMI on the incidence of colorectal adenomas in the post-operative period is unknown. Here we aim to evaluate the incidence of colorectal adenomas after bariatric surgery and to assess super morbid obesity (SMO) as a risk factor for post-operative colorectal adenomas.

MATERIALS AND METHODS

An inception cohort of 1639 patients that underwent bariatric surgery between 2011 and 2019 in a referral center was retrospectively analyzed. SMO was defined as BMI > 50.0 kg/m². Cox regression analysis was performed to assess the influence of pre-operative BMI on the primary outcome.

RESULTS

A total 381 patients (23.2% of the cohort) underwent colonoscopy and included in the analysis. Mean age was 51.1 years (± 10.6) with mean BMI of 42.2 kg/m² (± 6.2), and 49 patients (12.9%) had SMO. Median time to colonoscopy was 3.5 years. One hundred nine patients (28.6%) had colorectal polyps, and 38/109 (34.8%) had advanced adenoma. Two patients had colorectal cancer (CRC). Pre-procedural SMO was associated with diagnosis of colorectal polyp (HR 2.4, 95% CI 1.5-3.9, p < 0.001) and advanced adenomas (HR 4.2, 95% CI 2.0-8.9, p < 0.001) upon adjustment to previously reported risk factors of CRC.

CONCLUSION

Pre-procedural SMO is associated with increased risk of colorectal adenomas after bariatric surgery compared to obese and morbidly obese individuals. Pre-operative BMI should be incorporated into post-operative screening plan in this population.

Increasing changes in visceral adiposity is associated with higher risk for colorectal adenoma: Multilevel analysis in a prospective cohort

BACKGROUND AND AIM

While many studies demonstrated an association between visceral adiposity and colorectal adenoma (CRA), the effect of longitudinal changes in body fat composition on CRA is unclear. We investigated the longitudinal association between changes in visceral adiposity and CRA occurrence.

METHODS

Between 2006 and 2018, 732 (62.8%) of the 1165 subjects in a prospective cohort voluntarily underwent follow-up abdominal fat computed tomography and colonoscopy. We defined incident and recurrent CRA as adenoma detected at follow-up colonoscopy from negative and positive adenoma at baseline colonoscopy, respectively. Multilevel survival analysis examined the longitudinal association between changes in visceral fat and CRA.

RESULTS

During a median follow-up of 7.4 years, 400 (54.6%) subjects developed CRA. In multivariable analysis, increasing changes in visceral adipose tissue (VAT) area were associated with higher risk of incident adenoma (hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.00-1.46 for change per 10 cm² increase; HR 1.79, 95% CI 1.08-2.97 for highest vs lowest quartile, P values for trend = 0.045). Likewise, increasing changes in VAT area were independently associated with a higher risk of recurrent adenoma (HR 1.35, 95% CI 1.13-1.62 for change per 10 cm² increase; HR 1.62, 95% CI 1.04-2.52 for highest vs lowest quartile, P values for trend = 0.001). Changes in subcutaneous adipose tissue area were not independently associated with CRA.

CONCLUSION

Increasing changes in VAT area were longitudinally associated with a higher risk of incident and recurrent CRA, independent of risk factors, suggesting that visceral adiposity may be an important target in CRA prevention.

Changes in Abdominal Obesity Affect the Risk of Metachronous Advanced Colorectal Neoplasia Development after Polypectomy

PURPOSE

The impact of changes in body mass index and waist circumference on the development of metachronous colorectal neoplasia (CRN) after polypectomy has rarely been examined. We evaluated the association between changes in overall/abdominal obesity and metachronous CRN risk.

MATERIALS AND METHODS

We studied patients who underwent ≥1 adenoma removal and surveillance colonoscopy. Patients were classified into the following four groups based on the changes in overall obesity from index to follow-up colonoscopy: non-obesity persisted (group 1), obesity to non-obesity (group 2), non-obesity to obesity (group 3), and obesity persisted (group 4). Patients were also divided into another four groups based on similar changes in abdominal obesity (groups 5-8).

RESULTS

The number of patients in groups 1, 2, 3, and 4 was 5074, 457, 643, and 3538, respectively, and that in groups 5, 6, 7, and 8 was 4229, 538, 656, and 2189, respectively. Group 4 had a significantly higher risk of metachronous CRN compared to groups 1 and 2. However, metachronous advanced CRN (ACRN) risk was not different among groups 1, 2, 3, and 4. Metachronous CRN risk in group 8 (abdominal obesity persisted) was higher than that in groups 5 (non-abdominal obesity persisted) and 7 (non-abdominal obesity to abdominal obesity), and tended to be higher than that in group 6 (abdominal obesity to non-abdominal obesity). Additionally, group 8 had a significantly higher risk of metachronous ACRN compared to groups 5, 6, and 7.

