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

Exercise Affects Mucosa-Associated Microbiota and Colonic Tumor Formation Induced by Azoxymethane in High-Fat-Diet-Induced Obese Mice

The only reliable factor that reduces the risk of colorectal carcinogenesis is physical activity. However, the underlying mechanisms remain unclear. In this study, we examined the effects of physical activity against gut microbiota, including mucosa-associated microbiota (MAM) on azoxymethane-induced colorectal tumors in obese mice. We divided the subjects into four groups: normal diet (ND), high-fat diet (HFD), ND + exercise (Ex), and HFD + Ex groups. The Ex group performed treadmill exercise for 20 weeks. Thereafter, fecal and colonic mucus samples were extracted for microbiota analysis. DNA was collected from feces and colonic mucosa, and V3-V4 amplicon sequencing analysis of the 16SrRNA gene was performed using MiSeq. The HFD group had significantly more colonic polyps than the ND group (ND 6.5 ± 1.3, HFD 11.4 ± 1.5, p < 0.001), and the addition of Ex suppressed the number of colonic polyps in ND and HFD groups (ND 6.5 ± 1.3, ND + Ex 2.8 ± 2.5, p < 0.05). The HFD group showed significantly lower concentrations of succinic, acetic, butyric, and propionic acids (mg/g) in feces, compared with the ND group (succinic acid HFD 0.59, ND 0.17; acetic acid HFD 0.63, ND 2.41; propionic acid HFD 0.10, ND 0.47; and N-butyric acid HFD 0.31, ND 0.93). In the case of ND, succinic acid and butyric acid tended to decrease with Ex (succinic acid ND 0.17, ND + Ex 0.12; N-butyric acid ND 0.93, ND + Ex 0.74 0.74). Succinic acid, acetic acid, butyric acid, and propionic acid levels in feces were significantly lower in the HFD group than in the ND group; in both feces and mucus samples, Butyricicoccus and Lactobacillus levels were significantly lower in the HFD group. Akkermansia was significantly increased in ND + Ex and HFD + Ex groups. Diet and exercise affected the number of colorectal tumors. Furthermore, diet and exercise alter intestinal MAM, which may be involved in colorectal tumor development.

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.

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.

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.

Efficacy, safety, and tolerability of a ready-to-drink bowel preparation in overweight and obese adults: subanalysis by body mass index from a phase III, assessor-blinded study

BACKGROUND

We performed a post hoc secondary analysis for the effect of body mass index (BMI) on the efficacy, tolerability, and safety of ready-to-drink sodium picosulfate, magnesium oxide, and citric acid (SPMC oral solution) bowel preparation.

METHODS

A phase III, randomized, assessor-blinded, multicenter, noninferiority study was conducted comparing split-dose, low-volume SPMC oral solution with a powder formulation for oral solution. A post hoc secondary analysis assessed efficacy, safety, and tolerability of SPMC oral solution stratified by BMI. BMI was classified by Centers for Disease Control and Prevention definitions (underweight and normal weight: BMI < 25 kg/m²; overweight: BMI 25-29.9 kg/m²; class I obesity: BMI 30-34.9 kg/m²; class II obesity: BMI 35-39.9 kg/m²; class III/severe obesity: BMI ⩾40 kg/m²). Prespecified primary efficacy endpoint ('responders') was the proportion of participants with 'excellent' or 'good' ratings on a modified Aronchick Scale (AS). Secondary efficacy outcomes were the quality of cleansing of the right colon as assessed by the Boston Bowel Preparation Scale (BBPS); as well as selected findings from the Mayo Clinic Bowel Prep Tolerability Questionnaire. Safety assessments included adverse events (AEs) and laboratory evaluations.

RESULTS

Between 82.8% and 92.5% of participants in any BMI group were responders by AS, and between 91.3% and 100% were responders by BBPS in the right colon. Efficacy was consistent across BMI groups, with no clear trends. Greater than 83% of participants in any BMI group found the preparation 'easy' or 'acceptable' to ingest, and the majority (>58%) rated SPMC oral solution as 'better' than a prior bowel preparation. In all BMI groups, safety data were similar to the overall cohort. Commonly reported, drug-related, treatment-emergent AEs were, by ascending BMI group, nausea (1.1%, 5.3%, 1.0%, 5.7%, and 0%) and headache (1.1%, 4.1%, 1.0%, 5.7%, and 0%).

CONCLUSIONS

Ready-to-drink SPMC oral solution had consistent, good quality colon cleansing, and favorable tolerability among participants of all BMI groups.

CLINICALTRIALSGOV REGISTRATION

NCT03017235.

