The role of obesity in gastrointestinal cancer: evidence and opinion

Comparison of robotic versus laparoscopic surgery for visceral obesity in mid-low rectal cancer: a propensity-matched analysis

Obesity is becoming more and more common, and measuring visceral fat area (VFA) is a useful diagnostic technique for visceral obesity (VO). The purpose of this research is to compare the surgical results of robotic versus laparoscopic rectal surgery, with a focus on assessing the benefits of the latter method for treating both VO and mid-low rectal cancer. Patients receiving laparoscopic or robotic anterior rectal excision at Northern Jiangsu People's Hospital's general surgery department were included in the retrospective analysis. 242 people in all took part in the study; 121 cases were assigned to the robotic surgery (RS) group and another 121 cases to the laparoscopic surgery (LS) group. In comparison to LS, our results show that RS led to a shorter period for the recovery of bowel function (p = 0.03), a shorter hospital stay (p < 0.001), a smaller intraoperative blood loss (p < 0.001), and a shorter time until the commencement of oral intake (p = 0.041). However, there were no statistically significant differences between the two groups in terms of the indices of histopathologic specimens, the proportion of temporary loop ileostomy, and the incidence of early postoperative problems (p > 0.05). When patients with VO undergo surgery for rectal cancer, RS has the added benefit of accelerating patient recovery while producing results that are similar to LS in the near run.

Trends in gastric cancer mortality 2005-2020 in Peru and its geographical areas: A joinpoint regression analysis

BACKGROUND

Gastric cancer (GC) is the leading cause of cancer death in Peru. However, information regarding trends in mortality rates in Peru and its geographical areas in the last few decades is lacking. Our objective was to describe GC mortality rates in Peru between 2005 and 2020.

METHODS

Age standardized mortality rates (ASMR) were calculated per 100,000 person-years using the world SEGI standard population. Joinpoint regression analysis was performed to examine mortality trends. The analysis of the last 5 years was performed for Peru and its geographical areas.

RESULTS

GC mortality rates in 2005 and in 2020 were 13.81 and 10.52, respectively, for men and 11.81 and 8.06, respectively, for women. Between 2016 and 2020, Huanuco and Huancavelica reported the highest mortality rates (≥20 deaths per 100,000). In men, Peru and the highlands region reported significant decreases in GC mortality rates in both sexes for some periods. Coastal region significant decreased by 2.6 % in all periods for women. In both sexes, six provinces reported significant decreases in GC mortality rates.

CONCLUSION

Although GC mortality rates in Peru have declined over the past 16 years. They are still one of the highest in the Latin American and Caribbean region. It is important that the Peruvian State seek to reduce the mortality of this disease through prevention efforts, timely detection and treatment in all patients.

Effects of obesity on neuroinflammatory and neurochemical parameters in an animal model of reserpine-induced Parkinson's disease

Obesity is associated with low-grade chronic inflammation and oxidative stress, affecting the brain's reward system by decreasing dopaminergic neurotransmission. It is known that dopaminergic neurotransmission is also reduced in Parkinson's disease (PD), and high adiposity is considered a risk factor for the development of several neurodegenerative diseases, including PD. This study aimed to assess the effects of obesity on neuroinflammatory and neurochemical parameters in an animal model of reserpine-induced PD. The obese group showed increased inflammation and oxidative damage as well as inhibition of mitochondrial respiratory chain complexes I and II and DNA damage in the evaluated structures. The PD group did not show inflammation or mitochondrial dysfunction but exhibited oxidative damage in the hippocampus. The combination group (obesity + PD) showed reduced inflammation and oxidative stress and increased activity of complexes I and II of the mitochondrial respiratory chain in most of the analyzed structures. On the other hand, obesity + PD caused oxidative damage to proteins in the liver, prefrontal cortex, striatum, and cerebral cortex and oxidative stress in the hypothalamus, resulting in reduced catalase activity. Furthermore, the combination group showed DNA damage in blood, liver, and cerebral cortex. In conclusion, it was observed that the association of obesity and PD did not increase inflammation, oxidative stress, or mitochondrial dysfunction in most of the evaluated structures but increased oxidative damage and induced mechanisms that led to DNA damage in peripheral tissues and brain structures.

The Impact of Obesity, Adipose Tissue, and Tumor Microenvironment on Macrophage Polarization and Metastasis