CONCLUSION

Changes in obesity affected the metachronous CRN risk. In particular, changes in abdominal obesity affected the metachronous ACRN risk.

Visceral obesity as a risk factor for colorectal adenoma occurrence in surveillance colonoscopy

BACKGROUND AND AIMS

The aim of this study was to examine the prospective association between visceral obesity and the incidence and recurrence of colorectal adenoma.

METHODS

We conducted a cohort study involving 2244 participants between 2006 and 2007. The study participants were prospectively followed until 2014 according to the initial colonoscopy and histopathology findings. Incident and recurrent colorectal adenoma groups were defined as individuals with a positive follow-up colonoscopy result from the normal results and adenoma groups, respectively, at the baseline colonoscopy.

RESULTS

Among the 1163 patients (51.8%) who received a follow-up colonoscopy, 509 (43.8%) and 654 (56.2%) were grouped into the normal and adenoma cohorts. Colorectal adenomas occurred in 592 patients (50.9%) during the median period of 43 months, with an incident adenoma prevalence of 39.1% and a recurrent adenoma prevalence of 60.1%. An increase in the visceral adipose tissue (VAT) area was associated with a higher incidence of adenoma (highest quintile vs lowest quintile of the VAT hazard ratios [HRs], 2.16; 95% confidence interval [CI], 1.26-3.71; HR 1.32 [per 1-standard deviation]; 95% CI, 1.10-1.60) in the multivariable analysis. Increases in body mass index and waist circumference were associated with recurrent adenomas (HR 1.33 [per 1 kg/m²], 95% CI, 1.18-1.46; HR 1.04 [per 1 cm], 95% CI, 1.01-1.07, respectively) in the multivariate analysis.

CONCLUSION

A higher VAT area was dose-dependently associated with a higher risk of incident adenoma. Furthermore, increases in body mass index and waist circumference as surrogate markers of abdominal obesity were associated with a higher risk of recurrent adenoma.

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

Background

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

Methods

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

Results

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

Conclusions

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

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.

Epidemiology and biology of physical activity and cancer recurrence

Physical activity is emerging from epidemiologic research as a lifestyle factor that may improve survival from colorectal, breast, and prostate cancers. However, there is considerably less evidence relating physical activity to cancer recurrence and the biologic mechanisms underlying this association remain unclear. Cancer patients are surviving longer than ever before, and fear of cancer recurrence is an important concern. Herein, we provide an overview of the current epidemiologic evidence relating physical activity to cancer recurrence. We review the biologic mechanisms most commonly researched in the context of physical activity and cancer outcomes, and, using the example of colorectal cancer, we explore hypothesized mechanisms through which physical activity might intervene in the colorectal recurrence pathway. Our review highlights the importance of considering pre-diagnosis and post-diagnosis activity, as well as cancer stage and timing of recurrence, in epidemiologic studies. In addition, more epidemiologic research is needed with cancer recurrence as a consistently defined outcome studied separately from survival. Future mechanistic research using randomized controlled trials, specifically those demonstrating the exercise responsiveness of hypothesized mechanisms in early stages of carcinogenesis, are needed to inform recommendations about when to exercise and to anticipate additive or synergistic effects with other preventive behaviors or treatments.

Gastrointestinal Complications of Obesity

Obesity usually is associated with morbidity related to diabetes mellitus and cardiovascular diseases. However, there are many gastrointestinal and hepatic diseases for which obesity is the direct cause (eg, nonalcoholic fatty liver disease) or is a significant risk factor, such as reflux esophagitis and gallstones. When obesity is a risk factor, it may interact with other mechanisms and result in earlier presentation or complicated diseases. There are increased odds ratios or relative risks of several gastrointestinal complications of obesity: gastroesophageal reflux disease, erosive esophagitis, Barrett's esophagus, esophageal adenocarcinoma, erosive gastritis, gastric cancer, diarrhea, colonic diverticular disease, polyps, cancer, liver disease including nonalcoholic fatty liver disease, cirrhosis, hepatocellular carcinoma, gallstones, acute pancreatitis, and pancreatic cancer. Gastroenterologists are uniquely poised to participate in the multidisciplinary management of obesity as physicians caring for people with obesity-related diseases, in addition to their expertise in nutrition and endoscopic interventions.

