Infection, antibiotic therapy and risk of colorectal cancer: a nationwide nested case-control study in patients with Type 2 diabetes mellitus

Association between the antibiotics use and recurrence in patients with resected colorectal cancer: EVADER-1, a nation-wide pharmaco-epidemiologic study

BACKGROUND

The impact of antibiotics (ATBs) on the risk of colorectal cancer (CRC) recurrence after curative resection remains unknown.

METHODS

Using the French nation-wide database of cancer patients, all newly diagnosed non-metastatic CRC patients resected between 01/2012 and 12/2014 were included. The perioperative ATB intake (from 6 months before surgery until 1 year after) was classified according to the class, the period of use (pre- vs post-resection), the disease stage (localized and locally advanced), and the primary tumor location (colon and rectum/junction). The primary endpoint was the 3-year disease-free survival (DFS). The impact of ATB was assessed using time-dependent multivariate Cox models.

RESULTS

A total of 35,496 CRC patients were included. Seventy-nine percent of patients had at least one ATB intake. Outpatient ATB intake after surgery was associated with unfavorable 3-year DFS. The ATBs associated with decreased 3-year DFS were cephalosporins, streptogramins, quinolones, penicillin A with beta-lactamase inhibitors, and antifungals with differential effects according to the primary tumor location and disease stage.

CONCLUSION

These findings suggest that ATBs modulate the risk of recurrence after early CRC resection with a differential impact of the ATB classes depending on disease stage and tumor site.

The Potential of Clostridium butyricum to Preserve Gut Health, and to Mitigate Non-AIDS Comorbidities in People Living with HIV

A dramatic reduction in mortality among people living with HIV (PLWH) has been achieved during the modern antiretroviral therapy (ART) era. However, ART does not restore gut barrier function even after long-term viral suppression, allowing microbial products to enter the systemic blood circulation and induce chronic immune activation. In PLWH, a chronic state of systemic inflammation exists and persists, which increases the risk of development of inflammation-associated non-AIDS comorbidities such as metabolic disorders, cardiovascular diseases, and cancer. Clostridium butyricum is a human butyrate-producing symbiont present in the gut microbiome. Convergent evidence has demonstrated favorable effects of C. butyricum for gastrointestinal health, including maintenance of the structural and functional integrity of the gut barrier, inhibition of pathogenic bacteria within the intestine, and reduction of microbial translocation. Moreover, C. butyricum supplementation has been observed to have a positive effect on various inflammation-related diseases such as diabetes, ulcerative colitis, and cancer, which are also recognized as non-AIDS comorbidities associated with epithelial gut damage. There is currently scant published research in the literature, focusing on the influence of C. butyricum in the gut of PLWH. In this hypothesis review, we speculate the use of C. butyricum as a probiotic oral supplementation may well emerge as a potential future synergistic adjunctive strategy in PLWH, in tandem with ART, to restore and consolidate intestinal barrier integrity, repair the leaky gut, prevent microbial translocation from the gut, and reduce both gut and systemic inflammation, with the ultimate objective of decreasing the risk for development of non-AIDS comorbidities in PLWH.

Antibiotics use and risk of colorectal neoplasia: An updated meta-analysis

PURPOSE

Accumulating evidence indicate that antibiotic use could induce microbiome dysbiosis, which was a critical driver to the onset and progression of colorectal cancer (CRC). But the relationship between antibiotics use and CRC was still disputed. Hence, we conducted this systematic review and meta-analysis to appraise and synthesize the present available evidence to clarify the association.

METHODS

PubMed, Embase, Web of Science, and Cochrane Library were systematically searched for relevant observational studies from inception to June 5, 2020. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to explore the association between antibiotics use and CRC using random-effects model. Subgroup analyses, sensitive analyses, and publication bias were conducted to assess the robust reliability of pooled results.

RESULTS

A total of 15 observational studies containing 5,164,138 patients were included in this meta-analysis. The pooled analysis indicated that the total antibiotic use was correlated with increased risk of CRC (OR, 1.11; 95% CI, 1.05-1.18). The subgroup analyses suggested that antibiotic use significantly elevated risk of colon cancer, but not rectal cancer. Furthermore, we found that penicillin, cephalosporin, anti-anaerobic, and anti-aerobic antibiotics increased the risk of CRC, in particular metronidazole but no significant associations were identified in macrolide, tetracycline, sulfonamides, nitrofurans, and quinolone use. The results of sensitive analyses and publication bias indicated the conclusions were robust.

CONCLUSION

The findings showed that antibiotics use may be associated with the onset of CRC. Policy-makers and clinicians should adequately assess possible benefits and harms of antibiotics use, especially in some high-risk populations. Also, for high-risk patients with previous antibiotics use, it was suggested to perform early colonoscopy screening to find or even eliminate early-stage CRC.

