Excess adiposity and gastrointestinal cancer

Impact of obesity on survival outcomes of women with advanced epithelial ovarian cancer in Lagos, Nigeria: a retrospective cohort study

Background

Epithelial ovarian cancer (EOC) is a major contributor to cancer-related illness and death among women worldwide. Obesity, a prevalent condition in many populations, has been implicated as a risk factor for various malignancies including EOC.

Objectives

This study investigated the impact of obesity on survival outcomes among women with advanced EOC in Lagos, Nigeria.

Methods

We conducted a retrospective analysis of patient medical records from a major gynaecological cancer unit of a teaching hospital in Lagos, Southwest Nigeria, to examine the relationship between body mass index (BMI) 30 kg/m2 as a measure of obesity, and progression-free (PFS) and overall survival (OS). We used Kaplan-Meier analysis stratified by patients' BMI categories (obese versus non-obese) and compared using the Log Rank test to estimate PFS and OS. The multivariable Cox proportional hazard model was used to estimate hazard ratios (HR) of the associations between the BMI categories and survival outcomes while adjusting for all confounding clinicopathologic variables. Hypothesis tests were conducted using a two-tailed approach with a significance level of 5%.

Results

Our study showed no statistically significant association between obesity and PFS (adjusted HR = 0.62, 95% confidence interval = 0.36-1.06, p = 0.282). However, a significant association was observed between obesity with or without ascites and OS (adjusted HR = 3.58, 95% confidence interval 1.28-10.02, p = 0.015).

Conclusion

Our findings suggest that obesity negatively impacts OS in patients with EOC, thus highlighting the need to address obesity in the management of EOC by introducing comprehensive, multidisciplinary approaches incorporating weight management and personalized treatment strategies to enhance the prognosis of these patients.

An Assessment of Behavioral Risk Factors in Oncology Patients

An evaluation of the behavioral risk factors that contribute to the incidence and evolution of cancer in oncology patients was conducted through a cross-sectional study using a questionnaire completed by 206 patients (101 men and 105 women) diagnosed with various types of cancer. These patients were selected from different oncology centers in Romania, located in Bucharest and Constanta. Among the respondents, 91 are of normal weight, 12 are underweight, 62 are overweight, and 41 are obese, with overweight individuals predominating (p = 0.799). Regarding the presence of behavioral risk factors that can aggravate oncological pathology, it is found that 10 respondents consume alcohol daily, 36 consume it weekly with varying frequencies (p = 0.012), 26 respondents smoke excessively daily, and 12 respondents smoke 1-2 cigarettes daily (p = 0.438). Additionally, 40 respondents rarely engage in physical activity, and 71 respondents do not engage in physical activity at all as they do not typically participate in sports (p = 0.041). Thus, respondents with colon cancer tend to consume sweets, pastries and even fast food or fried foods more often, while the daily consumption of vegetables and fruits is insufficient, according to the recommendations of nutrition guidelines (a minimum of four portions per day). The analysis found that smoking and excessive alcohol consumption were associated with an increased incidence of lung and liver cancer. The lack of regular physical activity was identified as a risk factor for breast and colon cancer. An unhealthy diet, characterized by a low consumption of fruits and vegetables and high intake of processed foods, was correlated with a higher incidence of colorectal cancer. Additionally, non-adherence to medical advice was associated with poorer clinical outcomes and faster disease progression. The majority of respondents who declared that they did not feel an improvement in their state of health in the last period were among those who stated that they did not fully comply with the oncologist's recommendations. Identifying and modifying behavioral risk factors can play a crucial role in cancer prevention and in improving the prognosis and quality of life of cancer patients.

Incidence of cancer for patients after bariatric surgery: evidence from 33 cohort studies

BACKGROUND

With the rising prevalence of severe obesity, bariatric surgery has emerged as a crucial treatment option. As the number of surgeries performed worldwide increases, there has been growing interest in the impact of bariatric surgery on cancer incidence. While several studies have examined this relationship, the topic remains controversial.

OBJECTIVES

We conducted this systematic review of cohort studies with meta-analysis to evaluate the effect of bariatric surgery versus nonsurgical treatment on overall cancer incidence. However, the effects may vary when focusing on specific cancer types, surgical procedures, or gender, so we conducted additional subgroup analyses.

