Association of Physical Activity and Sedentary Behavior With the Risk of Colorectal Cancer

Causal associations between dietary factors and colorectal cancer risk: a Mendelian randomization study

Background

Previous epidemiological studies have found a link between colorectal cancer (CRC) and human dietary habits. However, the inherent limitations and inevitable confounding factors of the observational studies may lead to the inaccurate and doubtful results. The causality of dietary factors to CRC remains elusive.

Methods

We conducted two-sample Mendelian randomization (MR) analyses utilizing the data sets from the IEU Open GWAS project. The exposure datasets included alcoholic drinks per week, processed meat intake, beef intake, poultry intake, oily fish intake, non-oily fish intake, lamb/mutton intake, pork intake, cheese intake, bread intake, tea intake, coffee intake, cooked vegetable intake, cereal intake, fresh fruit intake, salad/raw vegetable intake, and dried fruit intake. In our MR analyses, the inverse variance weighted (IVW) method was employed as the primary analytical approach. The weighted median, MR-Egger, weighted mode, and simple mode were also applied to quality control. Heterogeneity and pleiotropic analyses were implemented to replenish the accuracy of the results.

Results

MR consequences revealed that alcoholic drinks per week [odds ratio (OR): 1.565, 95% confidence interval (CI): 1.068-2.293, p = 0.022], non-oily fish intake (OR: 0.286; 95% CI: 0.095-0.860; p = 0.026), fresh fruit intake (OR: 0.513; 95% CI: 0.273-0.964; p = 0.038), cereal intake (OR: 0.435; 95% CI: 0.253-0.476; p = 0.003) and dried fruit intake (OR: 0.522; 95% CI: 0.311-0.875; p = 0.014) was causally correlated with the risk of CRC. No other significant relationships were obtained. The sensitivity analyses proposed the absence of heterogeneity or pleiotropy, demonstrating the reliability of the MR results.

Conclusion

This study indicated that alcoholic drinks were associated with an increased risk of CRC, while non-oily fish intake, fresh fruit intake, cereal intake, and dried fruit were associated with a decreased risk of CRC. This study also indicated that other dietary factors included in this research were not associated with CRC. The current study is the first to establish the link between comprehensive diet-related factors and CRC at the genetic level, offering novel clues for interpreting the genetic etiology of CRC and replenishing new perspectives for the clinical practice of gastrointestinal disease prevention.

Metabolic Interaction Between Host and the Gut Microbiota During High-Fat Diet-Induced Colorectal Cancer

Colorectal cancer (CRC) is the second-highest cause of cancer-associated mortality among both men and women worldwide. One of the risk factors for CRC is obesity, which is correlated with a high-fat diet prevalent in Western dietary habits. The association between an obesogenic high-fat diet and CRC has been established for several decades; however, the mechanisms by which a high-fat diet increases the risk of CRC remain unclear. Recent studies indicate that gut microbiota strongly influence the pathogenesis of both high-fat diet-induced obesity and CRC. The gut microbiota is composed of hundreds of bacterial species, some of which are implicated in CRC. In particular, the expansion of facultative anaerobic Enterobacteriaceae, which is considered a microbial signature of intestinal microbiota functional imbalance (dysbiosis), is associated with both high-fat diet-induced obesity and CRC. Here, we review the interaction between the gut microbiome and its metabolic byproducts in the context of colorectal cancer (CRC) during high-fat diet-induced obesity. In addition, we will cover how a high-fat diet can drive the expansion of genotoxin-producing Escherichia coli by altering intestinal epithelial cell metabolism during gut inflammation conditions.

Association between circadian physical activity patterns and cancer incidence through regulation of inflammation: A UK biobank study

BACKGROUND

Physical activity (PA) has been linked with cancer incidence. However, the effects and mechanisms underpinning circadian PA trajectories on cancer remain elusive. This study aimed to explore the optimal PA patterns in reducing cancer incidence and the associated potential mediators.

METHODS

Between 2006 and 2010, 502,400 participants were recruited from the UK Biobank. Out of these, 102,323 participants wore accelerometers, which allowed for collecting acceleration data continuously over 7 days. After excluding participants with previous cancer history, 96,687 participants were included in K-means cluster analysis to identify PA trajectories. The association between PA and cancer incidence was assessed using Cox regression analysis. Additionally, we investigated the mediating role of inflammation.

RESULTS

A total of 5995 cancer cases were recorded during a median follow-up of 7.1 years. Four distinct PA trajectories (persistent low, single peak, double peak, and vigorous) were identified. The ideal PA patterns reduced the risk of 7 out of 17 site-specific cancers, with the lowest hazard ratios and 95% confidence intervals of cancer for bladder (0.59, 0.40-0.86), breast (0.73, 0.60-0.89), kidney (0.45, 0.26-0.78), lung (0.59, 0.41-0.84), myeloma (0.49, 0.27-0.88), and oral & pharynx (0.51, 0.26-0.98) in the vigorous pattern and for colorectal (0.71, 0.54-0.93) in the double peak pattern. Moreover, the mediating effects of inflammation were significant.