Tumor metastasis is a major cause of death in cancer patients. It involves not only the intrinsic alterations within tumor cells, but also crosstalk between these cells and components of the tumor microenvironment (TME). Tumorigenesis is a complex and dynamic process, involving the following three main stages: initiation, progression, and metastasis. The transition between these stages depends on the changes within the extracellular matrix (ECM), in which tumor and stromal cells reside. This matrix, under the effect of growth factors, cytokines, and adipokines, can be morphologically altered, degraded, or reorganized. Many cancers evolve to form an immunosuppressive TME locally and create a pre-metastatic niche in other tissue sites. TME and pre-metastatic niches include myofibroblasts, immuno-inflammatory cells (macrophages), adipocytes, blood, and lymphatic vascular networks. Several studies have highlighted the adipocyte-macrophage interaction as a key driver of cancer progression and dissemination. The following two main classes of macrophages are distinguished: M1 (pro-inflammatory/anti-tumor) and M2 (anti-inflammatory/pro-tumor). These cells exhibit distinct microenvironment-dependent phenotypes that can promote or inhibit metastasis. On the other hand, obesity in cancer patients has been linked to a poor prognosis. In this regard, tumor-associated adipocytes modulate TME through the secretion of inflammatory mediators, which modulate and recruit tumor-associated macrophages (TAM). Hereby, this review describes the cellular and molecular mechanisms that link inflammation, obesity, and cancer. It provides a comprehensive overview of adipocytes and macrophages in the ECM as they control cancer initiation, progression, and invasion. In addition, it addresses the mechanisms of tumor anchoring and recruitment for M1, M2, and TAM macrophages, specifically highlighting their origin, classification, polarization, and regulatory networks, as well as their roles in the regulation of angiogenesis, invasion, metastasis, and immunosuppression, specifically highlighting the role of adipocytes in this process.

Gastroesophageal Cancer After Gastric Bypass Surgeries: a Systematic Review and Meta-analysis

Data comparing the occurrence of gastroesophageal cancer after gastric bypass procedures are lacking and are only available in the form of case reports. We perform in this study a systematic review and a meta-analysis of all the reported cases of gastroesophageal cancer following Roux-en-Y gastric bypass (RYGB) and loop gastric bypass-one anastomosis gastric bypass/mini gastric bypass (LGB-OAGB/MGB). We conducted a systematic review of all the reported cases in articles referenced in PubMed/Medline, Cochrane, and Scholar Google. Only cases of gastro-esophageal adenocarcinoma following RYGB or LGB-OAGB/MGB are included. Statistical analysis was done accordingly. Fifty cases were identified, along with 2 reported in this paper. Sixty-one percent (27/44) of the cancers after RYGB were in the gastric tube compared to 37.5% (3/8) after LGB-OAGB/MGB. This resulted in an odds ratio of 0.38 (p-value = 0.26), which failed to prove an increase in cancer occurrence in the gastric tube after LGB-MGB/OAGB compared to RYGB. The most common symptoms were dysphagia for cancers occurring in the gastric tube (15/30) and abdominal pain for those occurring in the excluded stomach (10/22). Twenty-nine/thirty of the cancers in the gastric tube were diagnosed by gastroscopy and 13/22 of the cancers in the excluded stomach were diagnosed by CT scan. Gastroesophageal cancers after gastric bypass procedures occur commonly in the excluded stomach where many are not identified by conventional means. Physician awareness and patient education as well as lifelong follow-up are essential for maintaining bypass surgeries on the beneficial side.

Insulin/IGF-1 Signaling Is Downregulated in Barrett's Esophagus Patients Undergoing a Moderate Calorie and Protein Restriction Program: A Randomized 2-Year Trial

Obesity and associated insulin resistance (Ins-R) have been identified as important risk factors for esophageal adenocarcinoma development. Elevated calories and protein consumption are also associated with Ins-R and glucose intolerance. We investigated the effect of a 24-month moderate calorie and protein restriction program on overweight or obese patients affected by Barrett’s esophagus (BE), as no similar dietary approach has been attempted to date in this disease context. Anthropometric parameters, levels of serum analytes related to obesity and Ins-R, and the esophageal insulin/IGF-1 signaling pathway were analyzed. This study is registered with ClinicalTrials.gov, number NCT03813381. Insulin, C-peptide, IGF-1, IGF-binding protein 3 (IGFBP3), adipokines, and esophageal expression of the main proteins involved in insulin/IGF-1 signal transduction were quantified using Luminex-XMAP^® technology in 46 patients who followed the restriction program (IA) and in 54 controls (CA). Body mass index and waist circumference significantly decreased in 76.1% of IA and 35.2% of CA. IGF-1 levels were reduced in 71.7% of IA and 51.8% of CA. The simultaneous reduction of glycaemia, IGF-1, the IGF-1/IGFBP3 ratio, and the improvement in weight loss-dependent insulin sensitivity, were associated with the downregulation of the insulin/IGF-1 signal on BE tissue. The proposed intervention program was an effective approach to counteract obesity-associated cancer risk factors. The improvement in metabolic condition resulted in a downregulation of the ERK-mediated mitogenic signal in 43.5% of patients, probably affecting the molecular mechanism driving adenocarcinoma development in BE lesions.

Mitochondrial DNA Copy Number Variations in Gastrointestinal Tract Cancers: Potential Players

Alterations of mitochondria have been linked to several cancers. Also, the mitochondrial DNA copy number (mtDNA-CN) is altered in various cancers, including gastrointestinal tract (GIT) cancers, and several research groups have investigated its potential as a cancer biomarker. However, the exact causes of mtDNA-CN variations are not yet revealed. This review discussed the conceivable players in this scheme, including reactive oxygen species (ROS), mtDNA genetic variations, DNA methylation, telomere length, autophagy, immune system activation, aging, and infections, and discussed their possible impact in the initiation and progression of cancer. By further exploring such mechanisms, mtDNA-CN variations may be effectively utilized as cancer biomarkers and provide grounds for developing novel cancer therapeutic agents.