SETTING

A meta-analysis. University hospital.

METHODS

The Cochrane, Embase, PubMed, and Web of Science databases were searched for studies from 1 January 2000 to 1 December 2022. Meta-analysis was conducted to evaluate the pooled effect and further implemented subgroup analysis stratified by cancer type, operation type, and sex.

RESULTS

All cohort studies were included in this meta-analysis from 18,216 studies. The overall cancer incidence demonstrated a significant decrease in the group with bariatric surgery (odds ratios [OR] = .56, P = .000, 95% CI .46 to .68). In subgroup analysis, similar decrease effect was found in 9 cancers. Furthermore, the incidence of cancer decreased significantly in male (OR = .66, P = .001, 95% CI .51 to .85) and female patients (OR = .63, P = .000, 95% CI .57 to .69) and patients undergoing gastric bypass (OR = .46, P = .000, 95% CI .33 to .63) or sleeve gastrectomy (OR = .44, P = .001, 95% CI .27 to .70).

CONCLUSIONS

In the overall analysis, bariatric surgery could reduce the incidence of cancer significantly. Further large-scale well-matched studies are needed to verify the protective effect of bariatric surgery on cancer incidence.

An Overview of Recent Findings that Shed Light on the Connection between Fat and Cancer

Obesity and cancer have been found to have a direct link in epidemiological studies. Obesity raises the risk of cancer and associated chronic disorders. Furthermore, an imbalance of adipokines, like leptins, plays a crucial role in neoplasm pathogenesis, cell migration, and thereby, cancer metastasis. Also, leptin increases human epidermal growth factor receptor 2 (HER2) protein levels through the STAT3-mediated (signal transducer and activator of transcription) upregulation of heat shock protein (Hsp90) in breast cancer cells. It has been noticed that insulin and insulin-like growth factors (IGFs) act as mitosis activators in the host and cancerous breast epithelial cells. The condition of hyperinsulinemia explains the positive association between colorectal cancer and obesity. Furthermore, in prostate cancer, an alteration in sex hormone levels, testosterone and dihydrotestosterone, has been reported to occur, along with increased oxidative stress, which is the actual cause of the tumors. Whereas, there have been two interconnected factors that play a crucial role in the psychological cycle concerned with lung cancer. The review article focuses on all the prospects of etiological mechanisms that have found linkage with obesity and breast, colon, lung, and prostate cancers. Furthermore, the article has also highlighted how these new insights into the processes occur and, due to which reasons, obesity contributes to tumorigenesis. This review provides a detailed discussion on the progression, which can assist in the development of new and innovative techniques to interfere in this process, and it has been supported with insights based on evidence literature on approved clinical treatments for obesity and cancer.

Gallbladder Cancer

Gallbladder carcinoma (GBC) is the most common biliary epithelial malignancy, with an estimated incidence of 1.13 cases per 100,000 in the United States (Hundal and Shaffer in Clin Epidemiol 6:99-109, 2014 1; Henley et al. in Cancer Epidemiol Biomarkers Prev 24:1319-1326, 2015 2). The insidious nature and late presentation of this disease place it among the most lethal invasive neoplasms. Gallbladder cancer spreads early by lymphatic or hematogenous metastasis, as well as by direct invasion into the liver. While surgery may be curative at early stages, both surgical and nonsurgical treatments remain largely unsuccessful in patients with more advanced diseases (Rahman et al. in Cancer Med 6:874-880, 2017 3).

Obesity and Cancer: A Current Overview of Epidemiology, Pathogenesis, Outcomes, and Management

BACKGROUND

Obesity or excess body fat is a major global health challenge that has not only been associated with diabetes mellitus and cardiovascular disease but is also a major risk factor for the development of and mortality related to a subgroup of cancer. This review focuses on epidemiology, the relationship between obesity and the risk associated with the development and recurrence of cancer and the management of obesity.

METHODS

A literature search using PubMed and Google Scholar was performed and the keywords 'obesity' and cancer' were used. The search was limited to research papers published in English prior to September 2022 and focused on studies that investigated epidemiology, the pathogenesis of cancer, cancer incidence and the risk of recurrence, and the management of obesity.