Attenuated polyposis of the large bowel: a morphologic and molecular approach

Attenuated polyposis could be defined as a variant of familial adenomatous polyposis (FAP) in which synchronous polyps of the large bowel range between 10 and 99. We analysed all cases of attenuated polyposis observed over the last 30 years with the objectives: (A) to classify the disease according to different type and proportion of polyps; (B) To ascertain the contribution of APC and MutYH genes; (C) to discover features which could arise the suspicion of mutations; (D) To obtain indications for management and follow-up. 84 individuals in 82 families were studied. Polyps were classified into four groups as adenoma, hyperplastic, other serrated lesions or others; APC and MutYH mutations were assessed. Mean age at diagnosis was 54 ± 14 years in men and 48 ± 13 in women (P = 0.005). Polyps were more numerous in women (37 ± 26 vs 29 ± 22). Sixty % of patients underwent bowel resection, mainly for cancer; the remaining were managed through endoscopy. A total of 2586 polyps were detected at diagnostic endoscopy: 2026 (80 %) were removed and analysed. Adenomas were diagnosed in 1445 (70 %), hyperplastic polyps in 541 (26 %), other serrated lesions in 61 (2.9 %). Adenomas and hyperplastic lesions were detected in the majority of patients. In 68 patients (81 %) in whom studies were executed, APC mutations were found in 8 and MutYH mutations in 10. Genetic variants were more frequent in women (12 vs 6, P = 0.039). Taking into consideration the prevalent (>50 %) histology and presence of mutations, patients could be subdivided into four groups: (1) APC mutated polyposis (AFAP), when adenomas were >50 % and APC mutations detected (no. 8, 10 %); (2) MutYH mutated polyposis (MAP), adenomas >50 % and biallelic MutYH mutations (no. 10, 12 %); (1) attenuated polyposis without detectable mutations, prevalence of adenomas, 48 cases (57 %); (1) hyperplastic-serrated polyposis, with prevalence (>50 %) of hyperplastic/other serrated lesions and no constitutional mutation (no. 18, 21 %). Aggregation of tumors, cancer in probands, distribution of polyps and other clinical characteristics showed no difference among the four groups. In conclusions, AFAP and MAP, the polyposis labeled by constitutional mutations, represented about 25 % of all attenuated polyposis. Mutation-associated cases showed an earlier age of onset of polyps and were more frequent in the female sex.

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.

Lifestyle Risk Factors for Serrated Colorectal Polyps: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Certain subsets of colorectal serrated polyps (SP) have malignant potential. We performed a systematic review and meta-analysis to investigate the association between modifiable lifestyle factors and risk for SPs.

METHODS

We conducted a systematic search of Medline, Embase, and Web of Science for observational or interventional studies that contained the terms risk or risk factor, and serrated or hyperplastic, and polyps or adenomas, and colorectal (or synonymous terms), published by March 2016. Titles and abstracts of identified articles were independently reviewed by at least 2 reviewers. Adjusted relative risk (RR) and 95% confidence interval (CI) were combined using random effects meta-analyses to assess the risk of SP, when possible.

RESULTS

We identified 43 studies of SP risk associated with 7 different lifestyle factors: smoking, alcohol, body fatness, diet, physical activity, medication, and hormone-replacement therapy. When we compared the highest and lowest categories of exposure, factors we found to significantly increase risk for SP included tobacco smoking (RR, 2.47; 95% CI, 2.12-2.87), alcohol intake (RR, 1.33; 95% CI, 1.17-1.52), body mass index (RR, 1.40; 95% CI, 1.22-1.61), and high intake of fat or meat. Direct associations for smoking and alcohol, but not body fat, tended to be stronger for sessile serrated adenomas/polyps than hyperplastic polyps. In contrast, factors we found to significantly decrease risks for SP included use of nonsteroidal anti-inflammatory drugs (RR, 0.77; 95% CI, 0.65-0.92) or aspirin (RR, 0.81; 95% CI, 0.67-0.99), as well as high intake of folate, calcium, or fiber. No significant associations were detected between SP risk and physical activity or hormone replacement therapy.

CONCLUSIONS

Several lifestyle factors, most notably smoking and alcohol, are associated with SP risk. These findings enhance our understanding of mechanisms of SP development and indicate that risk of serrated pathway colorectal neoplasms could be reduced with lifestyle changes.