Parameters of Glucose and Lipid Metabolism Affect the Occurrence of Colorectal Adenomas Detected by Surveillance Colonoscopies

PURPOSE

Limited data are available regarding the associations between parameters of glucose and lipid metabolism and the occurrence of metachronous adenomas. We investigated whether these parameters affect the occurrence of adenomas detected on surveillance colonoscopy.

MATERIALS AND METHODS

This longitudinal study was performed on 5289 subjects who underwent follow-up colonoscopy between 2012 and 2013 among 62171 asymptomatic subjects who underwent an initial colonoscopy for a health check-up between 2010 and 2011. The risk of adenoma occurrence was assessed using Cox proportional hazards modeling.

RESULTS

The mean interval between the initial and follow-up colonoscopy was 2.2±0.6 years. The occurrence of adenomas detected by the follow-up colonoscopy increased linearly with the increasing quartiles of fasting glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglycerides measured at the initial colonoscopy. These associations persisted after adjusting for confounding factors. The adjusted hazard ratios for adenoma occurrence comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, and triglycerides were 1.50 [95% confidence interval (CI), 1.26-1.77; p(trend)<0.001], 1.22 (95% CI, 1.04-1.43; p(trend)=0.024), 1.22 (95% CI, 1.02-1.46; p(trend)=0.046), 1.36 (95% CI, 1.14-1.63; p(trend)=0.004), and 1.19 (95% CI, 0.99-1.42; p(trend)=0.041), respectively. In addition, increasing quartiles of low-density lipoprotein-cholesterol and apolipoprotein B were associated with an increasing occurrence of adenomas.

CONCLUSION

The levels of parameters of glucose and lipid metabolism were significantly associated with the occurrence of adenomas detected on surveillance colonoscopy. Improving the parameters of glucose and lipid metabolism through lifestyle changes or medications may be helpful in preventing metachronous adenomas.

Helicobacter pylori infection is an independent risk factor for colonic adenomatous neoplasms

PURPOSE

Helicobacter pylori infection is considered to have a positive association with colorectal neoplasms. In this study, we evaluated the association between H. pylori infection and colorectal adenomas, based on the characteristics of these adenomas in Korea, where the prevalence of H. pylori infection is high and the incidence of colorectal cancer continues to increase.

METHODS

The study cohort consisted of 4,466 subjects who underwent colonoscopy and esophagogastroduodenoscopy during screening (1,245 colorectal adenomas vs. 3,221 polyp-free controls). We compared the rate of H. pylori infection between patients with adenoma and polyp-free control cases, using multivariable logistic regression analysis.

RESULTS

The overall rate of positive H. pylori infection was higher in adenoma cases than in polyp-free control cases (55.0 vs. 48.5%, p < 0.001). The odds ratio (OR) of positive H. pylori infection in patients with adenoma compared to polyp-free controls was 1.28 (95% CI 1.11-1.47). The positive association of H. pylori infection with colorectal adenomas was more prominent in advanced adenomas (OR 1.84, 95% CI 1.25-2.70) and multiple adenomas (OR 1.72, 95% CI 1.26-2.35). Based on the location of these adenomas, the OR was significant only in patients with colonic adenomas (OR 1.31, 95% CI 1.13-1.52) and not in those with rectal adenoma (OR 0.85, 95% CI 0.58-1.24).

CONCLUSION

Helicobacter pylori infection is an independent risk factor for colonic adenomas, especially in cases of advanced or multiple adenomas, but not for rectal adenomas.

Weight loss following diet-induced obesity does not alter colon tumorigenesis in the AOM mouse model