Tissue distribution of γδ T cell subsets in oesophageal adenocarcinoma

The global obesity epidemic is contributing to increased prevalence of diseases fuelled by chronic inflammation, including cancer. Oesophageal adenocarcinoma (OAC) is an obesity-associated malignancy with increasing prevalence, dismal prognosis, and severely dysregulated immune processes. We previously reported that αβ T cells migrate to omentum and liver in OAC and contribute to inflammation in these tissues. Here, we assessed the tissue distribution and phenotype of gamma/delta (γδ) T cells in the blood, omentum, liver and tumour of OAC patients. Our data show that the Vδ1 and Vδ3 subsets of γδ T cells are most prevalent in omentum and liver of OAC patients. Furthermore, γδ T cells are predominantly pro-inflammatory in these tissues, and co-express IFN-γ and IL-17. Moreover, γδ T cells exhibit cytotoxic capabilities in OAC omentum and liver. This study provides the first indication that γδ T cells contribute to obesity-associated inflammation in OAC and might be exploited therapeutically.

Prognostic implications of visceral obesity on gastric adenocarcinoma: does it really matter?

PURPOSE

To evaluate the association of visceral adiposity measured on computed tomography (CT) in preoperative period with lymph node (LN) metastasis and overall survival in gastric adenocarcinoma patients.

METHODS

Preoperative CT scans of 246 gastric adenocarcinoma patients who did not receive neoadjuvant chemoradiotherapy were evaluated. Visceral fat area (VFA), subcutaneous fat area (SFA) and Total fat area (TFA), VFA/TFA ratio were quantified by CT. VFA/TFA > 29% was defined as visceral obesity. The differentiation, t-stage, n-stage and the number of harvested-metastatic LNs were noted. The maximum thickness of tumor and localization were recorded from CT. Chi-square, Student's t-test, multiple Cox regression, Spearman's correlation coefficient, and Kaplan-Meier algorithm were performed.

RESULTS

The overall survival (OS) rates and N-stage were not different significantly between viscerally obese and non-obese group (p = 0.994, p = 0.325). The number of metastatic LNs were weakly inversely correlated with VFA (r = -0.144, p = 0.024). Univariate analysis revealed no significant association between visceral obesity and OS or LN metastasis (p = 0.377, p = 0.736). In multivariate analyses, OS was significantly associated with poorly differentiation (HR = 1.72, 95% CI =1.04-2.84, p = 0.035), higher pathologic T and N stage (T4 vs T1 + T2 HR = 2.67, 95% CI =1.18-6.04, p = 0.019; T3 vs T1 + T2 HR = 1.98, 95% CI = 0.90-4.33, p = 0.089; N3b vs N0 HR = 2.97, 95% CI1.45-6.0, p = 0.003; N3 (3a+ 3b) vs N0 HR = 2.24 95% CI =1.15-4.36, p = 0.018).

CONCLUSION

Visceral obesity may not be a prognostic factor in resectable gastric adenocarcinoma patients.

Peptides-based therapy and diagnosis. Strategies for non-invasive therapies in cancer

In recent years, remarkable progress was registered in the field of cancer research. Though, cancer still represents a major cause of death and cancer metastasis a problem seeking for urgent solutions as it is the main reason for therapeutic failure. Unfortunately, the most common chemotherapeutic agents are non-selective and can damage healthy tissues and cause side effects that affect dramatically the quality of life of the patients. Targeted therapy with molecules that act specifically at the tumour sites interacting with overexpressed cancer receptors is a very promising strategy for achieving the specific delivery of anticancer drugs, radioisotopes or imaging agents. This review aims to give an overview on different strategies for targeting cancer cell receptors localised either at the extracellular matrix or at the cell membrane. Molecules like antibodies, aptamers and peptides targeting the cell surface are presented with advantages and disadvantages, with emphasis on peptides. The most representative peptides are described, including cell penetrating peptides, homing and anticancer peptides with particular consideration on recent discoveries.

Dynamic Changes of Mitochondrial DNA Copy Number in Gastrointestinal Tract Cancers: A Systematic Review and Meta-Analysis

We have performed a systematic review and meta-analysis for evaluation of mitochondrial DNA copy number (mtDNA-CN) alterations in peripheral blood leukocytes (PBL), and tumor tissues of gastrointestinal tract (GIT) cancers. Analysis of the PBL demonstrated a significant decrease [OR: 0.6 (0.5, 0.8)] and increase [OR: 1.4 (1.1, 1.9)] prior to and following GIT cancer development, respectively. This trend was more evident in CRC, and GC subgroups. Analysis of tissue yielded high levels of heterogeneity. However, the mean difference for the CRC subgroup was statistically significant [1.5 (1.0, 2.2)]. Our analysis suggests mtDNA-CN deserves further investigations as a GIT-cancer screening tool.

