Physical activity and the risk of Barrett's esophagus

Reframing How Physical Activity Reduces The Incidence of Clinically-Diagnosed Cancers: Appraising Exercise-Induced Immuno-Modulation As An Integral Mechanism

Undertaking a high volume of physical activity is associated with reduced risk of a broad range of clinically diagnosed cancers. These findings, which imply that physical activity induces physiological changes that avert or suppress neoplastic activity, are supported by preclinical intervention studies in rodents demonstrating that structured regular exercise commonly represses tumour growth. In Part 1 of this review, we summarise epidemiology and preclinical evidence linking physical activity or regular structured exercise with reduced cancer risk or tumour growth. Despite abundant evidence that physical activity commonly exerts anti-cancer effects, the mechanism(s)-of-action responsible for these beneficial outcomes is undefined and remains subject to ongoing speculation. In Part 2, we outline why altered immune regulation from physical activity - specifically to T cells - is likely an integral mechanism. We do this by first explaining how physical activity appears to modulate the cancer immunoediting process. In doing so, we highlight that augmented elimination of immunogenic cancer cells predominantly leads to the containment of cancers in a 'precancerous' or 'covert' equilibrium state, thus reducing the incidence of clinically diagnosed cancers among physically active individuals. In seeking to understand how physical activity might augment T cell function to avert cancer outgrowth, in Part 3 we appraise how physical activity affects the determinants of a successful T cell response against immunogenic cancer cells. Using the cancer immunogram as a basis for this evaluation, we assess the effects of physical activity on: (i) general T cell status in blood, (ii) T cell infiltration to tissues, (iii) presence of immune checkpoints associated with T cell exhaustion and anergy, (iv) presence of inflammatory inhibitors of T cells and (v) presence of metabolic inhibitors of T cells. The extent to which physical activity alters these determinants to reduce the risk of clinically diagnosed cancers - and whether physical activity changes these determinants in an interconnected or unrelated manner - is unresolved. Accordingly, we analyse how physical activity might alter each determinant, and we show how these changes may interconnect to explain how physical activity alters T cell regulation to prevent cancer outgrowth.

Lifestyle interventions can reduce the risk of Barrett's esophagus: a systematic review and meta-analysis of 62 studies involving 250,157 participants

Background

Barrett's esophagus (BE) is a well‐established risk factor for esophageal adenocarcinoma. Our objective was to investigate the effectiveness of lifestyle interventions on BE risk.

Methods

We searched PubMed, Embase, and Web of Science up to 30 September 2020. The summary relative risks (RRs) and 95% confidence intervals (CIs) for the highest versus lowest categories of exposure were assessed. Analyses of subgroup, dose–response, sensitivity, and publication bias were conducted.

Results

Sixty‐two studies were included that involved more than 250,157 participants and 22,608 cases. Seven lifestyle factors were investigated: smoking, alcohol, body mass index (BMI), physical activity, sleep time, medication, and diet. We observed statistically significant increased BE risks for smoking (RR = 1.35, 95% CI = 1.16–1.57), alcohol intake (RR = 1.23, 95% CI = 1.13–1.34), body fatness (RR = 1.08, 95% CI = 1.03–1.13), less sleep time (RR = 1.76, 95% CI = 1.24–2.49), and proton pump inhibitors use (RR = 1.64, 95% CI = 1.17–2.29). Reduced risks of BE were found for aspirin (RR = 0.70, 95% CI = 0.58–0.84) and the intake of vitamin C (RR = 0.59, 95% CI = 0.44–0.80), folate (RR = 0.47, 95% CI = 0.31–0.71), and fiber (RR = 0.95, 95% CI = 0.93–0.97). The quality of most included studies was high and the subgroup analysis according to the quality score showed significant results (p < 0.05). There was no publication bias for smoking and alcohol. Although the analysis suggested significant evidence of publication bias for BMI, sensitivity analysis showed that the changes in the recalculated RRs were not significant.

Conclusions

The large meta‐analysis revealed that lifestyle modifications could reduce the risks of BE and, consequently, esophageal adenocarcinoma.

Systematic assessment of environmental factors for gastroesophageal reflux disease: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

Side effects of long-term acid suppression have increased the scholars' interest in nonpharmacologic intervention.

AIMS

We summarized an umbrella review of the association between environmental factors and gastroesophageal reflux disease (GERD) and assessed their credibility.

METHODS

We appraised systematic reviews and meta-analyses. For each meta-analysis, we considered the effect size, 95% confidence interval, the heterogeneity, small-study effects, P-value for excess significance and largest study significant, then we graded the evidence according to Assessment of Multiple Systematic Reviews and the GRADE assessment.

