Body mass index and colon cancer screening: a systematic review and meta-analysis

Obesity and cancer stem cells: Roles in cancer initiation, progression and therapy resistance

Obesity, the global pandemic since industrialization, is the number one lifestyle-related risk factor for premature death, which increases the incidence and mortality of various diseases and conditions, including cancer. In recent years, the theory of cancer stem cells (CSCs), which have the capacity for self-renewal, metastasis and treatment resistance, has been bolstered by increasing evidence. However, research on how obesity affects CSCs to facilitate cancer initiation, progression and therapy resistance is still in its infancy, although evidence has already begun to accumulate. Regarding the ever-increasing burden of obesity and obesity-related cancer, it is pertinent to summarize evidence about the effects of obesity on CSCs, as elucidating these effects will contribute to the improvement in the management of obesity-related cancers. In this review, we discuss the association between obesity and CSCs, with a particular focus on how obesity promotes cancer initiation, progression and therapy resistance through CSCs and the mechanisms underlying these effects. In addition, the prospect of preventing cancer and targeting the mechanisms linking obesity and CSCs to reduce cancer risk or to improve the survival of patients with cancer is considered.

Body Image Perception and the Effect of Different Educational Programs on Embarrassment in Patients Undergoing Colonoscopy

PURPOSE

Colonoscopy is recognized as a safe and effective tool for detecting colorectal cancer. However, patients may experience discomfort and embarrassment arising from their body image, with the prejudice that health care professionals will have negative thoughts about their bodies. This study was carried out to determine the effect of the perception of body image and education given with different educational programs on the feeling of embarrassment in patients who were scheduled to undergo colonoscopy.

DESIGN

Quasi-experimental study with pre-test, post-test.

METHODS

The population of this quasi -experimental study with pre-test, post-test, and experimental groups consisted of 184 patients who underwent colonoscopy for the first time at the endoscopy department of a university hospital.

FINDINGS

No statistically significant difference in the mean Colonoscopy Embarrassment Scale (CES) pre-test scores was found between the groups (P > .05). The mean CES post-test scores of the video group were lower than those of the other groups, with a statistically significant difference (P < .05). Comparing the intragroup CES pre-test and post-test mean scores, the mean CES post-test scores were found to be lower in all three groups, with a statistically significant difference between the groups (P < .05). Although a statistically weak negative correlation was found between the body image mean scores and the pre-test CES mean scores of the booklet and video groups, no correlation was observed in the control group.

CONCLUSIONS

The body image perception was found to affect the sense of embarrassment in patients undergoing colonoscopy, and the mean embarrassment scores decreased with planned training programs.

Lower Utilization of Colorectal Cancer Screening Among Vegetarians, Adventist Health Study-2

This study aims to examine lifestyle predictors of the utilization of colorectal cancer screening. Using modified Poisson regression, we studied self-reported colorectal cancer screening utilization (colonoscopy or fecal occult blood test) with various dietary and lifestyle characteristics among 33,922 subjects aged 51 + years in the Adventist Health Study-2, a large population-based prospective cohort study. According to the multivariable-adjusted models, vegetarians were less likely to report screening: vegans, prevalence ratio (PR) = 0.80 (95% confidence interval 0.77-0.83); lacto-ovo-vegetarians (0.95 [0.93-0.97]); and semi-vegetarians (0.97 [0.94-0.99]) compared to non-vegetarians. Blacks were more likely than non-Blacks to be screened (1.04 [1.02-1.06]) and males were less likely (0.93 [0.92-0.95]) to utilize the screening tests. Older subjects were more likely to be screened, and unmarried and divorced/widowed subjects were less likely to screen. Education, personal income, and BMI were positively associated with screening, with p-value for trend < 0.001 for all three variables. A family history of colorectal cancer was associated with higher screening prevalence (1.15 [1.12-1.17]). Our stratified analyses on race and gender with dietary patterns showed non-Hispanic White vegans (PR = 0.77 [0.74-0.81]) and male vegans (PR = 0.76 [0.72-0.81]) were least likely compliant with colorectal cancer screening (p = 0.009 and p = 0.04, respectively). Vegans may believe that their personal risk for colorectal cancer is low due to their healthy lifestyle, resulting in lack of compliance to colorectal cancer screening. It remains to be seen whether vegans in AHS-2 also experience higher incidence of colorectal cancer or are diagnosed at a later stage.

Preventive Health Screening in Veterans Undergoing Bariatric Surgery

INTRODUCTION

Individuals with obesity are vulnerable to low rates of preventive health screening. Veterans with obesity seeking bariatric surgery are also hypothesized to have gaps in preventive health screening. Evaluation in a multidisciplinary bariatric surgery clinic is a point of interaction with the healthcare system that could facilitate improvements in screening.