Updated Review on the Role of Curcumin in Gastrointestinal Cancers

Malignant conditions of the gastrointestinal tract and accessory organs of digestion, including the oral cavity, esophagus, stomach, biliary system, pancreas, small intestine, large intestine, rectum and anus, are referred to as gastrointestinal cancers. Curcumin is a natural compound derived from turmeric with a wide range of biological activities. Several in vitro and in vivo studies have investigated the effects of curcumin on gastrointestinal cancers. In the current review, we aimed to provide an updated summary on the recent findings regarding the beneficial effects of curcumin on different gastrointestinal cancers in the recent decade. For this purpose, ScienceDirect," "Google Scholar," "PubMed," "ISI Web of Knowledge," and "Wiley Online Library" databases were searched using "curcumin", "cancer", and "gastrointestinal organs" as keywords. In vitro studies performed on different gastrointestinal cancerous cell lines have shown that curcumin can inhibit cell growth through cycle arrest at the G2/M and G1 phases, as well as stimulated apoptosis and autophagy by interacting with multiple molecular targets. In vivo studies performed in various animal models have confirmed mainly the chemopreventive effects of curcumin. Several nano-formulations have been proposed to improve the bioavailability of curcumin and increase its absorption. Moreover, curcumin has been used in combinations with many anti-tumor drugs to increase their anticarcinogenic properties. Taken together, curcumin falls within the category of plant-derived substances capable of preventing or treating gastrointestinal cancers. Further studies, particularly clinical trials, on the efficacy and safety of curcumin are suggested in this regard.

Anthropometry, body fat composition and reproductive factors and risk of oesophageal and gastric cancer by subtype and subsite in the UK Biobank cohort

BACKGROUND

Obesity has been positively associated with upper gastrointestinal cancers, but prospective data by subtype/subsite are limited. Obesity influences hormonal factors, which may play a role in these cancers. We examined anthropometry, body fat and reproductive factors in relation to oesophageal and gastric cancer by subtype/subsite in the UK Biobank cohort.

METHODS

Among 458,713 UK Biobank participants, 339 oesophageal adenocarcinomas, 124 oesophageal squamous cell carcinomas, 137 gastric cardia and 92 gastric non-cardia cancers were diagnosed during a mean of 6.5 years follow-up. Cox models estimated multivariable hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Body mass index (BMI), hip circumference, waist circumference, waist-to-hip ratio, waist-to-height ratio, total body fat and trunk fat were positively associated with oesophageal adenocarcinoma (highest vs lowest category: HR = 2.33, 95%-CI:1.65-3.28; HR = 1.56, 95%-CI:1.15-2.13; HR = 2.30, 95%-CI:1.47-3.57; HR = 1.71, 95%-CI:1.01-2.90; HR = 2.87, 95%-CI:1.88-4.38; HR = 1.96, 95%-CI:1.30-2.96; HR = 2.34, 95%-CI:1.70-3.22, respectively). Although there were no statistically significant associations in combined sex analyses, BMI (HR = 1.83, 95%-CI:1.00-3.37), waist circumference (HR = 2.21, 95%-CI:1.27-3.84) and waist-to-hip ratio (HR = 1.92, 95%-CI:1.11-3.29) were associated with gastric cardia cancer in men; however, mutual adjustment attenuated the associations for BMI and waist-to-hip ratio. For oesophageal squamous cell carcinoma, statistically significant inverse associations were observed among women for BMI, hip circumference, waist circumference, waist-to-height ratio, total body fat and trunk fat, although they were based on small numbers. In addition, older age at first (HR = 0.44, 95%-CI:0.22-0.88) and last live birth (HR = 0.44, 95%-CI:0.22-0.87) were inversely associated with oesophageal squamous cell carcinoma and having a stillbirth/miscarriage/termination was positively associated (HR = 1.84, 95%-CI:1.10-3.07).

CONCLUSIONS

Obesity and abdominal obesity specifically may be a risk factor for oesophageal adenocarcinoma and gastric cardia cancer in men. Some reproductive factors may be associated with oesophageal squamous cell carcinoma in women.

Lipoproteins and the Tumor Microenvironment

The tumor microenvironment (TME) plays a key role in enhancing the growth of malignant tumors and thus contributing to "aggressive phenotypes," supporting sustained tumor growth and metastasis. The precise interplay between the numerous components of the TME that contribute to the emergence of these aggressive phenotypes is yet to be elucidated and currently under intense investigation. The purpose of this article is to identify specific role(s) for lipoproteins as part of these processes that facilitate (or oppose) malignant growth as they interact with specific components of the TME during tumor development and treatment. Because of the scarcity of literature reports regarding the interaction of lipoproteins with the components of the tumor microenvironment, we were compelled to explore topics that were only tangentially related to this topic, to ensure that we have not missed any important concepts.

A System Biology-Based Approach for Designing Combination Therapy in Cancer Precision Medicine

In this paper, we have used an agent-based stochastic tumor growth model and presented a mathematical and theoretical perspective to cancer therapy. This perspective can be used to theoretical study of precision medicine and combination therapy in individuals. We have conducted a series of in silico combination therapy experiments. Based on cancer drugs and new findings of cancer biology, we hypothesize relationships between model parameters which in some cases represent individual genome characteristics and cancer drugs, i.e., in our approach, therapy players are delegated by biologically reasonable parameters. In silico experiments showed that combined therapies are more effective when players affect tumor via different mechanisms and have different physical dimensions. This research presents for the first time an algorithm as a theoretical viewpoint for the prediction of effectiveness and classification of therapy sets.