CONCLUSION

Optimal PA trajectories reduced cancer incidence, especially in double peak and vigorous patterns. The protective effect was associated with both intensity and circadian rhythm. Crucially, this protection was mediated by inflammation regulation.

Green space exposure and colorectal cancer: A systematic review

Green space has been linked to colorectal cancer, but the evidence is still limited and inconclusive. This review aimed to investigate the relationship between green space and CRC. The studies were searched using three primary journal databases: PubMed, Scopus, and Web of Science. The retrieved citations were screened, and data from articles about GS exposure and CRC were extracted. The Newcastle-Ottawa Quality Assessment Form for Cohort Studies was used to evaluate the studies' quality. Five of the 1792 articles identified were eligible for the final review, which included five cohort studies published between 2017 and 2022. Each one article from the United States, the United Kingdom, France, Belgium, and Germany and All studies are of high quality. Four studies reported CRC incidence and one study reported CRC mortality from GS exposure. There was no significant association between GS attributes (Normalized Difference Vegetation Index (NDVI), surrounding greenness, surrounding green area, proximity to GS (agricultural lands, urban GSs, and forests), and count of recreational facilities and parks) with CRC. Only one study discovered that a healthier ecosystem was linked to a lower CRC risk. Although the evidence is still limited, the findings may indicate the presence of other factors in the relationship between GS and CRC. Future research should continue to focus on the variation of GS and the factors that influence it. Specific attention to the development of GS has the potential to produce benefits while mitigating cancer risk.

The role of exercise in obesity-related cancers: Current evidence and biological mechanisms

Cancer ranks among the five leading causes of death in almost all countries and has important repercussions for individual and public health, the healthcare system, and society in general. Obesity increases the incidence of many types of cancer, but growing evidence suggests that physical activity may decrease risk for developing a variety of obesity-related cancer types, and, in some cases, may improve cancer prognosis and mortality rates. This review summarizes recent evidence on the effect of physical activity on obesity-related cancer prevention and survival. For some cancers, including breast, colorectal, and endometrial cancer, there is strong evidence for a preventative effect of exercise, but for many others, including gallbladder and kidney cancer, and multiple myeloma, evidence is inconsistent or largely lacking. Though many potential mechanisms have been proposed to explain the onco-protective effect of exercise, including improved insulin sensitivity, alterations in sex hormone availability, improved immune function and inflammation, myokine secretion, and modulation of intracellular signaling at the level of AMP kinase, the exact mechanism(s) of action within each cancer subtype remains poorly defined. Overall, a deeper understanding of how exercise can help against cancer and of the exercise parameters that can be altered to optimize exercise prescription is necessary and should be the subject of future investigation.

Physical Activity and Sedentary Time in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutritional Examination Survey

Several recent studies suggested reduced physical activity (PA) related to the COVID-19 pandemic without consensus. This study investigated the changes in PA and sedentary time during the COVID-19 pandemic compared to before the COVID-19 era. The Korea National Health and Nutrition Examination Survey 2019 and 2020 were used. The ≥19-year-old population was examined in 2019 and 2020 for time spent engaging in high- and moderate-intensity PA and sedentary time. Based on the recommended level of PA by the World Health Organization, ≥75 min/wk of high PA and ≥150 min/of moderate PA were classified. A sedentary time of ≥120 min/d was selected. Multiple logistic regression analysis with complex sampling was conducted for ≥75 min/wk of high PA, ≥150 min/wk of moderate PA, and ≥120 min/d of sedentary time in the 2020 group compared to the 2019 group. The ≥75 min/wk high PA was not lower in the 2020 group than in the 2019 group (adjusted odds ratio (aOR) = 0.96, 95% confidence intervals (95% CIs) = 0.79–1.18, P = 0.696). The ≥150 min/wk of moderate PA was also not lower in the 2020 group (aOR = 1.12, 95% CI = 0.94–1.32, p = 0.201). However, the ≥150 min/wk of moderate PA in the female group was higher in the 2020 group than in the 2019 group (aOR = 1.29, 95% CI = 1.01–1.65, p = 0.042). Sedentary time ≥ 120 min/d was lower in the 2020 group (aOR = 0.35, 95% CI = 0.17–0.72, p = 0.005). This association was consistent in the 19–39-year-old and female group. In conclusion, during the COVID-19 pandemic, high and moderate PA were not decreased in Korean adults, while sedentary time was reduced.