RESULTS

About 4-8% of all cancers are attributed to obesity. Obesity is a risk factor for several major cancers, including post-menopausal breast, colorectal, endometrial, kidney, esophageal, pancreatic, liver, and gallbladder cancer. Excess body fat results in an approximately 17% increased risk of cancer-specific mortality. The relationship between obesity and the risk associated with the development of cancer and its recurrence is not fully understood and involves altered fatty acid metabolism, extracellular matrix remodeling, the secretion of adipokines and anabolic and sex hormones, immune dysregulation, and chronic inflammation. Obesity may also increase treatment-related adverse effects and influence treatment decisions regarding specific types of cancer therapy. Structured exercise in combination with dietary support and behavior therapy are effective interventions. Treatment with glucagon-like peptide-1 analogues and bariatric surgery result in more rapid weight loss and can be considered in selected cancer survivors.

CONCLUSIONS

Obesity increases cancer risk and mortality. Weight-reducing strategies in obesity-associated cancers are important interventions as a key component of cancer care. Future studies are warranted to further elucidate the complex relationship between obesity and cancer with the identification of targets for effective interventions.

The obesity paradox in patients with colorectal cancer: a systematic review and meta-analysis

CONTEXT

Obesity is widely regarded as an established risk factor for colorectal cancer (CRC). However, recent studies have shown that lower mortality and better cancer-specific survival were observed in CRC patients with elevated body mass index (BMI), an example of the obesity paradox, which is the inverse correlation between obesity and mortality in some populations.

OBJECTIVE

The aim of this systematic review and meta-analysis was to investigate the association between BMI and CRC outcomes.

DATA SOURCES

PubMed, Web of Science, MEDLINE, the Cochrane Library, and Embase databases were searched for relevant articles published from inception to December 31, 2020.

STUDY SELECTION

Studies comparing the prognosis of CRC patients with obesity or overweight with that of normal-weight CRC patients were eligible.

DATA EXTRACTION

Data were extracted by 2 reviewers independently; differences were resolved by a third reviewer. BMI was classified according to WHO categories.

DATA ANALYSIS

To assess the prognostic effects of different BMI categories in CRC patients, hazard ratios and 95%CIs of overall survival, disease-free survival, and cancer-specific survival were extracted from included articles.

RESULTS

Sixteen studies (55 391 patients in total) were included. Higher BMI was significantly associated with more favorable CRC outcomes. Compared with normal-weight patients, underweight patients had worse overall survival (HR = 1.26; 95%CI, 1.15-1.37) and disease-free survival (HR = 1.19; 95%CI, 1.11-1.27, while patients with overweight had better overall survival (HR = 0.92; 95%CI, 0.86-0.99), disease-free survival (HR = 0.96; 95%CI, 0.93-1.00), and cancer-specific survival (HR = 0.86; 95%CI, 0.76-0.98). Patients with morbid obesity had worse overall survival (HR = 1.12; 95%CI, 1.02-1.22) and disease-free survival (HR = 1.15; 95%CI, 1.07-1.24) than normal-weight patients. There was no significant difference in cancer-specific survival between patients with obesity (HR = 0.94; 95%CI, 0.76-1.16) and patients with normal weight, nor between patients with underweight and patients with normal weight (HR = 1.14; 95%CI, 0.82-1.58).

CONCLUSIONS

CRC patients with a higher BMI appear to have reduced mortality compared with normal-weight CRC patients, even though higher BMI/obesity is an established determinant for the development of CRC.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42020202320.

Obesity, Cancer, and Risk Reduction with Bariatric Surgery

The prevalence of noncommunicable diseases has increased dramatically in North America and throughout the world and is expected to continue increasing in coming years. Obesity has been linked to several types of cancers and is associated with increased morbidity and mortality following cancer diagnosis. Bariatric surgery has emerged as the prominent model to evaluate the effects of intentional weight loss on cancer incidence and outcomes. Current literature, comprising prospective cohort investigations, indicates site-specific reductions in cancer risk with select bariatric procedures. Future research is required to establish evidence-based indications for bariatric surgery in the context of cancer prevention.