Anti-cancer activity of human gastrointestinal bacteria

Malignant neoplasm is one of the most incurable diseases among inflammatory diseases. Researchers have been studying for decades to win over this lethal disease and provide the light of hope to humankind. The gastrointestinal bacteria of human hold a complex ecosystem and maintain homeostasis. One hundred trillion microbes are residing in the gastrointestinal tract of human. Disturbances in the microbiota of human's gastrointestinal tract can create immune response against inflammation and also can develop diseases, including cancer. The bacteria of the gastrointestinal tract of human can secrete a variety of metabolites and bioproducts which aid in the preservation of homeostasis in the host and gut. During pathogenic dysbiosis, on the other hand, numerous microbiota subpopulations may increase and create excessive levels of toxins, which can cause inflammation and cancer. Furthermore, the immune system of host and the epithelium cell can be influenced by gut microbiota. Probiotics, which are bacteria that live in the gut, have been protected against tumor formation. Probiotics are now studied to see if they can help fight dysbiosis in cancer patients undergoing chemotherapy or radiotherapy because of their capacity to maintain gut homeostasis. Countless numbers of gut bacteria have demonstrated anti-cancer efficiency in cancer treatment, prevention, and boosting the efficiency of immunotherapy. The review article has briefly explained the anti-cancer immunity of gut microbes and their application in treating a variety of cancer. This review paper also highlights the pre-clinical studies of probiotics against cancer and the completed and ongoing clinical trials on cancers with the two most common and highly effective probiotics Lactobacillus and Bacillus spp.

Antimicrobial drug use and the risk of glioma: A case-control study

BACKGROUND

The use of antibiotics has been associated with increased risks of various cancers. Comprehensive information on the association of antibiotic use with the risk of glioma is lacking.

METHODS

We performed a large case-control study based on the Clinical Practice Research Datalink (CPRD) GOLD from the United Kingdom. We identified 4423 glioma cases recorded between 1995 and 2020 and matched them to controls (1:10) on the date of diagnosis (i.e., the index date), age, sex, general practice, and number of years of medical history in the database prior to the index date. We conducted conditional logistic regression analyses to calculate odds ratios (ORs) with 95% confidence intervals (CIs). The exposures of interest were the use of antimicrobial drugs, including antibacterial, antiviral, antifungal, antiprotozoal, and anthelmintic drugs with specific subclasses, where possible.

RESULTS

We found no substantially increased risk of glioma after ever-use of antibiotics (OR 1.13, 95% CI 1.03-1.24). The risk did not increase with the increasing number of prescriptions received or with increasing time from first use to cancer diagnosis. The use of polyenes was associated with a weakly decreased risk of glioma (OR 0.81, 95% CI 0.67-0.96).

Vitamin D intake as well as circulating 25-hydroxyvitamin D level and risk for the incidence and recurrence of colorectal cancer precursors: A meta-analysis

Objective

Vitamin D consumption and circulating 25(OH)D level are associated with decreased risk of colorectal cancer (CRC) and colorectal adenoma (CRA), but few studies have assessed their relationship with the incidence and recurrence of CRC precursors. Therefore, we performed this meta-analysis to further evaluate the association.

Methods

We searched PubMed, Web of Science, Scopus and Embase databases in English until August 2021. Studies evaluating the association of vitamin D intake and circulating 25(OH)D level with risk of CRC precursors were included. A random-effects model was used to pool the risk estimates.

Results

A total of 48 studies were selected for inclusion. The CRC precursors incidence was negatively correlated with total vitamin D intake (RR = 0.84 95%CI: 0.80–0.88) and circulating 25(OH)D level (RR = 0.79 95%CI: 0.67–0.92). However, vitamin D intake and circulating 25(OH)D level did not show significant effects on the risk of CRC precursors recurrence. For dose-response analysis, evidence of a linear association was found between CRC precursors incidence and circulating 25(OH)D level, and the risk decreased by 14% per 10 ng/ml increment of circulating 25(OH)D level (RR = 0.86 95% CI: 0.75–0.99).

Conclusion

Vitamin D intake and circulating 25(OH)D level can play an effective role in reducing the risk of incidence of CRC precursors. However, they have not prevented the recurrence of CRC precursors.

Adaptation of Bacteria to Antineoplastic Agents Involves Persister Cells and Increases Resistance to Antibiotics

The increasing number of life-threatening infections observed in cancer patients has been ascribed to chemotherapy-induced neutropenia and to invasive medical procedures such as surgery and the application of catheters. In this study, it was questioned if the infections could also be favored by an increased resistance of bacteria due to the adaptation to antineoplastic agents used in chemotherapy. After exposure to several antineoplastic agents, it was observed that cells of Staphylococcus aureus, Mycobacterium vaccae, Pseudomonas aeruginosa, and Escherichia coli changed the fatty acid profile of their cellular membranes, produced exopolymeric substances, and formed aggregates that adhered to surfaces. Additionally, when exposed to high concentrations of these compounds, a persister sub-population could be identified. After adaptation to antineoplastic agents, the minimum inhibitory concentration (MIC) of several antibiotics increased considerably in the tested strains.

Association between antibiotic consumption and colon and rectal cancer development in older individuals: A territory-wide study

Background

Antibiotics may alter colorectal cancer (CRC) risk due to gut dysbiosis. We aimed to study the specific and temporal effects of various antibiotics on CRC development in older individuals.