Polyp Detection Rates among Body Mass Index Categories at First Screening Colonoscopy

In the United States, obesity is an epidemic and colorectal cancer is the second deadliest cancer for men and women. A link between obesity and colorectal adenomas and carcinoma has been suggested but not proven. We sought out to determine if obesity was associated with increased rates of polyp formation. All patients undergoing a first screening colonoscopy by one of the participating endoscopists at Thomas Jefferson University Hospital from January 2012 to March 2015 were considered for the study. Their demographics, body mass index (BMI), and colonoscopy findings were recorded at the time of the procedure and prospectively maintained in our database. The final pathologic diagnosis was recorded for each participant as it became available. A total of 758 subjects were included. Of these, 22 per cent had a BMI <25 kg/m2, 29 per cent had a BMI between 25 and 29.9 kg/m2, and 49 per cent had a BMI of at least 30 kg/m2. Overall, 21.9 per cent of the participants were found to have at least one adenomatous polyp. The polyp detection rates were 24.4 per cent in the group with a BMI less than 25, 20.5 per cent in the overweight group, and 21.6 per cent in the obese group. Our study included 56 super obese individuals with a BMI ≥45 kg/m2. About 17.9 per cent of subjects in the super obese group had an adenomatous polyp. There were no differences in the incidence of adenomatous polyps between BMI categories in our study.

The relationship of vitamin D status, smoking, and colorectal adenoma: a retrospective study in an ethnically diverse community

OBJECTIVE

Circulating 25-hydroxyvitamin D (25OHD) level is suggested to be negatively correlated with risk of colorectal cancer (CRC) and colorectal adenoma (CRA), but most of the epidemiological data were originated amongst Caucasians and African Americans. This study aimed to investigate the relationship between vitamin D status, smoking and CRA in an ethnically diverse community with a high Hispanic density.

METHODS

In this retrospective study, we included 233 patients who underwent complete colonoscopies from 2009 to 2011, and their serum 25OHD levels in the winter season had been measured. Among them, 65 adenoma cases and 168 adenoma-free controls were identified and evaluated for the association of CRA with smoking, ethnicity and serum 25OHD level using unstratified and stratified multivariate logistic regression analyses.

RESULTS

In our study participants, the mean serum 25OHD level and the percentage of Hispanics were lower in the adenoma group versus the control group, while no black-white difference was noted in the CRA prevalence. When adjusted for 25OHD level, the lower rate of adenoma in Hispanics compared to non-Hispanics was attenuated and became statistically insignificant. A mild protective effect of vitamin D (6% reduction) on the CRA risk was found significant for active smokers, but not for non-smokers. A detrimental impact of smoking in the CRA risk was only shown among non-Hispanic patients, but not among Hispanics irrespective of vitamin D status.

CONCLUSIONS

Our data suggest a marked distinction between Hispanics and non-Hispanics in the risk of CRA. The reduced adenoma prevalence among Hispanics vs. non-Hispanics could be partially explained by vitamin D status, cigarette smoking and their interactions. Future larger-sized multi-center studies on vitamin D status and ethnicity, as well as dietary, behavioral, genetic factors and their interactions for CRA and CRC are needed. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Physical activity and other lifestyle factors in relation to the prevalence of colorectal adenoma: a colonoscopy-based study in asymptomatic Koreans

PURPOSE

To evaluate physical activity and other lifestyle risk factors in relation to the prevalence of colorectal adenomas in asymptomatic Koreans.

METHODS

A total of 1,526 asymptomatic subjects who underwent a colonoscopy were enrolled. Lifestyle factors such as physical activity and smoking data were obtained using a questionnaire. The subjects were grouped into three exposure levels by tertiles of metabolic equivalent hours per week. We evaluated the risk factors in subjects with adenomas by risk stratification (low-risk adenoma group vs. high-risk adenoma group) and by anatomic location (proximal colon, distal colon, rectum, and multiple locations). The high-risk adenoma group was defined as subjects with advanced adenomas or multiple (≥ 3) adenomas.

RESULTS

A total of 456 participants had colorectal adenomas, and 861 had no polyps. In multivariate analyses, higher levels of physical activity were associated with a significantly decreased risk of colorectal adenomas (OR = 0.56, 95% CI 0.40-0.79). This inverse association was stronger for the risk of high-risk adenomas (OR = 0.39, 95% CI 0.21-0.73) than for low-risk adenomas (OR = 0.62, 95% CI 0.43-0.89). The negative relation of physical activity was significant for distal colon adenomas (OR = 0.54, 95% CI 0.30-0.95) and the adenomas with multiple locations (OR = 0.39, 95% CI 0.21-0.72).

CONCLUSIONS

Increased physical activity is associated with a reduced prevalence of colorectal adenomas. The inverse association between physical activity and adenoma was stronger for the risk of advanced or multiple adenomas.

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.

Five-year risk of colorectal neoplasia after normal baseline colonoscopy in asymptomatic Chinese Mongolian over 50 years of age

BACKGROUND

After normal colonoscopy, the 5-year risk of colorectal neoplasia is sufficiently low for asymptomatic people over 50 years of age. In China, the incidence of colorectal carcinoma of Mongolian people is higher than that of Han people. The aim of this study was to assess the 5-year risk of colorectal neoplasia after normal colonoscopy in asymptomatic Chinese Mongolian population.