Obesity presents a significant public health concern given its association with increased cancer incidence, unfavorable prognosis, and metastasis. However, there is very little literature on the effects of weight loss, following obesity, on risk for colon cancer or liver cancer. Therefore, we sought to study whether intentional weight loss through diet manipulation was capable of mitigating colon and liver cancer in mice. We fed mice with a high-fat diet (HFD) comprised of 47% carbohydrates, 40% fat, and 13% protein for 20 wk to mimic human obesity. Subsequently, azoxymethane (AOM) was used to promote colon and liver carcinogenesis. A subset of obese mice was then switched to a low-fat diet (LFD) containing 67.5% carbohydrate, 12.2% fat, and 20% protein to promote intentional weight loss. Body weight loss and excess fat reduction did not protect mice from colon cancer progression and liver dysplastic lesion in the AOM-chemical-cancer model even though these mice had improved blood glucose and leptin levels. Intentional weight loss in AOM-treated mice actually produced histological changes that resemble dysplastic alterations in the liver and presented a higher percentage of F4/80⁺CD206⁺ macrophages and activated T cells (CD4⁺CD69⁺) in the spleen and lymph nodes, respectively. In addition, the liver of AOM-treated mice exposed to a HFD during the entire period of the experiment exhibited a marked increase in proliferation and pNF-κB activation. Altogether, these data suggest that intentional weight loss following chemical-induced carcinogenesis does not affect colon tumorigenesis but may in fact negatively impact liver repair mechanisms.

Diet-induced weight loss leads to a switch in gene regulatory network control in the rectal mucosa

BACKGROUND

Weight loss may decrease risk of colorectal cancer in obese individuals, yet its effect in the colorectum is not well understood. We used integrative network modeling, Passing Attributes between Networks for Data Assimilation, to estimate transcriptional regulatory network models from mRNA expression levels from rectal mucosa biopsies measured pre- and post-weight loss in 10 obese, pre-menopausal women.

RESULTS

We identified significantly greater regulatory targeting of glucose transport pathways in the post-weight loss regulatory network, including "regulation of glucose transport" (FDR=0.02), "hexose transport" (FDR=0.06), "glucose transport" (FDR=0.06) and "monosaccharide transport" (FDR=0.08). These findings were not evident by gene expression analysis alone. Network analysis also suggested a regulatory switch from NFΚB1 to MAX control of MYC post-weight loss.

CONCLUSIONS

These network-based results expand upon standard gene expression analysis by providing evidence for a potential mechanistic alteration caused by weight loss.

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.

Metabolic syndrome is a risk factor for adenoma occurrence at surveillance colonoscopy: A single-center experience in Korea

We investigated the risk factors for adenoma occurrence at surveillance colonoscopy, especially focusing on patient characteristics, including metabolic factors.Surveillance colonoscopy intervals depend on baseline adenoma characteristics. However, patients' characteristics may also influence the occurrence of adenomas.Of 62,171 asymptomatic subjects who underwent colonoscopy for a health check-up between 2010 and 2011, 4869 subjects who underwent follow-up colonoscopy between 2012 and 2013 were included in this longitudinal study. The risk of adenoma occurrence was assessed using Cox proportional hazards modeling.Of 4869 subjects, 2827 (58.1%), 1619 (33.3%), and 423 (8.7%) were assigned to the normal, low-risk, and high-risk groups, respectively, according to baseline adenoma characteristics. The mean interval between initial and follow-up colonoscopy was 2.2 ± 0.6 years. Certain patient factors, including older age (≥50 years; adjusted hazard ratio [aHR], 2.08; 95% CI, 1.73-2.49), male sex (aHR, 1.69; 95% CI, 1.30-2.19), metabolic syndrome (MetS) (aHR, 1.28; 95% CI, 1.09-1.51), obesity (aHR, 1.17; 95% CI, 1.02-1.34), elevated fasting blood glucose levels (aHR, 1.37; 95% CI, 1.19-1.58), and elevated triglyceride levels (aHR, 1.19; 95% CI, 1.03-1.37), as well as baseline adenoma characteristics, were associated with a higher risk of adenoma occurrence at follow-up colonoscopy. The cumulative incidence of adenoma occurrence in the high-risk group was higher than that in the low-risk group, whereas the incidence in the high-risk group without MetS was comparable with that in the low-risk group with MetS.Patient characteristics, such as MetS, obesity, older age, and male sex, in addition to adenoma characteristics, were independent risk factors for adenoma occurrence at surveillance colonoscopy. These patient characteristics may be considered in surveillance colonoscopy intervals.