Methods

This was a territory‐wide retrospective cohort study. Subjects aged 60 years and older who did not have CRC diagnosed on screening/diagnostic colonoscopy diagnosed between 2005 and 2013 were recruited. Exclusion criteria were history of CRC, colectomy, inflammatory bowel disease, and CRC diagnosed within 6 months of index colonoscopy. Exposure was use of any antibiotics up to 5 years before colonoscopy. The primary outcomes were CRC diagnosed >6 m after colonoscopy. Covariates were patient demographics, history of colonic polyps/polypectomy, concomitant medication use (NSAIDs, COX‐2 inhibitors, aspirin, and statins), and performance of endoscopy centers (colonoscopy volume and polypectomy rate). Stratified analysis was conducted according to nature of antibiotics and location of cancer.

Results

Ninety seven thousand one hundred and sixty‐two eligible subjects (with 1026 [1.0%] cases of CRC) were identified, 58,704 (60.4%) of whom were exposed to antibiotics before index colonoscopy. Use of antibiotics was associated with a lower risk of cancer in rectum (adjusted hazard ratio [aHR]: 0.64, 95% CI: 0.54–0.76), but a higher risk of cancer in proximal colon (aHR: 1.63, 95%CI: 1.15–2.32). These effects differed as regards the anti‐anaerobic/anti‐aerobic activity, narrow‐/broad‐spectrum, and administration route of antibiotics.

Conclusions

Antibiotics had divergent effects on CRC development in older subjects, which varied according to the location of cancer, antibiotic class, and administration route.

Oral antibiotic use and early-onset colorectal cancer: findings from a case-control study using a national clinical database

BACKGROUND

Antibiotic-induced gut dysbiosis has been associated with colorectal cancer (CRC) in older adults. This study will investigate whether an association exists between antibiotic usage and early-onset colorectal cancer (CRC), and also evaluate this in later-onset CRC for comparison.

METHODS

A case-control study was conducted using primary care data from 1999-2011. Analysis were conducted separately in early-onset CRC cases (diagnosed < 50 years) and later-onset cases (diagnosed ≥ 50 years). Conditional logistic regression was used to calculate odds ratios and 95% confidence intervals (CI) for the associations between antibiotic exposure and CRC by tumour location, adjusting for comorbidities.

RESULTS

Seven thousands nine hundred and three CRC cases (445 aged <50 years) and 30,418 controls were identified. Antibiotic consumption was associated with colon cancer in both age-groups, particularly in the early-onset CRC cohort (<50 years: adjusted Odds Ratio (ORadj) 1.49 (95% CI 1.07, 2.07), p = 0·018; ≥50 years (ORadj (95% CI) 1.09 (1.01, 1.18), p = 0·029). Antibiotics were not associated with rectal cancer (<50 years: ORadj (95% CI) 1.17 (0.75, 1.84), p = 0.493; ≥50 years: ORadj (95% CI) 1.07 (0.96, 1.19), p = 0.238).

CONCLUSION

Our findings suggest antibiotics may have a role in colon tumour formation across all age-groups.

Butyrate-producing human gut symbiont, Clostridium butyricum, and its role in health and disease

Clostridium butyricum is a butyrate-producing human gut symbiont that has been safely used as a probiotic for decades. C. butyricum strains have been investigated for potential protective or ameliorative effects in a wide range of human diseases, including gut-acquired infection, intestinal injury, irritable bowel syndrome, inflammatory bowel disease, neurodegenerative disease, metabolic disease, and colorectal cancer. In this review we summarize the studies on C. butyricum supplementation with special attention to proposed mechanisms for the associated health benefits and the supporting experimental evidence. These mechanisms center on molecular signals (especially butyrate) as well as immunological signals in the digestive system that cascade well beyond the gut to the liver, adipose tissue, brain, and more. The safety of probiotic C. butyricum strains appears well-established. We identify areas where additional human randomized controlled trials would provide valuable further data related to the strains' utility as an intervention.

An evolutionary explanation for antibiotics’ association with increased colon cancer risk

 

More than 10 studies have confirmed the association of antibiotic overuse with colorectal cancer. The exact cause is unknown, but most authors hypothesize that disturbance of colon microbiota is the main culprit. In this commentary, an evolutionary explanation is proposed. It is well known that antibiotics can induce antibiotic resistance in bacteria through selection of mutators—DNA mismatch repair deficient (dMMR) strains. Mutators have an increased survival potential due to their high mutagenesis rate. Antibiotics can also cause stress in human cells. Selection of dMMR colon cells may be advantageous under this stress, mimicking selection of bacterial mutators. Concomitantly, mismatch repair deficiency is a common cause of cancer, this may explain the increased cancer risk after multiple cycles of oral antibiotics. This proposed rationale is described in detail, along with supporting evidence from the peer-reviewed literature and suggestions for testing hypothesis validity. Treatment schemes could be re-evaluated, considering toxicity and somatic selection mechanisms.