Anti-Adipogenic Effect of Neferine in 3T3-L1 Cells and Primary White Adipocytes

Neferine, an alkaloid component extracted from lotus seed embryos, is known for its anti-inflammatory, anticancer, and antioxidant properties. However, the anti-adipogenic activity of neferine has not been thoroughly investigated. In this study, neferine was found to inhibit lipid accumulation in a dose-dependent manner during the differentiation of 3T3-L1 cells without inducing cytotoxicity. Real-time polymerase chain reaction and immunoblot analysis revealed the downregulation in the expression of peroxisome proliferator activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), sterol regulatory element-binding protein-1c (SREBP-1c), and fatty acid synthase (FAS) and the upregulation in carnitine palmitoyltransferase-1 (CPT-1) and sirtuin 1 (SIRT1) levels following neferine treatment. Furthermore, neferine increased the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), which is an important regulator of fatty acid oxidation. Our result indicates that neferine attenuates adipogenesis and promotes lipid metabolism by activating AMPK-mediated signaling. Therefore, neferine may serve as a therapeutic candidate for obesity treatment.

Efficacy and safety of Gelidium elegans intake on bowel symptoms in obese adults: A 12-week randomized double-blind placebo-controlled trial

BACKGROUND/AIMS

Gelidium elegans (GE) is known to have antiobesity effects and beneficial effects on functional bowel symptoms in preclinical studies. The aim of this study was to determine the efficacy and safety of GE intake on bowel symptoms in obese human adults.

METHODS

This 12-week single-center randomized double-blind placebo-controlled study was performed from September 2016 to May 2017. Consecutive obese subjects were randomly assigned (1:1) to either GE (1 g) or placebo (1 g) once daily group for 12 weeks. Patients' bowel symptoms were evaluated using the Bristol Stool Form Scale, Constipation Scoring System (CSS), and Patient Assessment of Constipation-Symptoms (PAC-SYM) questionnaire.

RESULTS

The stool symptom score of PAC-SYM significantly improved in the GE group compared with the placebo group after the 12-week treatment (P = .041). Abdominal discomfort score of CSS significantly decreased at 12 weeks compared to that at baseline in the GE group (P = .003), but not in the placebo group (P = .398). In addition, abdominal discomfort score of CSS slightly decreased in the GE group compared with the placebo group after the 12-week treatment (P = .060). However, stool consistency, total CSS score, and PAC-SYM score did not change significantly in both GE group and the placebo group over the 12-week treatment period.

CONCLUSIONS

GE treatment for 12 weeks improved the stool symptom score on the PAC-SYM and abdominal discomfort score on the CSS in obese adults. However, further research is needed in large-scale human studies.

Obesity, Inflammation, and Cancer

Obesity, a worldwide epidemic, confers increased risk for multiple serious conditions, including cancer, and is increasingly recognized as a growing cause of preventable cancer risk. Chronic inflammation, a well-known mediator of cancer, is a central characteristic of obesity, leading to many of its complications, and obesity-induced inflammation confers additional cancer risk beyond obesity itself. Multiple mechanisms facilitate this strong association between cancer and obesity. Adipose tissue is an important endocrine organ, secreting several hormones, including leptin and adiponectin, and chemokines that can regulate tumor behavior, inflammation, and the tumor microenvironment. Excessive adipose expansion during obesity causes adipose dysfunction and inflammation to increase systemic levels of proinflammatory factors. Cells from adipose tissue, such as cancer-associated adipocytes and adipose-derived stem cells, enter the cancer microenvironment to enhance protumoral effects. Dysregulated metabolism that stems from obesity, including insulin resistance, hyperglycemia, and dyslipidemia, can further impact tumor growth and development. This review describes how adipose tissue becomes inflamed in obesity, summarizes ways these mechanisms impact cancer development, and discusses their role in four adipose-associated cancers that demonstrate elevated incidence or mortality in obesity.

No Decreased Risk of Gastrointestinal Cancers in Users of Metformin in The Netherlands; A Time-Varying Analysis of Metformin Exposure

Previous studies on metformin use and gastrointestinal (GI) cancer risk have yielded inconclusive results on metformin's chemoprotective effects. We aimed to evaluate GI cancer risk in users of metformin in The Netherlands using a time-varying approach in a large population-based database. A cohort study was performed using the NCR-PHARMO database. Patients using ≥1 non-insulin antidiabetic drug (NIAD) during 1998 to 2011 were included (N = 57,621). Exposure to NIADs was modeled time-varyingly. Cox regression analysis estimated HRs of GI cancers in current metformin users versus current users of other NIADs. Covariables included age, sex, drugs known to impact cancer risk, history of hospitalization, and starting year of follow-up. A sensitivity analysis was performed, applying a new-user design. Current use of metformin was not associated with a decreased risk of GI cancer [HR, 0.97; 95% confidence interval (CI), 0.82-1.15] or specific GI cancer sites. The sensitivity analysis yielded comparable results. No decreasing trends were observed with increasing cumulative dose of metformin [HR 1.05, 95% CI, 0.85-1.28; HR 0.89, 95% CI, 0.73-1.10; HR 0.96, 95% CI, 0.77-1.19 for dose tertiles low (<405 g), medium (405-999 g), and high (≥999 g)]. In contrast, an increased risk of pancreatic cancer was found in current users of metformin plus insulin (HR, 4.90; 95% CI, 2.64-9.10). In conclusion, no decreased risk of GI cancer was found in current metformin users compared with current users of other NIADs. Variations in the exposure definition of metformin use may be one of the explanations of previously found reduced cancer risks in metformin users. Cancer Prev Res; 10(5); 290-7. ©2017 AACR.