Visceral Obesity, Metabolic Syndrome, and Esophageal Adenocarcinoma

Esophageal adenocarcinoma (EAC) represents an exemplar of obesity-associated carcinogenesis, with a progressive increase in EAC risk with increased body mass index. In this context, there is increased focus on visceral adipose tissue and associated metabolic dysfunction, including hypertension, diabetes mellitus and hyperlipidemia, or combinations of these in the metabolic syndrome. Visceral obesity (VO) may promote EAC via both directly impacting on gastro-esophageal reflux disease and Barrett's esophagus, as well as via reflux-independent effects, involving adipokines, growth factors, insulin resistance, and the microbiome. In this review these pathways are explored, including the impact of VO on the tumor microenvironment, and on cancer outcomes. The current evidence-based literature regarding the role of dietary, lifestyle, pharmacologic and surgical interventions to modulate the risk of EAC is explored.

Roles of Adipokines in Digestive Diseases: Markers of Inflammation, Metabolic Alteration and Disease Progression

Adipose tissue is a highly dynamic endocrine tissue and constitutes a central node in the interorgan crosstalk network through adipokines, which cause pleiotropic effects, including the modulation of angiogenesis, metabolism, and inflammation. Specifically, digestive cancers grow anatomically near adipose tissue. During their interaction with cancer cells, adipocytes are reprogrammed into cancer-associated adipocytes and secrete adipokines to affect tumor cells. Moreover, the liver is the central metabolic hub. Adipose tissue and the liver cooperatively regulate whole-body energy homeostasis via adipokines. Obesity, the excessive accumulation of adipose tissue due to hyperplasia and hypertrophy, is currently considered a global epidemic and is related to low-grade systemic inflammation characterized by altered adipokine regulation. Obesity-related digestive diseases, including gastroesophageal reflux disease, Barrett's esophagus, esophageal cancer, colon polyps and cancer, non-alcoholic fatty liver disease, viral hepatitis-related diseases, cholelithiasis, gallbladder cancer, cholangiocarcinoma, pancreatic cancer, and diabetes, might cause specific alterations in adipokine profiles. These patterns and associated bases potentially contribute to the identification of prognostic biomarkers and therapeutic approaches for the associated digestive diseases. This review highlights important findings about altered adipokine profiles relevant to digestive diseases, including hepatic, pancreatic, gastrointestinal, and biliary tract diseases, with a perspective on clinical implications and mechanistic explorations.

Obesity and Cancer Treatment Outcomes: Interpreting the Complex Evidence

A wealth of epidemiological evidence, combined with plausible biological mechanisms, present a convincing argument for a causal relationship between excess adiposity, commonly approximated as body mass index (BMI, kg/m²), and incident cancer risk. Beyond this relationship, there are a number of challenges posed in the context of interpreting whether being overweight (BMI 25.0-29.9 kg/m²) or obese (BMI ≥ 30.0 kg/m²) adversely influences disease progression, cancer mortality and survival. Elevated BMI (≥ 25.0 kg/m²) may influence treatment selection of, for example, the approach to surgery; the choice of chemotherapy dosing; the inclusion of patients into randomised clinical trials. Furthermore, the technical challenges posed by an elevated BMI may adversely affect surgical outcomes, for example, morbidity (increasing the risk of surgical site infections), reduced lymph node harvest (and subsequent risk of under-staging and under-treatment) and increased risk of margin positivity. Suboptimal chemotherapy dosing, associated with capping chemotherapy in obese patients as an attempt to avoid excess toxicity, might be a driver of poor prognostic outcomes. By contrast, the efficacy of immune checkpoint inhibition may be enhanced in patients who are obese, although in turn, this observation might be due to reverse causality. So, a central research question is whether being overweight or obese adversely affects outcomes either directly through effects of cancer biology or whether adverse outcomes are mediated through indirect pathways. A further dimension to this complex relationship is the obesity paradox, a phenomenon where being overweight or obese is associated with improved survival where the reverse is expected. In this overview, we describe a framework for evaluating methodological problems such as selection bias, confounding and reverse causality, which may contribute to spurious interpretations. Future studies will need to focus on prospective studies with well-considered methodology in order to improve the interpretation of causality.