Lay Summary

The association of antibiotics with colon cancer is well established but of unknown cause. Under an evolutionary framework, antibiotics may select for stress-resistant cancerous cells that lack mechanisms for DNA mismatch repair (MMR). This mimics the selection of antibiotic resistant ‘mutators’—MMR-deficient micro-organisms—highly adaptive due to their increased mutagenesis rate.

Species-Level Analysis of the Human Gut Microbiome Shows Antibiotic Resistance Genes Associated With Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer deaths and continuously increases new cancer cases globally. Accumulating evidence links risks of CRC to antibiotic use. Long-term use and abuse of antibiotics increase the resistance of the gut microbiota; however, whether CRC is associated with antibiotic resistance in gut microbiota is still unclear. In this study, we performed a de novo assembly to metagenomic sequences in 382 CRC patients and 387 healthy controls to obtain representative species-level genome bins (rSGBs) and plasmids and analyzed the abundance variation of species and antibiotic resistance genes (ARGs). Twenty-five species and 65 ARGs were significantly enriched in the CRC patients, and among these ARGs, 12 were multidrug-resistant genes (MRGs), which mainly included acrB, TolC, marA, H-NS, Escherichia coli acrR mutation, and AcrS. These MRGs could confer resistance to fluoroquinolones, tetracyclines, cephalosporins, and rifamycin antibiotics by antibiotic efflux and inactivation. A classification model was built using the abundance of species and ARGs and achieved areas under the curve of 0.831 and 0.715, respectively. Our investigation has identified the antibiotic resistance types of ARGs and suggested that E. coli is the primary antibiotic resistance reservoir of ARGs in CRC patients, providing valuable evidence for selecting appropriate antibiotics in the CRC treatment.

Use of antibiotics and colorectal cancer risk: a primary care nested case-control study in Belgium

OBJECTIVES

To examine the association between the use of oral antibiotics and subsequent colorectal cancer risk.

DESIGN

Matched case-control study.

SETTING

General practice centres participating in the Integrated Computerised Network database in Flanders, Belgium.

PARTICIPANTS

In total, 1705 cases of colorectal cancer diagnosed between 01 January 2010 and 31 December 2015 were matched to 6749 controls by age, sex, comorbidity and general practice centre.

PRIMARY OUTCOME MEASURE

The association between the number of prescriptions for oral antibiotics and the incidence of colorectal cancer over a period of 1-10 years, estimated by a conditional logistic regression model.

RESULTS

A significantly increased risk of colorectal cancer (OR 1.25, 95% CI 1.10 to 1.44) was found in subjects with one or more prescriptions compared with those with none after correction for diabetes mellitus. No dose-response relationship was found.

CONCLUSIONS

This study resulted in a modestly higher risk of having colorectal cancer diagnosed after antibiotic exposure. The main limitation was missing data on known risk factors, in particular smoking behaviour. This study did not allow us to examine the causality of the relationship, indicating the need of further investigation.

Bacteriophage manipulation of the microbiome associated with tumour microenvironments-can this improve cancer therapeutic response?

Some cancer treatment failures have been attributed to the tumour microbiota, with implications that microbiota manipulation may improve treatment efficacy. While antibiotics have been used to control bacterial growth, their dysbiotic effects on the microbiome, failure to penetrate biofilms and decreased efficacy due to increasing antimicrobial resistance by bacteria, suggest alternatives are needed. Bacteriophages may provide a precise means for targeting oncobacteria whose relative abundance is increased in tumour tissue microbiomes. Fusobacterium, Streptococcus, Peptostreptococcus, Prevotella, Parvimonas, and Treponema species are prevalent in tumour tissue microbiomes of some cancers. They may promote cancer growth by dampening immunity, stimulating release of proinflammatory cytokines, and directly interacting with cancer cells to stimulate proliferation. Lytic bacteriophages against some of these oncobacteria have been isolated and characterised. The search continues for others. The possibility exists for their testing as adjuncts to complement existing therapies. In this review, we highlight the role of oncobacteria, specifically those whose relative abundance in the intra-tumour microbiome is increased, and discuss the potential for bacteriophages against these micro-organisms to augment existing cancer therapies. The capacity for bacteriophages to modulate immunity and kill specific bacteria makes them suitable candidates to manipulate the tumour microbiome and negate the effects of these oncobacteria.

Antibiotics Use and Subsequent Risk of Colorectal Cancer: A Swedish Nationwide Population-Based Study

Background

Antibiotics use may increase colorectal cancer (CRC) risk by altering the gut microbiota, with suggestive evidence reported. Our study aims to investigate antibiotics use in relation to subsequent CRC risk.

Methods

This is a nationwide, population-based study with a matched case-control design (first primary CRC cases and 5 matched, cancer-free controls). Complete-population data, extracted from Swedish national registers for the period 2005-2016, were used to calculate odds ratios and 95% confidence intervals.