Role of tumor microenvironment in tumorigenesis

Tumorigenesis is a complex and dynamic process, consisting of three stages: initiation, progression, and metastasis. Tumors are encircled by extracellular matrix (ECM) and stromal cells, and the physiological state of the tumor microenvironment (TME) is closely connected to every step of tumorigenesis. Evidence suggests that the vital components of the TME are fibroblasts and myofibroblasts, neuroendocrine cells, adipose cells, immune and inflammatory cells, the blood and lymphatic vascular networks, and ECM. This manuscript, based on the current studies of the TME, offers a more comprehensive overview of the primary functions of each component of the TME in cancer initiation, progression, and invasion. The manuscript also includes primary therapeutic targeting markers for each player, which may be helpful in treating tumors.

Potential Benefit of Metformin as Treatment for Colon Cancer: the Evidence so Far

Metformin is known as a hypoglycaemic agent that regulates glucose homeostasis by inhibiting liver glucose production and increasing muscle glucose uptake. Colorectal cancer (CRC) is one of the most common cancers worldwide, with about a million new cases diagnosed each year. The risk factors for CRC include advanced age, smoking, black race, obesity, low fibre diet, insulin resistance, and the metabolic syndrome. We have searched Medline for the metabolic syndrome and its relation to CRC, and metformin as a potential treatment of colorectal cancer. Administration of metformin alone or in combination with chemotherapy has been shown to suppress CRC. The mechanism that explains how insulin resistance is associated with CRC is complex and not fully understood. In this review we have summarised studies which showed an association with the metabolic syndrome as well as studies which tackled metformin as a potential treatment of CRC. In addition, we have also provided a summary of how metformin at the cellular level can induce changes that suppress the activity of cancer cells.

Non-Alcoholic Fatty Liver Disease and Extra-Hepatic Cancers

Non-alcoholic fatty liver disease (NAFLD) is a leading cause of chronic liver disease but the second cause of death among NAFLD patients are attributed to malignancies at both gastrointestinal (liver, colon, esophagus, stomach, and pancreas) and extra-intestinal sites (kidney in men, and breast in women). Obesity and related metabolic abnormalities are associated with increased incidence or mortality for a number of cancers. NAFLD has an intertwined relationship with metabolic syndrome and significantly contributes to the risk of hepatocellular carcinoma (HCC), but recent evidence have fuelled concerns that NAFLD may be a new, and added, risk factor for extra-hepatic cancers, particularly in the gastrointestinal tract. In this review we critically appraise key studies on NAFLD-associated extra-hepatic cancers and speculate on how NAFLD may influence carcinogenesis at these sites.

An Analysis of Weight Gains and Body Mass Index in Patients with Barrett's Esophagus

BACKGROUND

Obesity is a risk factor for developing Barrett's esophagus (BE), a precursor to esophageal cancer. Long BE lengths are associated with greater risk for malignancy. How weight gains from young adulthood (defined as ages 19 to 29 years) affect BE length is unknown.

OBJECTIVE

To examine current body mass index (BMI), weight gains from young adulthood, and evening snacking near bedtime during young adulthood in BE patients.

DESIGN

Cross-sectional analysis of 71 patients from 2001 to 2008 from a 600-bed tertiary care center in the United States who were newly diagnosed with BE by endoscopy and mucosal biopsies.

MAIN OUTCOME MEASURES

Barrett's esophagus length and age at presentation.

STATISTICAL ANALYSES PERFORMED

Pearson's correlation coefficient (r) measured the linear association between continuous variables. The Kruskal-Wallis test was used to compare medians by segment length and the chi-squared test or Fisher's exact test for categorical data. Quantile regression was used for multivariable adjustment.

RESULTS

Younger patients had higher BMIs at diagnosis (r=-0.32, P=0.007). Patients who gained more than 23 kg from young adulthood were diagnosed at an adjusted median age of 18.0 years younger 95% CI (6.1-29.9, P=0.004) than patients with no weight gains. BMI was not correlated with BE length (r=-0.12, P=0.33). Weight gains from young adulthood were not associated with BE length after multivariable adjustment (P=0.19). Patients whose late evening snack or bedtime was less than 4 hours from dinner had longer median BE lengths than those who went to bed later (5 vs 2 cm, P=0.02).

CONCLUSIONS

Longer BE lengths were associated with shorter dinner-bedtime intervals during young adulthood but not with current BMI or weight gains from young adulthood.