Health disparities in colorectal cancer among racial and ethnic minorities in the United States

In the 2010 Census, just over one-third of the United States (US) population identified themselves as being something other than being non-Hispanic white alone. This group has increased in size from 86.9 million in 2000 to 111.9 million in 2010, representing an increase of 29 percent over the ten year period. Per the American Cancer Society, racial and ethnic minorities are more likely to develop cancer and die from it when compared to the general population of the United States. This is particularly true for colorectal cancer (CRC). The primary aim of this review is to highlight the disparities in CRC among racial and ethnic minorities in the United States. Despite overall rates of CRC decreasing nationally and within certain racial and ethnic minorities in the US, there continue to be disparities in incidence and mortality when compared to non-Hispanic whites. The disparities in CRC incidence and mortality are related to certain areas of deficiency such as knowledge of family history, access to care obstacles, impact of migration on CRC and paucity of clinical data. These areas of deficiency limit understanding of CRC's impact in these groups and when developing interventions to close the disparity gap. Even with the implementation of the Patient Protection and Affordable Healthcare Act, disparities in CRC screening will continue to exist until specific interventions are implemented in the context of each of racial and ethnic group. Racial and ethnic minorities cannot be viewed as one monolithic group, rather as different segments since there are variations in incidence and mortality based on natural history of CRC development impacted by gender, ethnicity group, nationality, access, as well as migration and socioeconomic status. Progress has been made overall, but there is much work to be done.

Obesity and Cecal Intubation Time

Background/Aims:

Obesity is a much-debated factor with conflicting evidence regarding its association with cecum intubation rates during colonoscopy. We aimed to identify the association between cecal intubation (CI) time and obesity by eliminating confounding factors.

Methods:

A retrospective chart review of subjects undergoing outpatient colonoscopy was conducted. The population was categorized by sex and obesity (body mass index [BMI, kg/m²]: I, <24.9; II, 25 to 29.9; III, ≥30). CI time was used as a marker for a difficult colonoscopy. Mean CI times (MCT) were compared for statistical significance using analysis of variance tests.

Results:

A total of 926 subjects were included. Overall MCT was 15.7±7.9 minutes, and it was 15.9±7.9 and 15.5±7.9 minutes for men and women, respectively. MCT among women for BMI category I, II, and III was 14.4±6.5, 15.5±8.3, and 16.2±8.1 minutes (p=0.55), whereas for men, it was 16.3±8.9, 15.9±8.0, and 15.6±7.2 minutes (p=0.95), respectively.

Conclusions:

BMI had a positive association with CI time for women, but had a negative association with CI for men.

Effects of metabolic syndrome and findings from baseline colonoscopies on occurrence of colorectal neoplasms

BACKGROUND & AIMS

Metabolic syndrome is associated with increased risk of colorectal neoplasm, but little is known about its effects on the occurrence of neoplasm after colonoscopy. We investigated the effects of metabolic syndrome on the risk of advanced neoplasm after colonoscopy.

METHODS

We performed a prospective study of 4483 subjects age 50 years and older who underwent screening and surveillance colonoscopies as part of an annual health check-up at National Taiwan University Hospital. Baseline demographic data and colonoscopic findings were recorded. Subjects with either advanced adenoma or 3 or more adenomas detected at baseline were classified as high risk; those with fewer than 3 nonadvanced adenomas were classified as low risk; and those without any neoplastic lesions were classified as normal. The cumulative risk of detecting an advanced neoplasm during surveillance colonoscopies (3 and 5 years later) was correlated with risk group and metabolic syndrome. Hazard ratios (HRs) were calculated for occurrence of neoplasm according to baseline colonoscopic findings and clinical risk factors, including metabolic syndrome.

RESULTS

Advanced neoplasms were detected during the surveillance colonoscopies in 1.3% of subjects in the normal group and in 2.4% of those in the low-risk group at 5 years, and in 8.5% of subjects in the high-risk group at 3 years. Subjects with metabolic syndrome had a significantly higher risk for subsequent advanced neoplasms (P < .0001). After stratification based on findings from baseline colonoscopies, the risk for neoplasm was significant in the normal (P < .001) and low-risk groups (P = .04), but not in the high-risk group (P = .48). In Cox regression analysis, metabolic syndrome had significant effects on the risk for advanced neoplasms in the normal (HR, 2.07; 95% confidence interval, 1.13-3.81) and low-risk groups (HR, 2.34; 95% confidence interval, 1.01-5.41), but not in the high-risk group.

CONCLUSIONS

Metabolic syndrome is a significant risk factor for occurrence of an advanced adenoma after a negative or low-risk finding from a baseline colonoscopy. Metabolic syndrome should be considered in risk stratification for surveillance intervals.

Do recent epidemiologic observations impact who and how we should screen for CRC?