Results

We included 40 545 CRC cases and 202 720 controls. Using the full dataset, we found a positive association between more frequent antibiotics use and CRC, excluding antibiotics prescribed within 2 years of diagnosis attenuated results toward the null. In site-specific analyses, excluding the 2-year washout, the positive association was confined to the proximal colon (adjusted odds ratio for very high use vs no use = 1.17, 95% confidence interval = 1.05 to 1.31). For rectal cancer, an inverse association, which appears to be driven by women, was observed. Quinolones and sulfonamides and/or trimethoprims were positively associated with proximal colon cancer, whereas a more general inverse association, across antibiotics classes, was observed for rectal cancer. We found no association between methenamine hippurate, a urinary tract antiseptic not affecting the gut microbiota, and CRC risk.

Conclusions

This register-based study covering the entire population of Sweden found a robust association between antibiotics use and higher risk of proximal colon cancer and an inverse association with rectal cancer in women. This study strengthens the evidence from previous investigations and adds important insight into site-specific colorectal carcinogenesis.

Early-life antibiotic use and risk of attention-deficit hyperactivity disorder and autism spectrum disorder: results of a discordant twin study

Background

Development of the gut-brain axis in early life may be disturbed by antibiotic use. It has been hypothesized that this disturbance may contribute to development of neurodevelopmental disorders, including autism spectrum disorder and attention-deficit hyperactivity disorder. We aimed to assess the association between antibiotic use in early life and the risk of developing attention-deficit hyperactivity disorder or autism spectrum disorder, while controlling for shared genetic and environmental factors in a discordant twin design.

Methods

We conducted a cohort study in twins (7–12 years; 25 781 twins) from the Netherlands Twin Register (NTR) and a replication study in the Childhood and Adolescent Twin Study in Sweden (CATSS; 7946 9-year-old twins). Antibiotic use was recorded before age 2 years. Attention-deficit hyperactivity disorder and autism spectrum disorder were parent-reported in the Netherlands Twin Register and register-based in the Childhood and Adolescent Twin Study in Sweden.

Results

Early-life antibiotic use was associated with increased risk of attention-deficit hyperactivity disorder development [pooled odds ratio (OR) 1.10, 95% confidence interval (CI) 1.02-1.17] and autism spectrum disorder (pooled OR 1.15, 95% CI 1.06-1.25) in a case-control design. When restricting to monozygotic twin pairs discordant for the outcome, associations disappeared for both disorders in both cohorts (attention-deficit hyperactivity disorder OR 0.90, 95% CI 0.48-1.69 and OR 0.80, 95% CI 0.37-1.76, and autism spectrum disorder OR 0.66, 95% CI 0.38-1.16 and OR 0.29, 95% CI 0.02-4.50, respectively).

Conclusions

Our findings suggest that the association between early-life antibiotic use and risk of attention-deficit hyperactivity and autism spectrum disorder may be confounded by shared familial environment and genetics.

Antibiotic Use Associated With Risk of Colorectal Polyps in a Nationwide Study

BACKGROUND & AIMS

Use of antibiotics affects the composition of the microbiome and might affect development of colorectal polyps, which are precursors to colorectal cancer.

METHODS

We performed a nested case-control study in Sweden of 45,744 patients with a colorectal polyp (cases) in the nationwide gastrointestinal ESPRESSO histopathology cohort, using unaffected full siblings as controls (n = 93,307). Polyps were classified by morphology SnoMed codes into conventional adenomas and serrated polyps. Through linkage to the Prescribed Drug Register, we assessed use and cumulative dispensations of antibiotic until 1 year prior to polyp diagnosis for cases and their sibling controls.

RESULTS

During a median study period of 6.9 years, compared with non-users, users of antibiotics (including 28,884 cases [63.1%] and 53,222 sibling controls [57.0%]) had a higher risk of colorectal polyps (odds ratio [OR], 1.08; 95% CI, 1.04-1.13). Risk increased with higher number of dispensations (OR for ≥ 6 dispensations, 1.33; 95% CI, 1.25-1.43) (Ptrend < .0001). We observed a stronger association with polyps for broad-spectrum antibiotics (OR comparing users to non-users, 1.23; 95% CI, 1.18-1.29) than for narrow-spectrum antibiotics (OR, 1.05; 95% CI, 1.01-1.10), and for tetracyclines and quinolones (OR, 1.21) than penicillin and other classes (ORs ranged from 1.04 to 1.16). The findings remained robust with several sensitivity analyses, including use of a 2-year lead-in period for antibiotic assessment and correction for misclassification in controls. Use of broad-spectrum antibiotics was more strongly associated with risk of serrated polyps (OR, 1.29; 95% CI, 1.21-1.38) compared with risk of conventional adenomas (OR, 1.17; 95% CI, 1.11-1.24). We found no differences in risk of colon vs rectal polyps with antibiotic use (Pheterogeneity > .10). We found stronger associations for younger (<50 years) vs older adults (≥50 years) for users of quinolones, sulfonamides, trimethoprim, and cephalosporins (Pinteraction < .001).

CONCLUSIONS

In a nationwide case-control study in Sweden, after accounting for hereditary and early life environmental factors, antibiotic use was associated with increased risk of colorectal polyps. Our findings indicate a role for intestinal dysbiosis in early stages of colorectal carcinogenesis.