METHODS

This is a retrospective cohort study of 381 consecutive patients undergoing bariatric surgery at a Veterans Affairs Hospital from January 2010 to October 2021. Age- and sex-appropriate health screening rates were determined at initial referral to a multidisciplinary bariatric surgery clinic and at the time of surgery. Rates of guideline concordance at both time points were compared using McNemar's test. Univariate and multivariate analyses were performed to identify the risk factors for nonconcordance.

RESULTS

Concordance with all recommended screening was low at initial referral and significantly improved by time of surgery (39.1%‒63.8%; p<0.001). Screening rates significantly improved for HIV (p<0.001), cervical cancer (p=0.03), and colon cancer (p<0.001). Increases in BMI (p=0.005) and the number of indicated screening tests (p=0.029) were associated with reduced odds of concordance at initial referral. Smoking history (p=0.012) and increasing distance to the nearest Veterans Affairs Medical Center (p=0.039) were associated with reduced odds of change from nonconcordance at initial referral to concordance at the time of surgery.

CONCLUSIONS

Rates of preventive health screening in Veterans with obesity are low. A multidisciplinary bariatric surgery clinic is an opportunity to improve preventive health screening in Veterans referred for bariatric surgery.

FABP4 in obesity-associated carcinogenesis: Novel insights into mechanisms and therapeutic implications

The increasing prevalence of obesity worldwide is associated with an increased risk of various diseases, including multiple metabolic diseases, cardiovascular diseases, and malignant tumors. Fatty acid binding proteins (FABPs) are members of the adipokine family of multifunctional proteins that are related to fatty acid metabolism and are divided into 12 types according to their tissue origin. FABP4 is mainly secreted by adipocytes and macrophages. Under obesity, the synthesis of FABP4 increases, and the FABP4 content is higher not only in tissues but also in the blood, which promotes the occurrence and development of various cancers. Here, we comprehensively investigated obesity epidemiology and the biological mechanisms associated with the functions of FABP4 that may explain this effect. In this review, we explore the molecular mechanisms by which FABP4 promotes carcinoma development and the interaction between fat and cancer cells in obese circumstances here. This review leads us to understand how FABP4 signaling is involved in obesity-associated tumors, which could increase the potential for advancing novel therapeutic strategies and molecular targets for the systematic treatment of malignant tumors.

Review article: obesity and colorectal cancer

BACKGROUND

Obesity is a growing global public health problem. More than half the European and North American population is overweight or obese. Colon and rectum cancers are still the second leading cause of cancer death worldwide, and epidemiological data support an association between obesity and colorectal cancers (CRCs).

AIM

To review the literature on CRC epidemiology in obese subjects, assessing the effects of obesity, including childhood or maternal obesity, on CRC, diagnosis, management, and prognosis, and discussing targeted prophylactic measures.

METHOD

We searched PubMed for obesity/overweight/metabolic syndrome and CRC. Other key words included 'staging', 'screening', 'treatment', 'weight loss', 'bariatric surgery' and 'chemotherapy'.

RESULTS

In Europe, about 11% of CRCs are attributed to overweight and obesity. Epidemiological data suggest that obesity is associated with a 30%-70% increased risk of colon cancer in men, the association being less consistent in women. Visceral fat or abdominal obesity seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m² increase in body mass index confers more risk (hazard ratio 1.03). Obesity might increase the likelihood of recurrence or mortality of the primary cancer and may affect initial management, including accurate staging. The risk maybe confounded by different factors, including lower adherence to organised CRC screening programmes. It is unclear whether bariatric surgery helps reduce rectal cancer risk.

CONCLUSIONS

Despite a growing body of evidence linking obesity to CRC, many questions remain unanswered, including whether we should screen patients with obesity earlier or propose prophylactic bariatric surgery for certain patients with obesity.

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

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

FABP4 promotes invasion and metastasis of colon cancer by regulating fatty acid transport

Background

The prognosis of colon cancer is poor for metastasis, while the mechanism, especially adipocytes related, is not yet clear. The purpose of this study is to determine the effects of fatty acid binding protein 4 (FABP4), a transporter for lipids, on colon cancer progression.

Methods

The distribution of lipids and FABP4 was tested in the colon cancer tissues and adjacent normal tissues, and their relationship was also verified in vitro. Experiments about cellular invasion, migration and proliferation were performed to detect the impacts of FABP4 on the biological behaviors of colon cancer, and the positive results were checked in vivo. Meanwhile, the regulatory role of FABP4 in the energy and lipid metabolism was evaluated by the levels of triglyceride, ATP, LDH, glycerol and NEFA. At last, GO and KEGG analysis based on FABP4 overexpressed cells was performed, and the AKT pathway and epithelial-mesenchymal transition (EMT)-related proteins were determined by Western blot.