Obesity-associated cancer: an immunological perspective

Epidemiological studies have established an association between obesity, insulin resistance, type 2 diabetes and a number of cancer types. Research has focused predominantly on altered endocrine factors, growth factors and signalling pathways, with little known in man about the immune involvement in the relevant pathophysiological processes. Moreover, in an era of exciting new breakthroughs in cancer immunotherapy, there is also a need to study the safety and efficacy of immunotherapeutics in the complex setting of inflammatory-driven obesity-associated cancer. This review addresses key immune cell subsets underpinning obesity-associated inflammation and describes how such immune compartments might be targeted to prevent and treat obesity-associated cancer. We propose that the modulation, metabolism, migration and abundance of pro- and anti-inflammatory cells and tumour-specific T cells might be therapeutically altered to both restore immune balance, alleviating pathological inflammation, and to improve anti-tumour immune responses in obesity-associated cancer.

The mTOR pathway in obesity driven gastrointestinal cancers: Potential targets and clinical trials

The mechanistic target of rapamycin (mTOR) is a crucial point of convergence between growth factor signalling, metabolism, nutrient status and cellular proliferation. The mTOR pathway is heavily implicated in the progression of many cancers and is emerging as an important driver of gastrointestinal (GI) malignancies. Due to its central role in adapting metabolism to environmental conditions, mTOR signalling is also believed to be critical in the development of obesity. Recent research has delineated that excessive nutrient intake can promote signalling through the mTOR pathway and possibly evoke changes to cellular metabolism that could accelerate obesity related cancers. Acting through its two effector complexes mTORC1 and mTORC2, mTOR dictates the transcription of genes important in glycolysis, lipogenesis, protein translation and synthesis and has recently been defined as a central mediator of the Warburg effect in cancer cells. Activation of the mTOR pathway is involved in both the pathogenesis of GI malignancies and development of resistance to conventional chemotherapy and radiotherapy. The use of mTOR inhibitors is a promising therapeutic option in many GI malignancies, with greatest clinical efficacy seen in combination regimens. Recent research has also provided insight into crosstalk between mTOR and other pathways which could potentially expand the list of therapeutic targets in the mTOR pathway. Here we review the available strategies for targeting the mTOR pathway in GI cancers. We discuss current clinical trials of both established and novel mTOR inhibitors, with particular focus on combinations of these drugs with conventional chemotherapy, radiotherapy and targeted therapies.

Analysis of the Human Proteome in Subcutaneous and Visceral Fat Depots in Diabetic and Non-diabetic Patients with Morbid Obesity

No longer regarded as simply a storage depot, fat is a dynamic organ acting locally and systemically to modulate energy homeostasis, glucose sensitivity, insulin resistance, and inflammatory pathways. Here, mass spectrometry was used to survey the proteome of patient matched subcutaneous fat and visceral fat in 20 diabetic vs 22 nondiabetic patients with morbid obesity. A similar number of proteins (~600) were identified in each tissue type. When stratified by diabetic status, 19 and 41 proteins were found to be differentially abundant in subcutaneous fat and omentum, respectively. These proteins represent pathways known to be involved in metabolism. Five of these proteins were differentially abundant in both fat depots: moesin, 78 kDa glucose-regulated protein, protein cordon-bleu, zinc finger protein 611, and cytochrome c oxidase subunit 6B1. Three proteins, decorin, cytochrome c oxidase subunit 6B1, and 78 kDa glucose-regulated protein, were further tested for validation by western blot analysis. Investigation of the proteins reported here is expected to expand on the current knowledge of adipose tissue driven biochemistry in diabetes and obesity, with the ultimate goal of identifying clinical targets for the development of novel therapeutic interventions in the treatment of type 2 diabetes mellitus. To our knowledge, this study is the first to survey the global proteome derived from each subcutaneous and visceral adipose tissue obtained from the same patient in the clinical setting of morbid obesity, with and without diabetes. It is also the largest study of diabetic vs nondiabetic patients with 42 patients surveyed.

Adipose-derived stems cells and their role in human cancer development, growth, progression, and metastasis: a systematic review

Obesity is a well recognized risk factor for several types of cancers, many of which occur solely or disproportionately in women. Adipose tissue is a rich source of adipose-derived stem cells (ASC), which have received attention for their role in cancer behavior. The purpose of this systematic review is to present the existing literature on the role of ASCs in the growth, development, progression, and metastasis of cancer, with an emphasis on malignancies that primarily affect women. To accomplish this goal, the bibliographic database PubMed was systematically searched for articles published between 2001 and 2014 that address ASCs' relationship to human cancer. Thirty-seven articles on ASCs' role in human cancer were reviewed. Literature suggests that ASCs exhibit cancer-promoting properties, influence/are influenced by the tumor microenvironment, promote angiogenesis, and may be associated with pathogenic processes through a variety of mechanisms, such as playing a role in hypoxic tumor microenvironment. ASCs appear to be important contributors to tumor behavior, but research in areas specific to women's cancers, specifically endometrial cancer, is scarce. Also, because obesity continues to be a major health concern, it is important to continue research in this area to improve understanding of the impact adiposity has on cancer incidence.