PATIENTS AND METHODS

A cohort of asymptomatic Chinese Mongolian people (≥50 years old) were recruited and followed up with colonoscopy 5 years after colonoscopy. Baseline colonoscopy and follow-up colonoscopy findings were categorized based on the most advanced lesions: no adenoma, nonadvanced adenoma, and advanced adenoma. Five-year risk of colorectal neoplasia in these people was assessed according to the rates of no baseline adenoma and advanced adenoma at the end of 5 years.

RESULTS

A total of 480 of the 538 recruited people underwent follow-up colonoscopy at the end of 5 years. In people with no baseline adenoma, 27.3 % (82/301) was found to have any adenoma, and 1.7 % had advanced adenoma at follow-up colonoscopy. The risk of an advanced adenoma did not differ significantly between people with no adenoma at baseline and those with nonadvanced adenoma (relative risk (RR), 1.06; 95 % confidence interval (CI), 0.19-6.07). Advanced adenoma at baseline colonoscopy was the independent risk factor for advanced adenoma recurrence, compared with no adenoma at baseline (RR, 8.25; 95 % CI, 1.90-35.77).

CONCLUSION

The risk of advanced adenoma is low 5 years after the normal baseline colonoscopy, even in asymptomatic Chinese Mongolian population over 50 years of age.

Body mass index and risk of primary liver cancer: a meta-analysis of prospective studies

BACKGROUND

Questions remain about the dose-response relationship between body mass index (BMI) and primary liver cancer (PLC) risk, possible confounding by hepatitis virus infection, and differences by gender or geographic location. We performed a meta-analysis of prospective studies to explore these issues.

METHODS

We searched PubMed and Embase for studies of BMI and risk of PLC through November 30, 2011. Summary relative risks with their corresponding 95% confidence intervals (CIs) were calculated using a random effects model.

RESULTS

A total of 21 prospective studies (including 17,624 PLC cases) were included in our analysis. The summary relative risk for a 5-unit increment in BMI (in kg/m(2)) was 1.39 (95% CI: 1.25-1.55), with high heterogeneity. These positive results were robust when stratified by sex, geographic location, ascertainment of exposure and outcome, the number of cases, duration of follow-up, sample source, and cofounders. There was evidence of a nonlinear association between BMI and PLC risk, with the most pronounced increase in risk among persons with a BMI >32 kg/m(2). Patients with hepatitis C virus or cirrhosis (but not patients with hepatitis B virus) with excess weight had a higher risk of PLC development than general populations with excess weight.

CONCLUSION

Excess weight increases PLC risk. For people with HCV infection or cirrhosis, risk increases are greater than for general population.

Number of aberrant crypt foci in the rectum is a useful surrogate marker of colorectal adenoma recurrence

AIM

Endoscopic screening and removal of colorectal adenomas can reduce the incidence of colorectal cancer. However, given the possibility of adenoma recurrence, surveillance colonoscopy is currently recommended after the initial screening and removal of colorectal adenomas. Aberrant crypt foci (ACF) have been shown to serve as a reliable surrogate marker of colorectal carcinogenesis. In this study, the relationship between the number of ACF at the initial endoscopic polypectomy and the likelihood of colorectal adenoma recurrence after polypectomy were investigated.

METHODS

High-magnification chromoscopic colonoscopy was performed in 82 subjects who underwent endoscopic polypectomy to identify ACF in the lower rectum. Surveillance colonoscopy was then performed 3 years after the baseline polypectomy at Yokohama City University Hospital.

RESULTS

The number of ACF was greater in patients who showed adenoma recurrence (7.88 ± 6.35) than in those who did not (2.19 ± 2.95) (P < 0.001). Receiver-operating curve analysis showed that the number of ACF was a highly specific predictor of the risk of adenoma recurrence.

CONCLUSIONS

This is the first study conducted to investigate the relationship between the number of ACF after endoscopic polypectomy and the likelihood of recurrence of colorectal adenomas. These results suggest that the number of ACF is a useful predictor of the likelihood of colorectal adenoma recurrence.

Physical activity reduces risk for colon polyps in a multiethnic colorectal cancer screening population

Background

Identifying modifiable factors that influence the epidemiology of colorectal cancer incidence among multiethnic groups might be informative for the development of public health strategies targeting the disease. Minimal data exists describing the impact of physical activity on colorectal polyp risk in United States minority populations. The aim of this study is to evaluate the relationship of exercise on the prevalence of polyps in a multiethnic colorectal cancer screening population.