Results

Higher accumulation of lipids and stronger FABP4 transcription were observed in colon cancer tissues. Having been incubated with adipose tissue extract and overexpressed FABP4, colon cancer cells demonstrated enhanced lipid accumulation. In functional experiments, co-culture with adipose tissue extract significantly enhanced the invasion and migration of colon cancer cells, as well as the energy and lipid metabolism, and all these processes were reversed by FABP4 inhibitor. In addition, the metastasis of FABP4-overexpressed colon cancer cells was also significantly enhanced in vitro and in vivo. In terms of mechanism, the bioinformatics analysis showed that FABP4 was enriched in 11 pathways related to metabolic processes in FABP4 overexpressed cells. Finally, FABP4 overexpression improved EMT progression of colon cancer, as evidenced by the upregulation of Snail, MMP-2 and MMP-9, the downregulation of E-cadherin. The expression of p-Akt was also elevated.

Conclusion

FABP4 overexpression could increase FAs transport to enhance energy and lipid metabolism, and activate AKT pathway and EMT to promote the migration and invasion of colon cancer cells.

Colorectal cancer risk based on extended family history and body mass index

Family history and body mass index (BMI) are well-known risk factors for colorectal cancer (CRC), however, their joint effects are not well described. Using linked data for genealogy, self-reported height and weight from driver's licenses, and the Utah Surveillance, Epidemiology, and End-Results cancer registry, we found that an increasing number of first-degree relatives (FDR) with CRC is associated with higher standardized incidence ratio (SIR) for overweight/obese probands but not for under/normal weight probands. For probands with two CRC-affected FDRs, the SIR = 1.91 (95% CI [0.52, 4.89]) for under/normal weight probands and SIR = 4.31 (95% CI [2.46, 7.00]) for overweight/obese probands. In the absence of CRC-affected FDRs, any number of CRC-affected SDRs did not significantly increase CRC risk for under/normal weight probands, but for overweight/obese probands with at least three CRC-affected SDRs the SIR = 2.68 (95% CI [1.29, 4.93]). In the absence of CRC-affected FDRs and SDRs, any number of CRC-affected third-degree relatives (TDRs) did not increase risk in under/normal weight probands, but significantly elevated risk for overweight/obese probands with at least two CRC-affected TDRs was observed; SIR = 1.32 (95% CI [1.04, 1.65]). For nonsyndromic CRC, maximum midlife BMI affects risk based on family history and should be taken into account for CRC risk communication when possible.

A Comparative Study Evaluating the Incidence of Colorectal Neoplasia(s) in Candidates for Bariatric Surgery by Screening Colonoscopy, 40-49 Versus 50-65 Years Old: a Preliminary Study

INTRODUCTION

Obesity and metabolic syndrome (MetS) are associated with colorectal neoplasia (CRN) and carcinoma (CRC). Whether such subjects must undergo screening colonoscopy (SC) earlier, is unknown. Incidences of CRNs in 40-49- versus 50-65-year-old bariatric patients were compared by SC. No prospective data on SC is available in morbidly obese/MetS.

MATERIAL AND METHODS

Surgical weight loss candidates over 39 years of age, asymptomatic, and average-risk for CRC offered SC. Those giving written informed consent were enrolled. Colonoscopies were done by the same surgeon. Smoking/drinking history, fasting blood glucose (FBG), insulin, C-peptide, triglyceride, high density lipoprotein, vitamin D, HbA1c, and insulin resistance parameters were recorded. CRN rate and the distribution of variables in patients 40-49 years of age were compared with 50-65. Student's t and Chi-square tests were used as appropriate. P < 0.05 was regarded as statistically significant.

RESULTS

Among 168 SCs, 47 had CRNs (27.9%). Including carcinoma, 15 had an advanced CRN (aCRN) (8.9% aCRN and 0.6% CRC). CRN rate was 35.6% in ≥ 50 years old whereas 22.1% in 40-49 (p = 0.053). aCRN rates (8.4% in 40-49 versus 9.6% in 50-65) were similar (p = 0.792). Metabolic parameters and smoking-drinking history were equally distributed between the groups except FBG and HbA1c as their mean levels were slightly higher in the 50-65 age group (p < 0.05).

CONCLUSIONS

Presented results warrant routine SC in the 40-49-year-old morbidly obese and/or MetS patient population with average risk, and in aged > 50, it certainly must be enforced and included in the preoperative check-list if not done before.

Obesity and gastrointestinal cancer: the interrelationship of adipose and tumour microenvironments

Increasing recognition of an association between obesity and many cancer types exists, but how the myriad of local and systemic effects of obesity affect key cellular and non-cellular processes within the tumour microenvironment (TME) relevant to carcinogenesis, tumour progression and response to therapies remains poorly understood. The TME is a complex cellular environment in which the tumour exists along with blood vessels, immune cells, fibroblasts, bone marrow-derived inflammatory cells, signalling molecules and the extracellular matrix. Obesity, in particular visceral obesity, might fuel the dysregulation of key pathways relevant to both the adipose microenvironment and the TME, which interact to promote carcinogenesis in at-risk epithelium. The tumour-promoting effects of obesity can occur at the local level as well as systemically via circulating inflammatory, growth factor and metabolic mediators associated with adipose tissue inflammation, as well as paracrine and autocrine effects. This Review explores key pathways linking visceral obesity and gastrointestinal cancer, including inflammation, hypoxia, altered stromal and immune cell function, energy metabolism and angiogenesis.