Antibiotic use and colorectal neoplasia: a systematic review and meta-analysis

Background and aims

Colorectal cancer (CRC) is the third most common cancer for women and men and the second leading cause of cancer death in the USA. There is emerging evidence that the gut microbiome plays a role in CRC development, and antibiotics are one of the most common exposures that can alter the gut microbiome. We performed a systematic review and meta-analysis to characterise the association between antibiotic use and colorectal neoplasia.

Methods

We searched PubMed, EMBASE, and Web of Science for articles that examined the association between antibiotic exposure and colorectal neoplasia (cancer or adenoma) through 15 December 2019. A total of 6031 citations were identified and 6 papers were included in the final analysis. We assessed the association between the level of antibiotic use (defined as number of courses or duration of therapy) and colorectal neoplasia using a random effects model.

Results

Six studies provided 16 estimates of the association between level of antibiotic use and colorectal neoplasia. Individuals with the highest levels of antibiotic exposure had a 10% higher risk of colorectal neoplasia than those with the lowest exposure (effect size: 1.10, 95% CI 1.01 to 1.18). We found evidence of high heterogeneity (I²=79%, p=0.0001) but not of publication bias.

Conclusions

Higher levels of antibiotic exposure is associated with an increased risk of colorectal neoplasia. Given the widespread use of antibiotics in childhood and early adulthood, additional research to further characterise this relationship is needed.

Dairy Consumption and Risk of Conventional and Serrated Precursors of Colorectal Cancer: A Systematic Review and Meta-Analysis of Observational Studies

Objective

The consumption of dairy is associated with decreased risk of colorectal cancer (CRC), but few studies have assessed the relationship between dairy consumption and precursors of CRC. Therefore, we performed the first meta-analysis to further evaluate this association.

Methods

PubMed, Embase, Scopus, and Web of Science databases were searched through July 2020 for observational studies. Study-specific risk estimates for the highest versus lowest category were pooled using the random-effects and fixed-effects model. The methodological quality of included studies was assessed using the ROBINS-I Scale.

Results

A total of 12 studies were included (3 cohort studies and 9 case-control studies). Compared with the lowest level consumption, fermented dairy products had a decreased risk of precursors of CRC in both cohort (RR = 0.92 95% CI: 0.87–0.97) and case-control studies (RR = 0.98 95% CI: 0.96–0.99). Total dairy (RR = 0.80 95% CI: 0.68–0.96) and cheese (RR = 0.96 95% CI: 0.93–0.99) consumption was inversely associated with the risk in case-control studies whereas yogurt consumption was inversely associated with the risk in cohort studies (RR = 0.91 95%CI: 0.86–0.96). No significant associations were found for consumption of total milk and non/low-fat milk. For dose-response analyses, evidence of linear association was found in total dairy and yogurt consumption. The risk decreased by 12% for an increment of 200 g/d total dairy consumption (RR = 0.88 95% CI: 0.81–0.95) and decreased by 8% for an increment of 50 g/d yogurt consumption (RR = 0.92 95% CI: 0.85–0.99).

Conclusions

Fermented dairy products, specifically yogurt and cheese, were significantly associated with decreased risk of conventional and serrated precursors of colorectal cancer.

Consumption of sugar-sweetened beverages and fruit juice and human cancer: a systematic review and dose-response meta-analysis of observational studies

Background: Several epidemiological studies have assessed the association of sugary drinks consumption with cancer, but the results remain controversial. Objective: We performed this analysis to evaluate possible causal relationship between sugary drinks consumption and cancer risk and mortality. Methods: We searched PubMed, Embase, and Web of Science databases in English. Observational studies evaluating the association of sugary drinks intake with cancer were included. Random-effects meta-analysis was used to calculate the risk estimates. Results: A total of 71 observational articles with 32 case-control and 39 cohort studies were included in the meta-analysis. 60 addressed cancer risk, and 11 reported cancer mortality. Compared with the lowest level, the highest level of sugar-sweetened beverages (SSB) consumption showed an increased overall cancer risk (RR=1.12 95% CI: 1.06-1.19, P=0.000) and mortality (RR=1.07 95% CI: 1.01-1.14, P=0.029), and fruit juice intake showed a positive association with cancer risk in cohort studies (RR=1.06 95% CI: 1.01-1.11, P=0.013). Subgroup analyses based on cancer type indicated that risk of breast cancer, hepatocellular carcinoma, colorectal cancer, and prostatic cancer mortality had a positive association with SSB consumption. For dose-response analysis, evidence of a linear association was found between overall cancer risk and SSB or fruit juice consumption, and the risk increase by 4% for one servings/d increment in SSB intake and 14% in fruit juice. Conclusions: Our findings suggest the consumption of sugary beverages may increase the risk and mortality of cancer, especially risk of breast cancer, hepatocellular carcinoma, colorectal cancer, and prostatic cancer, and mortality of breast cancer, though the evidence was limited.