Role of bariatric surgery in reducing the risk of colorectal cancer: a meta-analysis

BACKGROUND

Obesity increases the risk of multiple co-morbidities such as type 2 diabetes, cardiovascular disease and most cancers, including colorectal cancer. Currently, the literature presents conflicting results regarding the protective effects of bariatric surgery on the incidence of colorectal cancer. This meta-analysis was conducted to investigate the effect of bariatric surgery on the risk of developing colorectal cancer in obese individuals.

METHODS

Ovid Embase, Ovid MEDLINE, Cochrane CENTRAL and Web of Science were searched for relevant articles. Articles published by the end of December 2018 were retrieved; data were extracted according to evidence-based PICO (population, intervention, control, outcome) model and analysed using a random-effects model to estimate the pooled relative risk (RR) and its 95 per cent confidence interval. The heterogeneity of studies was tested and quantified using Cochran's Q and I² statistics. Meta-regression was used to investigate the association of year of study, region, mean length of follow-up and sample size with RR.

RESULTS

Seven articles, involving a total of 1 213 727 patients, were included in the meta-analysis. The pooled estimate of the RR was 0·64 (95 per cent c.i. 0·42 to 0·98). The test of asymmetry found no significant publication bias. Meta-regression showed that sample size was a statistically significant factor (P = 0·037), but year of publication, region and mean duration of follow-up were not significant.

CONCLUSION

Patients who underwent bariatric surgery had a greater than 35 per cent reduction in the risk of developing colorectal cancer compared with obese individuals who had no surgery.

Obesity and cancer risk: Emerging biological mechanisms and perspectives

Continuously rising trends in obesity-related malignancies render this disease spectrum a public health priority. Worldwide, the burden of cancer attributable to obesity, expressed as population attributable fraction, is 11.9% in men and 13.1% in women. There is convincing evidence that excess body weight is associated with an increased risk for cancer of at least 13 anatomic sites, including endometrial, esophageal, renal and pancreatic adenocarcinomas; hepatocellular carcinoma; gastric cardia cancer; meningioma; multiple myeloma; colorectal, postmenopausal breast, ovarian, gallbladder and thyroid cancers. We first synopsize current epidemiologic evidence; the obesity paradox in cancer risk and mortality; the role of weight gain and weight loss in the modulation of cancer risk; reliable somatometric indicators for obesity and cancer research; and gender differences in obesity related cancers. We critically summarize emerging biological mechanisms linking obesity to cancer encompassing insulin resistance and abnormalities of the IGF-I system and signaling; sex hormones biosynthesis and pathway; subclinical chronic low-grade inflammation and oxidative stress; alterations in adipokine pathophysiology; factors deriving from ectopic fat deposition; microenvironment and cellular perturbations including vascular perturbations, epithelial-mesenchymal transition, endoplasmic reticulum stress and migrating adipose progenitor cells; disruption of circadian rhythms; dietary nutrients; factors with potential significance such as the altered intestinal microbiome; and mechanic factors in obesity and cancer. Future perspectives regarding prevention, diagnosis and therapeutics are discussed. The aim of this review is to investigate how the interplay of these main potential mechanisms and risk factors, exerts their effects on target tissues provoking them to acquire a cancerous phenotype.

Body Size Indicators and Risk of Gallbladder Cancer: Pooled Analysis of Individual-Level Data from 19 Prospective Cohort Studies