Results

We enrolled 982 patients: 558 Hispanic, 202 Asian,149 Black, and 69 White. Patients who reported exercising one or more hours weekly had a lower prevalence of any polyps (25.3% vs 33.2%, P = 0.008) as well as adenomas (13.8 vs. 18.9%, P = 0.03) compared to those who did not exercise. Black and Hispanic patients and those who were overweight or obese also had lower prevalence of polyps if they led an active lifestyle. Multivariate analysis revealed that age >55, male sex, and Black race/ethnicity were positively associated with the presence of adenomas, while a history of exercising one hour or more weekly was an independent negative predictor for the presence of adenomas anywhere in the colon (OR 0.67; 95% CI 0.4 - 0.9, P = 0.03).

Conclusions

Exercising one hour per week was associated with a lower prevalence of polyps and adenomas when compared to those who exercised less or not at all. An active lifestyle provides benefits to groups who are at risk for colorectal cancer, such as Blacks. It also provides significant protection to overweight and obese individuals. Public health initiatives should promote physical activity as a cancer prevention tool in multiethnic populations.

Trial registration

none

Aspirin inhibits mTOR signaling, activates AMP-activated protein kinase, and induces autophagy in colorectal cancer cells

BACKGROUND & AIMS

Aspirin reduces the incidence of and mortality from colorectal cancer (CRC) by unknown mechanisms. Cancer cells have defects in signaling via the mechanistic target of rapamycin (mTOR), which regulates proliferation. We investigated whether aspirin affects adenosine monophosphate-activated protein kinase (AMPK) and mTOR signaling in CRC cells.

METHODS

The effects of aspirin on mTOR signaling, the ribosomal protein S6, S6 kinase 1 (S6K1), and eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) were examined in CRC cells by immunoblotting. Phosphorylation of AMPK was measured; the effects of loss of AMPKα on the aspirin-induced effects of mTOR were determined using small interfering RNA (siRNA) in CRC cells and in AMPK(α1/α2-/-) mouse embryonic fibroblasts. LC3 and ULK1 were used as markers of autophagy. We analyzed rectal mucosa samples from patients given 600 mg aspirin, once daily for 1 week.

RESULTS

Aspirin reduced mTOR signaling in CRC cells by inhibiting the mTOR effectors S6K1 and 4E-BP1. Aspirin changed nucleotide ratios and activated AMPK in CRC cells. mTOR was still inhibited by aspirin in CRC cells after siRNA knockdown of AMPKα, indicating AMPK-dependent and AMPK-independent mechanisms of aspirin-induced inhibition of mTOR. Aspirin induced autophagy, a feature of mTOR inhibition. Aspirin and metformin (an activator of AMPK) increased inhibition of mTOR and Akt, as well as autophagy in CRC cells. Rectal mucosal samples from patients given aspirin had reduced phosphorylation of S6K1 and S6.

CONCLUSIONS

Aspirin is an inhibitor of mTOR and an activator of AMPK, targeting regulators of intracellular energy homeostasis and metabolism. These could contribute to its protective effects against development of CRC.

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.

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.

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.

Physical activity and risk of colon adenoma: a meta-analysis

BACKGROUND

Little evidence is available on the relation of physical activity with colon adenomas, a colon cancer precursor.

METHODS

We conducted a systematic literature review and meta-analysis of published studies (in English) through April 2010, examining physical activity or exercise and risk or prevalence of colon adenoma or polyp. Random effects models were used to estimate relative risks (RRs) and corresponding confidence intervals (CIs). A total of 20 studies were identified that examined the association and provided RRs and corresponding 95% CIs.

RESULTS

A significant inverse association between physical activity and colon adenomas was found with an overall RR of 0.84 (CI: 0.77-0.92). The association was similar in men (RR=0.81, CI: 0.67-0.98) and women (RR=0.87, CI: 0.74-1.02). The association appeared slightly stronger in large/advanced polyps (RR=0.70, CI: 0.56-0.88).

CONCLUSION

This study confirms previous reports of a significant inverse association of physical activity and colon adenoma, and suggests that physical activity can have an important role in colon cancer prevention.