RESULTS

23 publications met the inclusion criteria (13 meta-analyses and 10 systematic reviews), which evaluated 24 environmental factors. Among observational studies, we identified 7 risk factors: overweight/obesity [GERD/erosive esophagitis (EE)/GERD symptom], central adiposity [EE], smoking [GERD], alcohol [GERD/EE/non-erosive reflux disease (NERD)], NSAID [GERD], coffee [EE], Helicobacter pylori eradication [EE], and 1 protective factor: physical activity [GERD], this was based on a suggestive evidence of credibility. Across intervention studies, we identified 1 risk factor-Helicobacter pylori eradication [GERD] and 1 protective factor-breathing exercises [GERD], evidence for both was low grade.

CONCLUSIONS

We found varying levels of evidence for different environmental factors of GERD. None of them was proven to be convincing or highly recommended.

Association between physical activity and digestive-system cancer: An updated systematic review and meta-analysis

BACKGROUND

Physical activity (PA) may have an impact on digestive-system cancer (DSC) by improving insulin sensitivity and anticancer immune function and by reducing the exposure of the digestive tract to carcinogens by stimulating gastrointestinal motility, thus reducing transit time. The current study aimed to determine the effect of PA on different types of DSC via a systematic review and meta-analysis.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we searched for relevant studies in PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure. Using a random effects model, the relationship between PA and different types of DSC was analyzed.

RESULTS

The data used for meta-analysis were derived from 161 risk estimates in 47 studies involving 5,797,768 participants and 55,162 cases. We assessed the pooled associations between high vs. low PA levels and the risk of DSC (risk ratio (RR)  = 0.82, 95% confidence interval (95%CI): 0.79-0.85), colon cancer (RR = 0.81, 95%CI: 0.76-0.87), rectal cancer (RR = 0.88, 95%CI: 0.80-0.98), colorectal cancer (RR = 0.77, 95%CI: 0.69-0.85), gallbladder cancer (RR = 0.79, 95%CI: 0.64-0.98), gastric cancer (RR = 0.83, 95%CI: 0.76-0.91), liver cancer (RR = 0.73, 0.60-0.89), oropharyngeal cancer (RR = 0.79, 95%CI: 0.72-0.87), and pancreatic cancer (RR = 0.85, 95%CI: 0.78-0.93). The findings were comparable between case-control studies (RR = 0.73, 95%CI: 0.68-0.78) and prospective cohort studies (RR = 0.88, 95%CI: 0.80-0.91). The meta-analysis of 9 studies reporting low, moderate, and high PA levels, with 17 risk estimates, showed that compared to low PA, moderate PA may also reduce the risk of DSC (RR = 0.89, 95%CI: 0.80-1.00), while compared to moderate PA, high PA seemed to slightly increase the risk of DSC, although the results were not statistically significant (RR = 1.11, 95%CI: 0.94-1.32). In addition, limited evidence from 5 studies suggested that meeting the international PA guidelines might not significantly reduce the risk of DSC (RR = 0.96, 95%CI: 0.91-1.02).

CONCLUSION

Compared to previous research, this systematic review has provided more comprehensive information about the inverse relationship between PA and DSC risk. The updated evidence from the current meta-analysis indicates that a moderate-to-high PA level is a common protective factor that can significantly lower the overall risk of DSC. However, the reduction rate for specific cancers may vary. In addition, limited evidence suggests that meeting the international PA guidelines might not significantly reduce the risk of DSC. Thus, future studies must be conducted to determine the optimal dosage, frequency, intensity, and duration of PA required to reduce DSC risk effectively.

Helicobacter pylori infection reduces the risk of Barrett's esophagus: A meta-analysis and systematic review

INTRODUCTION

The prevalence of Helicobacter pylori infection (HPI) has been decreasing in developed countries, with an increasing prevalence of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC) at the same time. The aim of our meta-analysis was to quantify the risk of BE in the context of HPI.

METHODS

A systematic search was conducted in 3 databases for studies on BE with data on prevalence of HPI from inception until December 2016. Odds ratios for BE in HPI were calculated by the random effects model with subgroup analyses for geographical location, presence of dysplasia in BE, and length of the BE segment.