National Disparities in Colorectal Cancer Screening Among Obese Adults

INTRODUCTION

Obesity is a major risk factor for colorectal cancer (CRC), particularly among men. The purpose of this study was to characterize the prevalence of guideline-adherent CRC screening among obese adults using nationally representative data, assess trends in screening strategies, and identify obesity-specific screening barriers.

METHODS

Data from 8,550 respondents aged 50-75 years in the 2010 National Health Interview Survey, representing >70 million adults, were analyzed in 2015 using multivariable logistic regression. Prevalence of guideline-adherent CRC screening, endoscopic versus fecal occult blood test screening, and reasons for non-adherence were compared across BMI categories.

RESULTS

Obese class III men (BMI ≥40), compared with normal-weight men, were significantly less likely to be adherent to screening guidelines (38.7% vs 55.8%, AOR=0.35, 95% CI=0.17, 0.75); less likely to have used an endoscopic test (36.7% vs 53.0%, AOR=0.37, 95% CI=0.18, 0.79); and had a trend toward lower fecal occult blood test use (4.2% vs 8.9%, AOR=0.42, 95% CI=0.14, 1.27). Among women, odds of guideline adherence and use of different screening modalities were similar across all BMI categories. Reasons for non-adherence differed by gender and BMI; lacking a physician screening recommendation differed significantly among men (29.7% obese class III vs 15.4% non-obese, p=0.04), and pain/embarrassment differed significantly among women (11.6% obese class III vs 2.6% non-obese, p=0.002).

CONCLUSIONS

Despite elevated risk, severely obese men were significantly under-screened for CRC. Addressing the unique screening barriers of obese adults may promote screening uptake and lessen disparities among the vulnerable populations most affected by obesity.

NCAPH plays important roles in human colon cancer

Colon cancer (CC) is one of the major malignancies worldwide, whose pathogenesis is complex and requires the accumulated alteration of multiple genes and signaling pathways. Condensins are multi-protein complexes that play pivotal roles in chromosome assembly and segregation during mitosis, meiosis and even tumorigenesis. Using tissue microarrays by immunohistochemistry and hematoxylin–eosin staining, we found that non-SMC condensin I complex subunit H (NCAPH) in colon cancerous tissues was higher than that in all corresponding adjacent non-cancerous tissues. We then characterized the exact function of the NCAPH in CC. We provided evidences showing that NCAPH is highly expressed in colorectal cancer cell lines comparing with normal human colonic epithelial cells, and identified many NCAPH mutations in CC patients. We found that depletion of NCAPH inhibits CC cell proliferation, migration in vitro and xenograft tumor formation in vivo. Furthermore, NCAPH knockdown promotes cell apoptosis and cell cycle arrest at G2/M phase. Interestingly, the NCAPH high expression in tumor tissues of colon patients had a significantly better prognosis and survival rate than low-expression patients, suggesting that NCAPH high expression promotes colonic cancerous cell proliferation; on the other hand, it may also sensitize these cells responding to chemo- or radio-therapies. Collectively, these findings reveal an important role of NCAPH in CC, indicating that NCAPH could be used as a new therapeutic target in future.

Time to Colonoscopy after Positive Fecal Blood Test in Four U.S. Health Care Systems

BACKGROUND

To reduce colorectal cancer mortality, positive fecal blood tests must be followed by colonoscopy.

METHODS

We identified 62,384 individuals ages 50 to 89 years with a positive fecal blood test between January 1, 2011 and December 31, 2012 in four health care systems within the Population-Based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium. We estimated the probability of follow-up colonoscopy and 95% confidence intervals (CI) using the Kaplan-Meier method. Overall differences in cumulative incidence of follow-up across health care systems were assessed with the log-rank test. HRs and 95% CIs were estimated from multivariate Cox proportional hazards models.

RESULTS

Most patients who received a colonoscopy did so within 6 months of their positive fecal blood test, although follow-up rates varied across health care systems (P <0.001). Median days to colonoscopy ranged from 41 (95% CI, 40-41) to 174 (95% CI, 123-343); percent followed-up by 12 months ranged from 58.1% (95% CI, 51.6%-63.7%) to 83.8% (95% CI, 83.4%-84.3%) and differences across health care systems were also observed at 1, 2, 3, and 6 months. Increasing age and comorbidity score were associated with lower follow-up rates.