Higher bone mineral density is associated with a decreased risk of colorectal adenomas

Bone mineral density (BMD) is a biomarker for cumulative exposure to multiple factors including estrogen, calcium, vitamin D and physical activity, which have all been independently associated with colorectal cancer. Furthermore, higher levels of BMD have been inversely associated with colorectal cancer risk, particularly in postmenopausal women. However, no prior studies have examined the potential association between BMD and colorectal adenomas, which are precursor lesions to most colorectal cancers. Therefore, we evaluated the association between BMD, which was measured using a whole body, dual-energy X-ray absorptiometry scan and colorectal adenomas in 167 patients who underwent colonoscopy screening. We found that patients in the highest tertile of total body BMD (>1.294 g/cm(2)) and in the middle tertile (≥1.167 to ≤1.294 g/cm(2)) compared to those with a total body BMD in the lowest tertile (<1.167 g/cm(2)) had a lower risk of colorectal adenomas (highest vs. lowest tertile: OR = 0.29 (0.10-0.84); middle vs. lowest tertile: OR=0.26 (0.08-0.80); p-trend=0.02). Stratification by gender revealed that this association was more pronounced in women (highest (>1.280 g/cm(2)) vs. lowest (<1.130 g/cm(2)) tertile: OR=0.08 (0.01-0.70); middle (≥1.130 to ≤1.280 g/cm(2)) vs. lowest tertile: OR=0.15 (0.04-0.94); p-trend=0.02) even after excluding hormone replacement therapy users (highest (>1.295 g/cm(2)) and middle (≥1.132 to ≤1.295 g/cm(2)) vs. lowest (<1.132 g/cm(2)) tertile: OR=0.17 (0.03-0.97); p-trend=0.04). Our results show, for the first time, that BMD is inversely associated with colorectal adenomas, particularly in women. Although additional larger, prospective studies are needed, our results suggest that BMD may be a biomarker for colorectal cancer precursor lesions.

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.

Recurrence and surveillance of colorectal adenoma after polypectomy in a southern Chinese population

BACKGROUND AND AIM

Repeat colonoscopy is often performed within a short time after polypectomy due to the fear that colorectal adenomas were missed during the initial colonoscopy or that new adenomas have developed. The aim of this study was to estimate the actual recurrence rate of adenoma and its association with the length of the surveillance interval after polypectomy in a southern Chinese population.

METHODS

A total of 1,356 patients undergoing endoscopic polypectomy and completing three or more surveillence colonoscopies between 1976 and 2007 were retrospectively analyzed. The recurrence rates of adenoma and advanced adenoma and surveillance intervals after polypectomy were identified based on the features of adenomas detected on initial colonoscopy.

RESULTS

The recurrence rates of advanced adenoma in patients with non-advanced adenoma on the initial colonoscopy were 0.9, 3.9, 5.8, and 29.2% during surveillance intervals of 1-3, 3-5, 5-10, and 10-20 years post-initial colonoscopy; for patients with advanced adenoma on the initial colonoscopy, the recurrence rates were 3.8, 13.1, 34.7, and 52.0% during the same surveillance intervals, respectively. Older age (p < 0.05 for trend) and male sex [hazard ratio (HR) 2.11, 95% confidence interval (CI) 1.27-3.53] were significantly associated with recurrence for advanced adenoma, as were the size and number of baseline adenoma (p < 0.05 for trend), tubulovillous, villous adenoma (HR 2.57, 95% CI 1.24-5.32), and high-grade dysplasia (HR 1.61, 95% CI 1.07-2.42). When 5% of patients had recurring advanced adenoma, the surveillance interval was estimated to be 6.9 (95% CI 6.3-12.2) years in the low-risk group and 3.0 (95% CI 2.7-3.2) years in the high-risk group.

CONCLUSIONS

Among our patient group, the recurrence of advanced adenoma after polypectomy increased with the length of the surveillance interval. Based on our results, a 3-year follow-up of patients after polypectomy could be effective in preventing the recurrence of advanced adenoma in high-risk patients.

Intestinal tumours, colonic butyrate and sleep in exercised Min mice

There is strong epidemiological evidence that more physical activity is associated with reduced risk of colon cancer, but the amount or type of activity necessary to invoke this protection is disputed, and the mechanism that is responsible has not been elucidated. The present study compared the effects of two contrasting exercise regimens on intestinal tumourigenesis in Min mice, and investigated two novel mechanistic factors: colonic butyrate and sleep. From 5 weeks of age, Min mice were exercised by running on a treadmill (TR; < or = 21 m/min, 30-60 min/d, 5 d/week, < or = 12 weeks). Additional groups of mice were provided with an exercise wheel (WH) or no exercise (CON). Mice had free access to a Western-style, high-fat diet. WH mice ran 3.97 km (females) and 1.92 km (males) daily (P = 0.002). There were no differences in body weight gain or body composition between treatment groups. Treadmill running reduced the numbers of larger ( > or = 2 mm diameter) tumours (P = 0.042), and tended to reduce tumour multiplicity in the colon (P = 0.049). TR mice had a higher molar proportion of butyrate in colonic digesta than CON mice (P = 0.030), and when treatment groups were combined, there was a weak negative correlation (r - 0.174, P = 0.061) between butyrate molar proportion and total tumour number. In a subset of animals in which non-exercise physical activity was monitored, there were strong positive correlations between sleep duration and both tumour multiplicity (P < 0.001) and tumour burden (P = 0.001). More studies of the effects of sleep and of colonic butyrate in mediating the effects of physical activity on intestinal tumourigenesis are warranted.