Colorectal cancer (CRC) screening is recommended to begin at age 50 for those patients with no significant family history of CRC. However, even within this group of average-risk patients, there is data to suggest that there may be variation in CRC risk. These observations suggest that perhaps CRC screening should be tailored to target those patients at higher risk for earlier or more invasive screening as compared to those individuals at lower risk. The strategy of how to identify those higher-risk patients may not be straightforward. One method might be to use single risk factors such as smoking or elevated BMI as has been suggested in the recent American College of Gastroenterology CRC screening guidelines. Another paradigm involves the use of models which incorporate several risk factors to stratify patients by risk. This article will highlight recent large studies that examine recognized CRC risk factors as well as review recently developed CRC risk models. There will also be a discussion of the application of these factors and models in an effort to make CRC screening more efficient.

Body mass index and colon cancer screening: The road ahead

Screening for colorectal cancer (CRC) has been associated with a decreased incidence and mortality from CRC. However, patient adherence to screening is less than desirable and resources are limited even in developed countries. Better identification of individuals at a higher risk could result in improved screening efforts. Over the past few years, formulas have been developed to predict the likelihood of developing advanced colonic neoplasia in susceptible individuals but have yet to be utilized in mass screening practices. These models use a number of clinical factors that have been associated with colonic neoplasia including the body mass index (BMI). Advances in our understanding of the mechanisms by which obesity contributes to colonic neoplasia as well as clinical studies on this subject have proven the association between BMI and colonic neoplasia. However, there are still controversies on this subject as some studies have arrived at different conclusions on the influence of BMI by gender. Future studies should aim at resolving these discrepancies in order to improve the efficiency of screening strategies.

Excess adiposity and gastrointestinal cancer

BACKGROUND

Excess adiposity is a risk factor for incidence of several gastrointestinal cancers, but it is unclear how these epidemiological observations translate into clinical practice.

METHODS

Critical appraisals and updated analyses of published systematic reviews were undertaken to quantify cancer risk associations better and to assess the impact of weight-reducing strategies (surgical and non-surgical) on cancer prevention.

RESULTS AND CONCLUSION

A large volume of evidence demonstrates that body mass index (BMI), as an approximation for general adiposity, is a risk factor for the development of oesophageal adenocarcinoma, and colorectal, hepatocellular, gallbladder and pancreatic cancers. A smaller volume of evidence demonstrates that indices of increased central adiposity (such as waist circumference) are associated with increased risk of oesophageal adenocarcinoma and colorectal cancer, but these indices are not necessarily better predictors of risk compared with BMI. Several biological mechanisms may explain these associations but each hypothesis has several caveats and weaknesses. There are few data that convincingly demonstrate significant reductions in risk of gastrointestinal cancers following weight-reducing strategies. In turn, there are many methodological pitfalls in this literature, which prevent conclusive interpretation. The lack of robust intermediary obesity-related biomarkers is an additional unresolved challenge for prevention trials. Novel underpinning mechanisms (for example, local ectopic fat) and more accurate methods to measure these intermediaries are sought and explored as the most optimistic research strategies for the future.

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.

Gastrointestinal morbidity in obesity

Obesity is a complex disease that results from increased energy intake and decreased energy expenditure. The gastrointestinal system plays a key role in the pathogenesis of obesity and facilitates caloric imbalance. Changes in gastrointestinal hormones and the inhibition of mechanisms that curtail caloric intake result in weight gain. It is not clear if the gastrointestinal role in obesity is a cause or an effect of this disease. Obesity is often associated with type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). Obesity is also associated with gastrointestinal disorders, which are more frequent and present earlier than T2DM and CVD. Diseases such as gastroesophageal reflux disease (GERD), cholelithiasis, or nonalcoholic steatohepatitis are directly related to body weight and abdominal adiposity. Our objective is to assess the role of each gastrointestinal organ in obesity and the gastrointestinal morbidity resulting in those organs from the effects of obesity.

Colorectal cancer disparities: Issues, controversies and solutions

Colorectal cancer (CRC) is the second leading cause of cancer related deaths in the United States. There are significant differences in CRC incidence and mortality by race with the highest burden occurring among blacks. The underlying factors contributing to CRC disparities are multiple and complex. Studies have suggested that a higher prevalence of putative risk factors for CRC, limited access to healthcare services, lower utilization of healthcare resources and increased biological susceptibilities contribute to this disparity by race. This article reviews the factors associated with the disproportionally higher burden of CRC among blacks; addresses the controversies regarding the age to begin CRC screening and the screening modality to use for blacks; and proffers solutions to eliminate CRC disparity by race.