RESULTS

Seventy-two studies were included in the meta-analysis, including 84 717 BE cases and 390 749 controls. The overall analysis showed that HPI reduces the risk of BE; OR = 0.68 (95% CI: 0.58-0.79, P < .001). Subgroup analyses revealed risk reduction in Asia OR = 0.53 (95% CI: 0.33-0.84, P = .007), Australia OR = 0.56 (95% CI: 0.39-0.80, P = .002), Europe OR = 0.77 (95% CI: 0.60-0.98, P = .035), and North-America OR = 0.59 (95% CI: 0.47-0.74, P < .001). The risk was significantly reduced for dysplastic BE, OR = 0.37 (95% CI: 0.26-0.51, P < .001) for non-dysplastic BE, OR = 0.51 (95% CI: 0.35-0.75, P = .001), and for long segment BE, OR = 0.25 (95% CI: 0.11-0.59, P = .001) in case of HPI.

CONCLUSIONS

This extensive meta-analysis provides additional evidence that HPI is associated with reduced risk of BE. Subgroup analyses confirmed that this risk reduction is independent of geographical location. HPI is associated with significantly lower risk of dysplastic, non-dysplastic, and long segment BE.

The association between physical activity and the risk of symptomatic Barrett's oesophagus: a UK prospective cohort study

BACKGROUND

Physical activity affects the functioning of the gastrointestinal system through both local and systemic effects and may play an important role in the aetiology of gastroesophageal reflux disease, Barrett's oesophagus and oesophageal adenocarcinoma. We investigated, for the first time in a large prospective cohort study, associations between recreational and occupational levels of physical activity and the incidence of Barrett's oesophagus.

PARTICIPANTS AND METHODS

The European Prospective Investigation of Cancer-Norfolk recruited 30 445 men and women between 1993 and 1997. Occupational and recreational levels of physical activity were measured using a baseline questionnaire. The cohort was followed up until 2015 to identify symptomatic cases of Barrett's oesophagus. Cox proportional hazard regression estimated hazard ratios (HR) for physical activity and the development of disease.

RESULTS

Two hundred and three participants developed Barrett's oesophagus (mean age: 70.6 years) the majority of whom were men (70.9%). There was an inverse association between standing occupations and disease risk [HR: 0.50, 95% confidence interval (CI): 0.31-0.82, P=0.006] when compared with sedentary jobs. Heavy manual occupations were positively associated with disease risk (HR: 1.66, 95% CI: 0.91-3.00), but conventional statistical significance was not reached (P=0.09). No associations were found between recreational activity and the risk of Barrett's oesophagus (HR: 1.34, 95% CI: 0.72-2.50, P=0.35, highest vs. lowest levels of activity).

CONCLUSION

Our study suggests that occupational levels of physical activity may be associated with the risk Barrett's oesophagus. However, further work is required to confirm and describe specific occupations that may be protective.

Does physical activity protect against the development of gastroesophageal reflux disease, Barrett's esophagus, and esophageal adenocarcinoma? A review of the literature with a meta-analysis

Physical activity affects the functioning of the gastrointestinal system through both local and systemic effects and may play an important role in reducing the risk of esophageal adenocarcinoma. This review assesses the biological mechanisms and epidemiological evidence for the relationship between physical activity and the development of esophageal adenocarcinoma and its precursor diseases: gastroesophageal reflux disease (GORD) and Barrett's esophagus. A search of PubMed, Medline, Embase, and CINAHL was conducted from their inceptions to 25th March 2017 for analytical studies that examined associations between recreational and/or occupational levels of physical activity and the risk of GORD, Barrett's esophagus, and esophageal adenocarcinoma. Where appropriate, a meta-analysis of effects was undertaken. Seven studies were included (2 cohort, 5 case control). For GORD, there were three case-control studies with 10 200 cases among 78 034 participants, with a pooled estimated OR of 0.67 (95% CI 0.57-0.78) for high versus low levels of recreational physical activity. In Barrett's esophagus, there was a single case-control study, which reported no association, OR 1.19 (95% CI 0.82-1.73). For esophageal adenocarcinoma, there were three studies (two prospective cohort, one case control) with 666 cases among 910 376 participants. The largest cohort study reported an inverse association for high versus low levels of recreational physical activity, RR 0.68, 95% CI 0.48-0.96. The remaining two studies reported no associations with either occupational or combined recreational and occupational activity. Heterogeneity in the measurement of exposure (recreational, occupational, and both) made a pooled estimate for esophageal adenocarcinoma inappropriate. Although limited, there is some evidence that higher levels of recreational physical activity may reduce the risk of both GORD and esophageal adenocarcinoma, but further large cohort studies examining the type, intensity and duration of activities that may be beneficial are needed.