Background: There are few established risk factors for gallbladder cancer beyond gallstones. Recent studies suggest a higher risk with high body mass index (BMI), an indicator of general heaviness, but evidence from other body size measures is lacking.Methods: Associations of adult BMI, young adult BMI, height, adult weight gain, waist circumference (WC), waist-height ratio (WHtR), hip circumference (HC), and waist-hip ratio (WHR) with gallbladder cancer risk were evaluated. Individual-level data from 1,878,801 participants in 19 prospective cohort studies (14 studies had circumference measures) were harmonized and included in this analysis. Multivariable Cox proportional hazards regression estimated hazard ratios (HR) and 95% confidence intervals (CI).Results: After enrollment, 567 gallbladder cancer cases were identified during 20.1 million person-years of observation, including 361 cases with WC measures. Higher adult BMI (per 5 kg/m2, HR: 1.24; 95% CI, 1.13-1.35), young adult BMI (per 5 kg/m2, HR: 1.12; 95% CI, 1.00-1.26), adult weight gain (per 5 kg, HR: 1.07; 95% CI, 1.02-1.12), height (per 5 cm, HR: 1.10; 95% CI, 1.03-1.17), WC (per 5 cm, HR: 1.09; 95% CI, 1.02-1.17), WHtR (per 0.1 unit, HR: 1.24; 95% CI, 1.00-1.54), and HC (per 5 cm, HR: 1.13; 95% CI, 1.04-1.22), but not WHR (per 0.1 unit, HR: 1.03; 95% CI, 0.87-1.22), were associated with higher risks of gallbladder cancer, and results did not differ meaningfully by sex or other demographic/lifestyle factors.Conclusions: These findings indicate that measures of overall and central excess body weight are associated with higher gallbladder cancer risks.Impact: Excess body weight is an important, and potentially preventable, gallbladder cancer risk factor. Cancer Epidemiol Biomarkers Prev; 26(4); 597-606. ©2017 AACR.

How to Manage the Obese Patient With Cancer

Purpose

Obesity (body mass index [BMI] ≥ 30 kg/m2) is common among patients with cancer. We reviewed management issues in the obese patient with cancer, focusing on how obesity influences treatment selection (including chemotherapy dosing), affects chemotherapy toxicity and surgical complications, and might be a treatment effect modifier.

Methods

The majority of evidence is drawn from observational studies and secondary analyses of trial data, typically analyzed in N × 3 BMI categories (normal weight, overweight, and obese) matrix structures. We propose a methodological framework for interpretation focusing on sample size and composition, nonlinearity, and unmeasured confounding.

Results

There is a common perception that obesity is associated with increased treatment-related toxicity. Accordingly, cytotoxic chemotherapy dose reduction is common in patients with elevated BMI. Contrary to this, there is some evidence that full dosing in obese patients does not result in increased toxicity. However, these data are from a limited number of regimens, and fail to fully capture cytotoxic drug pharmacodynamics and pharmacokinetic variability in obese patients. Among patients undergoing surgery, there is evidence that elevated BMI is associated with increased perioperative mortality and increased rates of infectious complications. A novel finding is that these relationships hold after surgery for malignancy, but not for benign indications. There are biologic plausibilities that obesity might be an effect modifier of treatment, but supporting evidence from clinical studies is inconsistent.

Conclusion

In line with the ASCO 2012 guidelines, chemotherapy dosing is probably best performed using actual body weight in obese patients. However, specific regimens known to be associated with increased toxicity in this group should be used with caution. There is no guidance on dose for obese patients treated with biologic agents. Currently, there are no specific recommendations for the surgical management of the obese patient with cancer.

Visceral adiposity and cancer survival: a review of imaging studies

Although obesity is a well-known risk factor for cancer, the association between obesity and cancer survival remains controversial. This is partially due to the inability of conventional obesity measures to directly assess adiposity or adipose tissue distribution. As a metabolic organ, visceral adipose tissue (VAT) secrets a variety of cytokines and cytokine-like factors, potentially affecting cancer survival. The objective of this review was to investigate the influence of imaging-assessed VAT on cancer survival. A total of 22 studies assessing the impact of visceral adiposity on survival were included. Negative associations between VAT and survival were more frequently observed among patients with colorectal (four of six studies) and pancreatic (three of five studies) cancers, compared to higher VAT predicting longer survival in most studies of renal cell carcinoma patients (four of five studies). Methodological limitations, including unstandardised VAT measurement methods, lack of other body composition measurement (i.e. muscle mass), small sample size and heterogeneous cohort characteristics, may explain controversial findings related to the impact of VAT on cancer survival.

Diagnosis and Management of Oesophageal Cancer in Bariatric Surgical Patients

BACKGROUND

Oesophageal cancer following bariatric surgery adds significant complexity to an already challenging disease. There is limited data on the diagnosis, presentation and management in these complex cases.

METHODS

A retrospective cohort study on prospectively collected data over 10 years was conducted. The oesophago-gastric cancer database was searched for patients with prior bariatric surgery. Data were retrieved on bariatric and cancer management.