Visceral abdominal obesity is associated with an increased risk of irritable bowel syndrome

OBJECTIVES

There are several studies considering obesity as the risk factor for various lower gastrointestinal symptoms. But the relationship between visceral abdominal obesity and the incidence of irritable bowel syndrome (IBS) is not studied yet. The aim of this study was to investigate the association between visceral adipose tissue (VAT) and the risk of IBS.

METHODS

This is a case-control study comparing the VAT area between subjects with IBS (IBS group) and controls without IBS (non IBS group), who underwent abdomen computerized tomography (CT) for routine health checkup from January 2012 to August 2013 in a health promotion center. A telephone survey was retrospectively conducted to diagnose IBS by Rome III criteria. The association between IBS and abdominal obesity was evaluated by measuring VAT, subcutaneous adipose tissue (SAT), VAT/SAT ratio, body mass index (BMI) and waist circumference (WC).

RESULTS

The prevalence of IBS was 19.9% (67/336) among all enrolled subjects. In the univariate analysis, VAT area, VAT/SAT ratio, waist circumference, the presence of reflux esophagitis and the ratio of females were significantly higher in the IBS group than in the non IBS group. However, a higher BMI or a higher SAT area is not associated with an increased risk of IBS. In the multivariate analysis, a higher VAT area (odds ratio (OR)=9.42, 95% confidence interval (CI): 2.90-30.64, highest tertile vs. lowest tertile, P=0.001), VAT/SAT ratio (OR=10.15, 95% CI: 3.05-33.58, highest tertile vs. lowest tertile, P=0.001) and waist circumference (OR=7.81, 95% CI: 2.13-28.66, highest tertile vs. lowest tertile, P=0.002) were independently associated with a risk of IBS. Only in the IBS-D group, not in the IBS-C, visceral adiposity was associated with an increased risk of IBS.

CONCLUSIONS

Visceral adiposity measured by VAT, VAT/SAT, and waist circumference is associated with an increased risk of IBS, especially of IBS-D. However, neither SAT nor BMI are associated with an increased risk of IBS.

Pathophysiological mechanisms linking obesity and esophageal adenocarcinoma

In recent decades there has been a dramatic rise in the incidence of esophageal adenocarcinoma (EAC) in the developed world. Over approximately the same period there has also been an increase in the prevalence of obesity. Obesity, especially visceral obesity, is an important independent risk factor for the development of gastro-esophageal reflux disease, Barrett’s esophagus and EAC. Although the simplest explanation is that this mediated by the mechanical effects of abdominal obesity promoting gastro-esophageal reflux, the epidemiological data suggest that the EAC-promoting effects are independent of reflux. Several, not mutually exclusive, mechanisms have been implicated, which may have different effects at various points along the reflux-Barrett’s-cancer pathway. These mechanisms include a reduction in the prevalence of Helicobacter pylori infection enhancing gastric acidity and possibly appetite by increasing gastric ghrelin secretion, induction of both low-grade systemic inflammation by factors secreted by adipose tissue and the metabolic syndrome with insulin-resistance. Obesity is associated with enhanced secretion of leptin and decreased secretion of adiponectin from adipose tissue and both increased leptin and decreased adiponectin have been shown to be independent risk factors for progression to EAC. Leptin and adiponectin have a set of mutually antagonistic actions on Barrett’s cells which appear to influence the progression of malignant behaviour. At present no drugs are of proven benefit to prevent obesity associated EAC. Roux-en-Y reconstruction is the preferred bariatric surgical option for weight loss in patients with reflux. Statins and aspirin may have chemopreventative effects and are indicated for their circulatory benefits.

The role of obesity in oesophageal cancer development

The incidence of oesophageal adenocarcinoma has increased dramatically in the developed world in the last half century. Over approximately the same period there has been an increase in the prevalence of obesity. Multiple epidemiological studies and meta-analyses have confirmed that obesity, especially abdominal, visceral obesity, is a risk factor for gastro-oesophageal reflux, Barrett's oesophagus and oesophageal adenocarcinoma. Although visceral obesity enhances gastro-oesophageal reflux, the available data also show that visceral obesity increases the risk of Barrett's oesophagus and adenocarcinoma via reflux-independent mechanisms. Several possible mechanisms could link obesity with the risk of oesophageal adenocarcinoma in addition to mechanical effects increasing reflux. These include reduced gastric Helicobacter pylori infection, altered intestinal microbiome, factors related to lifestyle, the metabolic syndrome and associated low-grade inflammation induced by obesity and the secretion of mediators by adipocytes which may directly influence the oesophageal epithelium. Of these adipocyte-derived mediators, increased leptin levels have been independently associated with progression to oesophageal adenocarcinoma and in laboratory studies leptin enhances malignant behaviours in cell lines. Adiponectin is also secreted by adipocytes and levels decline with obesity: decreased serum adiponectin levels are associated with malignant progression in Barrett's oesophagus and experimentally adiponectin exerts anticancer effects in Barrett's cell lines and inhibits growth factor signalling. At present there are no proven chemopreventative interventions that may reduce the incidence of obesity-associated oesophageal cancer: observational studies suggest that the combined use of a statin and aspirin or another cyclo-oxygenase inhibitor is associated with a significantly reduced cancer incidence in patients with Barrett's oesophagus.