Physical activity and gastrointestinal cancer prevention

Colorectal cancer is the third most common cancer globally and is a leading cause of cancer death. Gastric cancer contributes significantly to the global cancer burden, particularly in low- and middle-income countries. We reviewed the literature for studies on physical activity or exercise and colon, rectal, and gastric cancers as well as colonic adenomatous polyps. We identified 52 studies of colon cancer, 31 studies of rectal cancer, 23 studies of colon polyps, and 16 studies of gastric cancer. Of the 52 studies of physical activity and colon cancer, 37 found a statistically significant association between increased levels of physical activity and decreased colon cancer risk in at least one comparison. Accumulated evidence suggests that physical activity is associated with a 25% reduction in colon cancer risk. In line with previous reports, we found no indication that the association was more pronounced for occupational versus recreational physical activity, with both resulting in a risk reduction of about 22%. Evidence for other domains of physical activity (i.e., transportation or household physical activity) is limited. Evidence is emerging that individuals who are consistently active across the lifetime may obtain greater risk reductions than those who are only active in recent years. Despite consistent associations with colon cancer, evidence is more limited though suggestive that physical activity reduces risk of colon adenomas or adenoma recurrence. There is clear evidence that physical activity is not associated with rectal or gastric cancers.

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Dietary fatty acids and recurrence of colorectal adenomas in a European intervention trial

Epidemiological studies have provided inconsistent data about the role of dietary fatty acids in colorectal cancer, and few studies have addressed their role in colorectal adenoma. The aim of the study was to assess the risk of overall adenoma recurrence associated with dietary consumption of total fat, subtypes of fat, and specific fatty acids (oleic acid, linoleic acid, alpha-linolenic acid). The study sample was composed of 523 patients with confirmed adenomas at the index colonoscopy, 35 to 75 yr old, who completed the European fiber-calcium intervention trial and had an initial dietary assessment using a qualitative and quantitative food questionnaire. The overall 3-yr recurrence rate was 22.6% (118 out of 523 patients). There were no significant associations between overall adenoma recurrence and either total fat, subtypes of fat, or specific fatty acids. However, polyunsaturated fatty acids and linoleic acid were both moderately but significantly associated with distal and multiple recurrence. No significant associations were observed with recurrence of proximal or advanced adenomas. Our findings do not support the hypothesis of strong associations between dietary fatty acids and recurrence of colorectal adenomas. The hypothesis of a differential role of specific fatty acids according to colorectal subsites deserves further investigation.

Modifiable risk factors for colorectal neoplasms and hyperplastic polyps

PURPOSE

Obesity, smoking and alcohol are modifiable putative risk factors for colorectal neoplasms (CRN) and hyperplastic polyps (HP). The aim of this study was to evaluate the strength of association between these modifiable risk factors and colorectal polyps.

METHODS

These risk factors were assessed by using a questionnaire completed by the patient prior to colonoscopy. Eight hundred-seventy consecutive patients satisfying inclusion criteria who had undergone a complete colonoscopy were divided into 4 groups: CRN (n=194), HP (n=132), CRN and HP (n=42) and control (neither CRN nor HP; n=586). Multiple logistic regression was performed.

RESULTS

The ORs [95%CI] of both CRN and HP for incremental body mass index expressed in 2 categories (>or=22, >or=25) were 2.12 [1.00, 4.50] and 1.41 [0.53, 3.77], respectively. The ORs [95%CI] of CRN and HP for heavy smoking of over 20 pack-years were 1.66 [1.05, 2.64] and 1.67 [1.01, 2.77], respectively. The ORs of CRN and HP for habitual alcohol drinking (median ethanol intake 32 g/day and interquartile range 18-40 g/day) were 1.31 [0.86, 1.98] and 1.91 [1.06, 3.47], respectively. CRN and HP were correlated with each other (p=0.0043, chi-square test). Aging was a significant risk factor for all three groups of colorectal polyps.

CONCLUSION

These findings are especially important since smoking and alcohol consumption are modifiable risk factors. Heavy smokers should be encouraged to quit to reduce their risk of CRN and HP. Habitual drinkers should be warned of the risk of HP. HP can be a marker of coincidence of CRN.

Gastrointestinal endoscopy nurse experience and polyp detection during screening colonoscopy

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Factors that increase risk of colon polyps

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

Clinical and molecular mechanism of the relationship between obesity and colorectal adenoma

AIM: To investigate the relationship between obesity and the colorectal precancerous lesion-adenoma, and to further investigate relationship between obesity and colon cancer and its prevention and treatment.