RESULTS

We identified nine patients with oesophageal or gastro-oesophageal junction adenocarcinoma after bariatric surgery. Mean age was 58.3 ± 6.9 years, and duration from bariatric surgery was 13.2 ± 9.4 years. Weight loss at diagnosis was 30.6 ± 23.3 kg (excess weight loss 58.1 % ± 29.6). Modes of presentation were Barrett's surveillance (n = 3), reflux symptoms (n = 4) and incidental (n = 2). Management was surgical resection (n = 4), endoscopic mucosal resection (n = 2) and palliative (n = 3). Surgical resections were challenging due to adhesions, obesity, luminal dilatation and scarring on the stomach. There were two substantial leaks following gastroplasty.

CONCLUSIONS

Oesophageal cancer following bariatric surgery is a challenging problem, and surgical resection carries high risk. A high index of suspicion is required and symptoms investigated precipitously. Technical challenges of operating on obese patients and the specific effects of previous bariatric procedures need to be understood, particularly the limitations on reconstructive options.

The Obesity Paradox in Cancer: a Review

There is a common perception that excess adiposity, commonly approximated by body mass index (BMI), is associated with reduced cancer survival. A number of studies have emerged challenging this by demonstrating that overweight and early obese states are associated with improved survival. This finding is termed the "obesity paradox" and is well recognized in the cardio-metabolic literature but less so in oncology. Here, we summarize the epidemiological findings related to the obesity paradox in cancer. Our review highlights that many observations of the obesity paradox in cancer reflect methodological mechanisms including the crudeness of BMI as an obesity measure, confounding, detection bias, reverse causality, and a specific form of the selection bias, known as collider bias. It is imperative for the oncologist to interpret the observation of the obesity paradox against the above methodological framework and avoid the misinterpretation that being obese might be "good" or "protective" for cancer patients.

Sleep Apnea and Cancer: Analysis of a Nationwide Population Sample

STUDY OBJECTIVES

Epidemiological evidence from relatively small cohorts suggests that obstructive sleep apnea (OSA) is associated with higher cancer incidence and mortality. Here we aimed to determine whether cancer incidence for major cancer types and risk of metastases or mortality from cancer are increased in the presence of OSA.

METHODS

All OSA diagnoses included in an employee-sponsored health insurance database spanning the years 2003-2012 were identified and 1:1 matched demographically based on age, gender, and state of residence, or alternatively matched by comorbidities. The incidence of 12 types of cancer was assessed. In addition, another cohort of patients with a primary diagnosis of cancer was retrieved, and the risk of metastatic disease or cancer mortality was determined as a function of the presence or absence of OSA. Multivariate Cox proportional hazards regression models were fitted to assess the independent associations between OSA and outcomes of interest.

RESULTS

Based on a cohort of ∼5.6 million individuals, the incidence of all cancer diagnoses combined was similar in OSA and retrospectively matched cases. However, the adjusted risk of pancreatic and kidney cancer and melanoma were significantly higher in patients with OSA, while the risk of colorectal, breast, and prostate cancers appeared to be lower. Among individuals with a diagnosis of cancer, the presence of OSA was not associated with an increased risk for metastasis or death.

CONCLUSIONS

In a large nationally representative health insurance database, OSA appears to increase the risk for only a very selective number of cancer types, and does not appear to be associated with an increased risk of metastatic cancer or cancer-related deaths.

Impact of weight loss induced by gastric bypass or caloric restriction on oxidative stress and genomic damage in obese Zucker rats

BACKGROUND

Evidence on bariatric surgery induced weight loss and its possible impact on cancer risk is limited, but also controversial. We used obese Zucker(fa/fa) and lean Zucker(fa/+) to investigate the association between obesity, oxidative stress and genomic damage after weight loss induced either by Roux-en-Y gastric bypass surgery (RYGB) or caloric restriction.