CONCLUSION

Individual characteristics and health care system were associated with colonoscopy after positive fecal blood tests. Patterns were consistent across health care systems, but proportions of patients receiving follow-up varied. These findings suggest that there is room to improve follow-up of positive colorectal cancer screening tests.

IMPACT

Understanding the timing of colonoscopy after positive fecal blood tests and characteristics associated with lack of follow-up may inform future efforts to improve follow-up.

Major Protein of Carcinoembryonic Antigen Gene Family - CD66c, A Novel Marker in Colon Carcinoma

INTRODUCTION

In view of rising trend of the incidence of colorectal carcinoma in the Indian population due to adoption of western lifestyles and behaviours, we investigated the expression of the new emerging stem cell biomarker, CD66c in colorectal carcinoma of Indian origin.

AIM

To study the expression of CD66c in human colorectal carcinoma and to correlate level of marker expression with tumour staging.

MATERIALS AND METHODS

This hospital based prospective study was conducted on 26 colorectal carcinoma patients in the age group of 20 years to 70 years. Surgically resected tumour specimens along with adjacent normal tissue were collected taking necessary precautions, paraffin embedded sections were prepared and used for histological and immunohistochemical analysis of CD66c.

STATISTICAL ANALYSIS

Descriptive statistical measures like mean, standard deviation, percentage was applied. Other inferential statistical tests like Chi-square, Fisher's-exact test and one-way ANOVA was applied to find out the association of CD66c with different stages. The difference were interpreted as statistically significant when p <0.05.

RESULTS

CD66c showed differential expression with membrane positivity in normal colorectal epithelial cells and cytoplasmic expression in tumour cells. There was significant correlation between CD66c expression and tumour site (p=0.02) with colon carcinoma showing positive expression compared to the rectal carcinoma. There was no significant correlation between CD66c staining and tumour stage (p=0.947). No significant relationship was observed between CD66c expression and other clinicopathologic variables studied such as sex (p=0.552), age (p=0.713) and tumour grade (p=0.263).

CONCLUSION

CD66c can be specifically used for colon carcinoma and may be a novel marker in colon carcinoma stem cell isolation. The quantification of CD66c can be further verified by flow cytometry and RT-PCR. Further studies can be carried out using CD66c alone or in combination with other markers to develop cancer stem cell directed therapy.

Diabetes and Body Mass Index Are Associated with Neuropathy and Prognosis in Colon Cancer Patients Treated with Capecitabine and Oxaliplatin Adjuvant Chemotherapy

BACKGROUND

There are few background data on the impact of clinical factors on neurotoxicity and prognosis in patients treated with adjuvant capecitabine and oxaliplatin (CAPOX) chemotherapy.

METHODS

102 stage II high-risk and stage III colorectal cancer patients were treated for 6 months with adjuvant CAPOX, then they were followed up. Associations between clinical variables, metabolic syndrome components, smoking and neurotoxicity were evaluated by the x03C7;2 test. The Kaplan-Meier product limit method was applied to graph disease-free survival (DFS). Univariate analysis was done with the log-rank test. Cox's proportional hazards regression was used to analyze the effect of several risk factors on DFS.

RESULTS

Significant associations were found between diabetes (p < 0.001), BMI (p = 0.01) and the occurrence of chronic neurotoxicity. After a median follow-up of 46 months, 14 patients (13.7%) had suffered recurrence. An analysis of the prognostic factors for DFS showed that prognosis is unfavorable for patients with high lymph-nodal involvement (HR: 5.23, p = 0.0007), diabetes (HR: 4.86; p = 0.03) and a BMI ≥25 (HR: 3.69, p = 0.002).

DISCUSSION

Common mediators in diabetes and obesity could be involved in peripheral neuropathy and in stimulating micro-metastases. Further studies are necessary to explain this interesting connection between diabetes, obesity and colon cancer.

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.

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.

Republished: obesity and colorectal cancer

Excess body weight, as defined by the body mass index (BMI), has been associated with several diseases and includes subjects who are overweight (BMI≥25-29.9 kg/m(2)) or obese (BMI≥30 kg/m(2)). Overweight and obesity constitute the fifth leading risk for overall mortality, accounting for at least 2.8 million adult deaths each year. In addition around 11% of colorectal cancer (CRC) cases have been attributed to overweight and obesity in Europe. Epidemiological data suggest that obesity is associated with a 30-70% increased risk of colon cancer in men, whereas the association is less consistent in women. Similar trends exist for colorectal adenoma, although the risk appears lower. Visceral fat, or abdominal obesity, seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m(2) increase in BMI confers additional risk (HR 1.03). Obesity might be associated with worse cancer outcomes, such as recurrence of the primary cancer or mortality. Several factors, including reduced sensitivity to antiangiogenic-therapeutic regimens, might explain these differences. Except for wound infection, obesity has no significant impact on surgical procedures. The underlying mechanisms linking obesity to CRC are still a matter of debate, but metabolic syndrome, insulin resistance and modifications in levels of adipocytokines seem to be of great importance. Other biological factors such as the gut microbita or bile acids are emerging. Many questions still remain unanswered: should preventive strategies specifically target obese patients? Is the risk of cancer great enough to propose prophylactic bariatric surgery in certain patients with obesity?