Antibiotic use and risk of colorectal cancer: a systematic review and dose-response meta-analysis

BACKGROUND

It is understudied whether the posed association of oral antibiotics with colorectal cancer (CRC) varies between antibiotic spectrums, colorectal continuum, and if a non-linear dose-dependent relationship is present.

DESIGN

Three electronic databases and a trial platform were searched for all relevant studies, from inception until February 2020, without restrictions. Random-effects meta-analyses provided pooled effect-sizes (ES) with 95% confidence intervals (CI). Dose-response analyses modelling the relationship between number of days exposed to antibiotics and CRC risk were extended to non-linear multivariable random-effects models.

RESULTS

Of 6483 identified publications ten were eligible, including 4.1 million individuals and over 73,550 CRC cases. The pooled CRC risk was increased among individuals who ever-used antibiotics (ES = 1.17, 95%CI 1.05-1.30), particularly for broad-spectrum antibiotics (ES = 1.70, 95%CI 1.26-2.30), but not for narrow-spectrum antibiotic (ES = 1.11, 95% 0.93-1.32). The dose-response analysis did not provide strong evidence of any particular dose-response association, and the risk patterns were rather similar for colon and rectal cancer.

DISCUSSION

The antibiotic use associated CRC risk seemingly differs between broad- and narrow-spectrum antibiotics, and possibly within the colorectal continuum. It remains unclear whether this association is causal, requiring more mechanistic studies and further clarification of drug-microbiome interactions.

Antibiotics, cancer risk and oncologic treatment efficacy: a practical review of the literature

Antibiotics have been extensively used to treat infectious diseases over the past century and have largely contributed to increased life expectancy over time. However, antibiotic use can impose profound and protracted changes to the diversity of the microbial ecosystem, affecting the composition of up to 30% of the bacterial species in the gut microbiome. By modifying human microbiota composition, antibiotics alter the action of several oncologic drugs, potentially leading to decreased efficacy and increased toxicities. Whether antibiotics interfere with cancer therapies or even increase the risk of cancer development has been under investigation, and no randomised trials have been conducted so far. The aim of the current review is to describe the possible effects of antibiotic therapies on different oncologic treatments, especially immunotherapies, and to explore the link between previous antibiotics use and the development of cancer.

Is antibiotics use really associated with increased risk of colorectal cancer? An updated systematic review and meta-analysis of observational studies

PURPOSE

The association between antibiotics and colorectal cancer (CRC) risk has drawn increasing attention but remains controversial. This study was performed to clarify the association.

METHODS

A systematic review and meta-analysis was performed on seven electronic databases. The pooled odds ratios (OR) with a 95% confidence interval (CI) were calculated to estimate the association using the fixed-effects model or the random-effects model.

RESULTS

Ten studies that contained 4,853,289 participants were included in our study. We found that antibiotics use was associated with a higher risk of CRC (OR 1.09, 95%CI 1.02-1.17, I² = 92.8%). More than 60 days of antibiotics use and 5 prescriptions of antibiotics were significantly associated with a higher risk of CRC. Sub-analysis on different types of antibiotics found that anti-anaerobic antibiotics, penicillins, and quinolones use led to increased risk of CRC (OR 1.22, 95% CI 1.04-1.44, I² = 89.1%; OR 1.09, 95% CI 1.04-1.13, I² = 69.2%; OR 1.15, 95% CI 1.03-1.35, I² = 88.2%; respectively) and colon cancer (OR 1.28, 95% CI 1.04-1.58, I² = 98.5%; OR 1.09, 95% CI 1.05-1.12, I² = 0; OR 1.09, 95% CI 1.04-1.15, I² = 0; respectively). However, antibiotics use was not significantly associated with rectal cancer (OR 1.03, 95% CI 0.92-1.16, I² = 77.6%).

CONCLUSION

It needs attention that antibiotics use is associated with a higher risk of CRC, especially for colon cancer. Clinicians should be aware of the potential risk of CRC when prescribing anti-anaerobic antibiotics, penicillins, and quinolones in the future. Further studies are needed to assess any potential differences by tumor sites and class of antibiotics.

Antibiotic exposure and the risk of colorectal adenoma and carcinoma: a systematic review and meta-analysis of observational studies

AIM

The Incidence of colorectal cancer (CRC) is increasing, and evidence suggests that maladaptation of the bowel microbiome may be associated with colorectal carcinogenesis. Consumption of antibiotics may cause imbalance of the bowel microbiome but research assessing an association between antibiotic exposure and CRC is inconsistent. The aim of this systematic review and meta-analysis was to appraise and synthesize the available evidence.

METHOD

The MEDLINE, EMBASE and CINAHL databases were searched for published observational studies. We included eight studies of 3 408 312 patients. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the odds of CRC following antibiotic exposure were estimated. Sensitivity analyses were performed according to exposure definition, study design and risk of bias.