METHODS: A total of 539 subjects who underwent colonoscopy in Tongji Hospital from December 2006 to December 2007 were selected, and divided into the adenoma group (n = 250) and the control group (n = 289). Body height, weight, waist and hip circumference were measured, respectively. All data were analyzed using logistic multi-factors regression. Four adenomatous tissues, pathologically-confirmed as tubular adenoma or tubulovillous adenoma, 2 with BMI > 24, WC > 85 cm, and the others with BMI < 24, WC < 85 cm, were selected from adenoma group, and used to screen the differentially expressed gene by Oligo Signal Transduction Pathway Microarray.

RESULTS: Obesity (by using BMI cut-offs) (ORadj = 2.48, 95% CI = 1.19-5.20, P = 0.016) and abdominal adiposity (by using WC cut-offs) (ORadj = 1.75, 95% CI = 1.15-2.66, P = 0.009) were significantly associated with an increased risk of colorectal adenomas, especially in men(ORadj = 4.10 and 1.70, 95% CI = 1.26-13.31 and 1.00-2.88, P = 0.019 and 0.019, respectively), but there was no association in overweight group. Abdominal adiposity based on WHR showed no significant difference. Genomic hybridization showed 23 differentially expressed genes between the two groups. Among them, there were 6 genes up-regulated in BMI > 24 group, and 17 genes down-regulated in BMI < 24 group. Foxa2 was up-regulated, and IL-8 and Leptin were down-regulated.

CONCLUSION: Obesity or abdominal adiposity is positively associated with colorectal adenomas; the risk is highly increased in men. It is presumed that there are several abnormally expressed factors in the colorectal adenomous tissues of obesity.

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.

Sporadic and syndromic hyperplastic polyps and serrated adenomas of the colon: classification, molecular genetics, natural history, and clinical management

There is now strong evidence for an alternative pathway of colorectal carcinogenesis implicating hyperplastic polyps and serrated adenomas. This article briefly reviews the evidence for this serrated pathway, provides diagnostic criteria for clinically significant hyperplastic polyps and allied serrated polyps, and suggests how this information may be translated into safe, effective guidelines for colonoscopy-based colon cancer prevention. Consideration also is given to the definition and management of hyperplastic polyposis syndrome. The currently proposed management plan for serrated polyps is tentative because of incomplete knowledge of the nature and behavior of these polyps. This article highlights key areas warranting further research.

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

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

Association between body size and colorectal adenoma recurrence

BACKGROUND & AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Change in body size and the risk of colorectal adenomas

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

Prevention and early detection of colorectal cancer--new horizons

Colorectal cancer is potentially one of the most preventable malignancies. Nutritional awareness (low fat, low red meat, high fruits and vegetables) and regular physical activity have major potential for primary prevention of this malignancy, while early detection technologies have the potential of both influencing mortality from colorectal cancer as well as enhancing primary prevention through detection and removal of lesions that could potentially develop into cancer. While the potential for prevention is large, its materialization is far from being optimal. The large-scale lifestyle changes in the population necessary to reduce colorectal cancer rates are hard to achieve, and most of the early detection technologies are either invasive or otherwise nonappealing to the population. Thus, without abandoning the proven prevention methods, new avenues need to be investigated to deal with this malignancy, which carries both high morbidity and high mortality. Such new avenues can now be followed, both in prevention and detection. Chemoprevention, or the use of medications to prevent disease, has now been extensively explored in colorectal cancer. Some of these interventions, such as supplemental fibers, have failed to demonstrate the anticipated effect, while others such as calcium supplementation have been shown to reduce formation of premalignant lesions, polyps, or adenomas. Data accumulating in recent years have suggested that aspirin, nonsteroidal anti-inflammatory drugs, and selective COX-II inhibitors all have a potential to reduce both colorectal cancer and colorectal adenomas. Issues of safety and therapeutic indexes have recently come up as barriers to the use of COX-II inhibitors, and have again drawn attention to aspirin as a potential drug of choice. Association studies have also shown a major potential role for statins in colorectal cancer prevention. New methodologies in cancer detection involve the introduction of colonography or virtual colonoscopy, and the development of methods of detection of genetic somatic mutations in feces or peripheral blood. While radiological techniques currently avoid the need for premedication and are less invasive, they currently still require similar gut cleansing to colonoscopy, can also lead to perforation, are costly, and carry a non-negligible exposure to radiation. Genetic analysis of the stool for mutations in tumor cells is evolving as a promising technique, struggling to achieve both high sensitivity and high specificity with the right combination of mutations sought. With all of these developments taking place, the near future will undoubtedly bring about the expected reduction in colorectal cancer mortality.

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.