Patterns of colorectal cancer screening uptake in newly eligible men and women

BACKGROUND

We describe patterns of colorectal cancer screening uptake in a U.S. insured population as individuals become newly eligible for screening at age 50 and assess temporal trends and patient characteristics with screening uptake.

METHODS

We identified a cohort of 81,223 men and women who were members of Group Health and turned 50 years old from 1996 to 2010. We ascertained receipt of colorectal cancer screening within five years. Time to screening was estimated by year of cohort entry using cumulative incidence curves and Cox proportional hazards models-estimated patient characteristics associated with screening uptake.

RESULTS

Stool-based screening tests were the most common, 72% of first screening tests. The proportion of individuals initiating colorectal cancer screening via colonoscopy increased from 8% in 1996 to 1998 to 33% in 2008 to 2010. Patient factors associated with increased colorectal cancer screening were: turning 50 more recently (2008-2010; Ptrend < 0.0001) or Asian race [HR, 1.14; 95% confidence interval (CI), 1.10-1.19]. Patient factors associated with decreased screening were: being a woman (HR, 0.70; 95% CI, 0.68-0.72), Native American (HR, 0.68; 95% CI, 0.60-0.78), or Pacific Islander race (HR, 0.82; 95% CI, 0.72-0.95), and having prevalent diabetes (HR, 0.78; 95% CI, 0.75-0.82) and higher body mass index (Ptrend < 0.0001).

CONCLUSIONS

Patient characteristics associated with initiation of colorectal cancer screening in a newly eligible population are similar to characteristics associated with overall screening participation in all age-eligible adults. Our results identify patient populations to target in outreach programs.

IMPACT

Disparities in receipt of colorectal cancer screening are evident from onset of an age-eligible cohort, identifying key groups for future interventions for screening.

Body mass index and cancer screening: Findings from the English Longitudinal Study of Ageing

Objectives

Obesity is associated with an increased cancer incidence and mortality and therefore cancer screening is particularly important for obese individuals. However, some US studies find lower screening uptake in this group. This study explored whether rates of breast and colorectal screening in England are lower for obese than healthy weight individuals.

Setting

Data were from the English Longitudinal Study of Ageing (ELSA).

Methods

We analysed data from adults who were eligible to have been invited to the UK national screening programmes for breast or colorectal cancer (CRC) in the last five years, and had been given the screening module in Wave 5 of ELSA (N = 1804 for CRC screening, N = 2401 for breast cancer screening). Weight and height were measured by a nurse at Wave 4 (two years earlier). Logistic regression was used to calculate the odds of breast and CRC screening (ever) for participants in higher weight categories (Body Mass Index [BMI] ≥ 25) compared with healthy weight individuals (BMI <25), controlling for socio-demographic variables.

Results

Of ELSA participants, 63% reported CRC screening, and 92% of the women reported breast cancer screening. Obesity was associated with lower CRC screening, but effects were strongest for class III obesity (BMI ≥40) (45% screened; OR = 0.48, 95% CI = 0.32–0.93, P = .029). There was no association between weight status and breast cancer screening.

Conclusion

Severe obesity appears to be a deterrent to CRC screening but not breast cancer screening. Targeted interventions may be required to promote CRC screening uptake in this group, which already has a heightened risk as a consequence of weight.

Screening for prostate cancer: are digital rectal examinations being performed?

OBJECTIVE

Prostate cancer is common and prostate cancer screening is controversial; this retrospective observational study was conducted to determine the prevalence of digital rectal examination (DRE) in those in whom a prostate-specific antigen (PSA) test was performed.

METHODS

A manual review was performed of the electronic medical record for male veterans in the VA Connecticut Healthcare System without a history of known prostate cancer aged between 50 and 74 years who underwent PSA testing.

MAIN OUTCOMES

Documentation of DRE (or refusal) within 12 months before or after the performance of a PSA test.

RESULTS

Less than half (47.6%) of patients underwent DRE. An additional 6.9% were offered DRE and refused. Although the provider gender was not associated with DRE, resident physicians were less likely to perform DRE than nonresidents; P = 0.01. Patients whose PSA was > 4.0 ng/mL were more likely to undergo DRE than those whose PSA was ≤ 4.0 ng/mL; P = 0.002. Those with body mass index (BMI) > 40 kg/m 2 were less likely to undergo DRE than those with BMI < 30 kg/m 2 ; P = 0.04.