METHODS

Male Zucker(fa/fa) rats underwent RYGB (n=15) or sham surgery (n=17). Five shams were food restricted and body weight matched (BWM) to RYGB. Twelve Zucker(fa/+) rats served as lean controls. Body weight and food intake were measured daily. An oral glucose tolerance test was performed on day 27. DHE staining and western blots of HSP70 and HO-1 were used to evaluate oxidative stress and anti-3-nitrotyrosine antibody staining for nitrative stress detection in colon and kidney. Lipid peroxidation products in urine were quantified by TBARS assay. LC/MS/MS was applied to measure urinary excretion of 8-oxoGua (oxidized DNA derived base), 8-oxodG (oxidized DNA derived nucleoside) and 8-oxoGuo (oxidized RNA derived nucleoside). DNA double strand breaks (DSBs) and cell proliferation (PCNA) were detected by immunohistochemistry.

RESULTS

Sham-operated rats showed impaired glucose tolerance, elevated plasma insulin levels as well as elevated oxidative stress and nitrative stress markers, which were less severe after weight loss by RYGB or caloric restriction. Cell proliferation showed similar trends but no significant alteration. DNA DSBs were more frequent in sham-operated compared to all other groups. DNA damage in Zucker(fa/fa) rats positively correlated with basal plasma insulin values (Spearman's correlation coefficient for colon, 0.634 and for kidney, 0.525).

CONCLUSIONS

RYGB and caloric restriction were sufficient to significantly reduce elevated oxidative/nitrative stress and genomic damage in obese Zucker(fa/fa) rats. Further investigations are needed to elucidate the underlying mechanism of these genome protective effects.

Gall Bladder Cancer

Gallbladder carcinoma (GBC) is the most common biliary epithelial malignancy, with an estimated 10,910 new cases and 3700 deaths per year (Siegel et al. in CA Cancer J Clin 65:5–29, 2015 [1]). This disease’s insidious nature and typically late presentation place it among the most lethal of invasive neoplasms. Gallbladder cancer spreads early by lymphatic or hematogenous metastasis and by direct invasion into the liver. While surgery may well be curative at early stages, both surgical and nonsurgical treatments remain largely unsuccessful in patients with more advanced disease.

Laparoscopic sleeve gastrectomy and gastroesophageal reflux

Bariatric surgery is the only effective procedure that provides long-term sustained weight loss. Sleeve gastrectomy (SG) has emerged over the last few years to be an ideal bariatric procedure because it has several advantages compared to more complex bariatric procedures, including avoiding an intestinal bypass. However, several published follow-up studies report an increased rate of gastroesophageal reflux (GERD) after a SG. GERD is described as either de novo or as being caused by aggravation of preexisting symptoms. However, the literature on this topic is ambivalent despite the potentially increased rate of GERDs that may occur after this common bariatric procedure. This article reviews the mechanisms responsible for GERD in obese subjects as well as the results after a SG with respect to GERD. Future directions for clinical research are discussed along with the current surgical options for morbidly obese patients with GERD and undergoing bariatric surgery.

Obesity and increased risk of esophageal adenocarcinoma

There has been a substantial increase in the incidence of esophageal adenocarcinoma over the past 40 years. Meta-analyses of large prospective cohorts and population-based case-control studies demonstrate consistent associations between obesity and the development of adenocarcinoma of the esophagus and esophago-gastric junction, with an approximate doubling of risk of esophageal adenocarcinoma among patients who are obese, and an almost five-fold increased risk among those with BMI >40 kg/m². The pathologic precursor, specialized intestinal metaplasia in Barrett's esophagus, is also associated with increased adiposity. Epidemiologic evidence suggests that this cancer risk is not solely due to increased gastro-esophageal reflux, and that adipose tissue itself, in particular visceral adipose, may fuel carcinogenesis through the production of adipokines, cytokines, growth factors, and increased inflammation. The robust epidemiologic evidence linking obesity with esophageal adenocarcinoma makes it an exemplar model for investigating the molecular mechanisms underpinning obesity-associated malignant progression, which are discussed in this review.

Adiposity and cancer risk: new mechanistic insights from epidemiology

Excess body adiposity, commonly expressed as body mass index (BMI), is a risk factor for many common adult cancers. Over the past decade, epidemiological data have shown that adiposity-cancer risk associations are specific for gender, site, geographical population, histological subtype and molecular phenotype. The biological mechanisms underpinning these associations are incompletely understood but need to take account of the specificities observed in epidemiology to better inform future prevention strategies.