CONCLUSIONS

Screening for prostate cancer remains controversial. We found a low rate of DRE among veterans in whom prostate cancer screening was entertained. Although the provider gender does not seem to influence DRE, resident physicians were less likely to perform DRE than other providers. Our finding that BMI > 40 kg/m 2 is associated with a lower rate of DRE than those with BMI < 30 kg/m 2 is consistent with screening for other cancers and should be explored further.

Colorectal cancer association with metabolic syndrome and its components: a systematic review with meta-analysis

We performed a systematic review and meta-analysis of the empirical evidence on the association of metabolic syndrome and its components with colorectal cancer incidence and mortality. A systematic literature search of multiple electronic databases was conducted and complemented by cross-referencing to identify studies published before 31 October 2012. Every included study was to report risk estimates with 95 % confidence intervals for the association between metabolic syndrome and colorectal cancer (incidence or mortality). Core items of identified studies were independently extracted by two reviewers, and results were summarized by standard methods of meta-analysis. We identified 17 studies, which reported on 49 data sets with 11,462 cancer cases. Metabolic syndrome was associated with an increased risk of colorectal cancer incidence and mortality in both men (RR: 1.33, 95 % CI 1.18-1.50, and 1.36, 1.25-1.48, respectively) and women (RR: 1.41, 1.18-1.70, and 1.16, 1.03-1.30, respectively). The risk estimates changed little depending on type of study (cohort vs non cohort), populations (US, Europe, Asia), cancer site (colon and rectum), or definition of the syndrome. The risk estimates for any single factor of the syndrome were significant for higher values of BMI/waist (RR: 1.19, 95 % CI 1.10-1.28), dysglycemia (RR: 1.29, 1.11-1.49), and higher blood pressure (RR: 1.09, 1.01-1.18). Dysglycemia and/or higher BMI/waist explained most of the risk associated with metabolic syndrome. Metabolic syndrome is associated with an increased risk of colorectal cancer incidence and mortality in both sexes. The risk conveyed by the full syndrome is not superior to the sum of its parts.

Are obese women more likely to participate in a mobile mammography program?

Mobile mammography services are typically offered as a means to increase access and adherence to mammography screenings. As mobile mammography becomes a viable strategy to increase screening, a 3 year study of such a state-wide program in WV found surprisingly high rates of obesity within the study population. Thus, the objectives were to: (1) describe the demographic characteristics and comorbidities of women who utilized the WV program, and (2) determine the association between body mass index (BMI) and personal health and screening history, preventive care and wellness behaviors, nutrition and exercise behaviors, and demographics. Data collected from 1,099 women, age 40 and above, were analyzed using descriptive statistics, bivariate analyses, and a multivariate regression model. The majority (60.4 %) were married, had an income <$25,000 (59.2 %), and had health insurance (53.5 %). Major comorbidities were hypertension (49 %) and high cholesterol (43.9 %). Based on BMI scores, 884 participants were either overweight (26.6 %), mildly obese (27.7 %), moderately obese (15.1 %), or severely obese (11.1 %). Bivariate analyses indicated that increasing BMI was significantly associated with factors such as having hypertension or diabetes, limited daily activities, perceived health, and not smoking or drinking. The regression model was significant (p < 0.001; R2 = 0.425) indicating that women who engaged in preventive care behaviors were less likely to be obese than those who did not. The WV mobile mammography program appeared to attract women who were disproportionately obese and had multiple comorbidities, thus providing a great opportunity for targeted interventions related to improving preventive care and screening behaviors.

Online narratives and peer support for colorectal cancer screening: a pilot randomized trial

BACKGROUND

Delivering personal narratives and peer support for CRC screening in an online weight-loss community could be an efficient approach to engaging individuals at increased risk, because obesity is associated with excess colorectal cancer (CRC) mortality and lower screening rates.

PURPOSE

Evaluate user engagement and impact of narratives and peer support for promoting CRC screening in an online weight-loss community.

DESIGN

Pilot randomized trial.

SETTING/PARTICIPANTS

Members of an online weight-loss community who were not up-to-date with CRC screening were enrolled in the study in 2011.

INTERVENTION

Basic and Enhanced groups (n=153 each) both received education. The Enhanced group also received narratives and peer support for CRC screening in online forums.

MAIN OUTCOME MEASURES

The main measures were user engagement, psychosocial outcomes, and self-report CRC screening at 6 months. Analyses were conducted with (1) the full sample of participants and (2) a minimum dose sample of those who participated in their assigned intervention to a minimum degree. Analyses were completed in 2012.

RESULTS

Participants were mostly female (92%) with a mean age of 56 years. More than 90% in both groups viewed the educational information. Only 57% in the Enhanced group joined the online team. The Enhanced group had greater improvement in motivation for screening than the Basic group at 1 month (p=0.03). In the full sample, there was no difference in CRC screening at 6 months (Enhanced 19% vs Basic 16%, adjusted OR=1.33, 95% CI=0.73, 2.42). In the minimum dose sample, fecal occult blood testing was higher in the Enhanced (14%) vs Basic (7%) group (adjusted OR=2.49, 95% CI=1.01, 6.17).

CONCLUSIONS

Although no between-group differences in CRC screening were seen at 6 months, this study did demonstrate that it is feasible to deploy a narrative and peer support intervention for CRC screening in a randomized trial among members of an online community. However, modifications are needed to improve user engagement.

TRIAL REGISTRATION

This study is registered at ClinicalTrials.gov NCT01411826.

Risk of colonic cancer is not higher in the obese Lep(ob) mouse model compared to lean littermates

Epidemiological data suggest that obesity increases the risk of colorectal cancer in humans. Given that diet-induced obesity mouse models verified the epidemiological data, the present study aimed to determine whether obese C57BL/6J-Lep(ob) male mice (a different obesity in vivo model) were at greater risk of colonic cancer than their lean male littermates. Risk of colonic tumorigenesis was assessed by numbers of aberrant crypts, aberrant crypt foci and colonic tumors. Proliferation of the colonic epithelia was assessed histochemically following administration of BrdU. Availability of the procarcinogen, azoxymethane (AOM) to target tissues was assessed by quantifying via HPLC plasma AOM concentrations during the 60 min period following AOM injection. When obese and lean mice were injected with azoxymethane (AOM) at doses calculated to provide equivalent AOM levels per kg lean body mass, obese animals had significantly fewer aberrant crypts/colon and fewer aberrant crypt foci/colon than the lean animals. Tumors were identified in the colonic mucosa of lean (4 tumors in 14 mice) but not obese (0 tumors in 15 mice) mice. Colonic cell proliferation was not significantly different for obese and lean mice. Because these results were unexpected, plasma AOM concentrations were measured and were found to be lower in the obese than lean mice. When plasma AOM levels were comparable for the lean and obese mice, the Lep(ob) mice continued to have significantly fewer aberrant crypt foci/colon than the lean mice, but differences were not statistically different for aberrant crypts/colon. Interestingly, obese Lep(ob) mice did not exhibit increased risk of colonic cancer as expected. Instead, Lep(ob) mice exhibited equivalent or lower risk of colon cancer when compared to the lean group. These results taken together with in vivo results from diet-induced obesity studies, imply that leptin may be responsible for the increased risk of colon cancer associated with obesity.

Prospective investigation of body mass index, colorectal adenoma, and colorectal cancer in the prostate, lung, colorectal, and ovarian cancer screening trial

PURPOSE

Obesity has consistently been linked to an increased risk of colorectal cancer, particularly among men. Whether body mass index (BMI) differentially influences the risk across the stages of colorectal cancer development remains unclear. We evaluated the associations of BMI with colorectal adenoma incidence, adenoma recurrence, and cancer in the context of a large screening trial, in which cases and controls had an equal chance for disease detection.

METHODS

We prospectively evaluated the association between baseline BMI and the risk of incident distal adenoma (1,213 cases), recurrent adenoma (752 cases), and incident colorectal cancer (966 cases) among men and women, ages 55 to 74 years, randomly assigned to receive flexible sigmoidoscopy screening as part of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. We calculated odds ratios (ORs) and 95% CIs for adenoma incidence and recurrence, and hazard ratios (HRs) and 95% CIs for colorectal cancer incidence, using multivariable-adjusted models.

RESULTS

Compared with normal-weight men (18.5 to 24.9 kg/m(2)), obese men (≥ 30 kg/m(2)) had significantly higher risk of incident adenoma (OR, 1.32; 95% CI, 1.06 to 1.65) and colorectal cancer (HR, 1.48; 95% CI, 1.16 to 1.89) and a borderline increased risk of recurrent adenoma (OR, 1.50; 95% CI, 0.98 to 2.30). No associations were observed for either adenoma or cancer in women.

CONCLUSION

Data from this large prospective study suggest that obesity is important throughout the natural history of colorectal cancer, at least in men, and colorectal cancer prevention efforts should encourage the achievement and maintenance of a healthy body weight in addition to regular screenings.

Editorial: Body mass index and colorectal adenomas

The recent American College of Gastroenterology Guidelines for Colorectal Cancer Screening highlight obese individuals as a high-risk group for colorectal cancer (CRC). In this issue, Okabayashi and colleagues present data from a well-designed and executed meta-analysis demonstrating an increased adenoma risk for a modest increase in body mass index (BMI). Specifically, overweight (BMI≥25) subjects have an increased risk for colorectal adenomas (odds ratio=1.24 (95% confidence interval=1.16-1.33)) as compared with non-overweight subjects. The paper's many strengths include the careful selection of the best studies. These data highlight the importance of screening in obese patients.