RESULTS

A weak association between antibiotic exposure and CRC was demonstrated when exposure was assessed cumulatively by the number of prescriptions (OR 1.204, 95% CI 1.097-1.322, P < 0.001) or duration of antibiotic exposure (OR 1.168, 95% CI 1.087-1.256, P < 0.001). Antibiotic exposure assessed as a binary variable demonstrated no association with CRC.

CONCLUSION

The findings suggest a weak association between cumulative antibiotic consumption and risk of CRC but no causal conclusions can be made. Limitations include the heterogeneity and quality of the available research, particularly with regard to measurement of antibiotic exposure.

Oral antibiotic use and chronic disease: long-term health impact beyond antimicrobial resistance and Clostridioides difficile

We recently reported an increased colon cancer risk associated with oral antibiotic use in a large United Kingdom population. This association between antibiotic exposure and cancer risk adds to a growing body of evidence that antibiotic use has unintended off-target long-term health consequences. This addendum highlights major studies linking antibiotic use and chronic disease in pediatric and adult populations. Microbiota dysbiosis is the key proposed mechanism underlying antibiotic:disease associations, resulting in alterations in gene expression, epigenetic modification, colonization by pathogenic bacteria, instigation of biofilms, and immune regulation and inflammation. These adverse outcomes of antibiotic exposure underscore the need for diagnostic and antibiotic stewardship, as well as the urgency for further development of non-antibiotic therapies for bacterial infections.

Therapeutic Efficacy Evaluation of Pegylated Liposome Encapsulated With Vinorelbine Plus 111In Repeated Treatments in Human Colorectal Carcinoma With Multimodalities of Molecular Imaging

BACKGROUND/AIM

In precision therapy, liposomal encapsulated chemotherapeutic drugs have been developed to treat cancers by achieving higher drug accumulation in the tumor compared to normal tissues/organs.

MATERIALS AND METHODS

We developed a novel chemoradiotherapeutic approach via nanoliposomes conjugated with vinorelbine (VNB) and ¹¹¹In (¹¹¹In-VNB-liposome) and examined their pharmacokinetics, biodistribution, maximum tolerance dose, and toxicity in a NOD/SCID mouse model.

RESULTS

Pharmacokinetic results showed that the area under the curve (AUC) of PEGylated liposomes was about 17-fold higher than that of the free radioisotope. Tumor growth inhibition by ¹¹¹In-VNB-liposome was significantly higher than that of the control (p<0.05).

CONCLUSION

The tumors in NOD/SCID mice bearing HT-29/tk-luc xenografts were significantly suppressed by ¹¹¹In-VNB-liposomes. The study proposed repeated treatments with a novel liposome-mediated radiochemotherapy and validation of therapeutic efficacy via imaging.

Early-onset colorectal cancer: initial clues and current views

Over the past several decades, the incidence of early-onset colorectal cancer (EOCRC; in patients <50 years old) has increased at an alarming rate. Although robust and scientifically rigorous epidemiological studies have sifted out environmental elements linked to EOCRC, our knowledge of the causes and mechanisms of this disease is far from complete. Here, we highlight potential risk factors and putative mechanisms that drive EOCRC and suggest likely areas for fruitful research. In addition, we identify inconsistencies in the evidence implicating a strong effect of increased adiposity and suggest that certain behaviours (such as diet and stress) might place nonobese and otherwise healthy people at risk of this disease. Key risk factors are reviewed, including the global westernization of diets (usually involving a high intake of red and processed meats, high-fructose corn syrup and unhealthy cooking methods), stress, antibiotics, synthetic food dyes, monosodium glutamate, titanium dioxide, and physical inactivity and/or sedentary behaviour. The gut microbiota is probably at the crossroads of these risk factors and EOCRC. The time course of the disease and the fact that relevant exposures probably occur in childhood raise important methodological issues that are also discussed.

The Role of the Gut Microbiome in Colorectal Cancer Development and Therapy Response

Colorectal cancer (CRC) is the third most common cancer worldwide and the leading cause of cancer-related deaths. Recently, several studies have demonstrated that gut microbiota can alter CRC susceptibility and progression by modulating mechanisms such as inflammation and DNA damage, and by producing metabolites involved in tumor progression or suppression. Dysbiosis of gut microbiota has been observed in patients with CRC, with a decrease in commensal bacterial species (butyrate-producing bacteria) and an enrichment of detrimental bacterial populations (pro-inflammatory opportunistic pathogens). CRC is characterized by altered production of bacterial metabolites directly involved in cancer metabolism including short-chain fatty acids and polyamines. Emerging evidence suggests that diet has an important impact on the risk of CRC development. The intake of high-fiber diets and the supplementation of diet with polyunsaturated fatty acids, polyphenols and probiotics, which are known to regulate gut microbiota, could be not only a potential mechanism for the reduction of CRC risk in a primary prevention setting, but may also be important to enhance the response to cancer therapy when used as adjuvant to conventional treatment for CRC. Therefore, a personalized modulation of the pattern of gut microbiome by diet may be a promising approach to prevent the development and progression of CRC and to improve the efficacy of antitumoral therapy.

Outcomes of metastatic colorectal cancer patients in relationship to prior and concurrent antibiotics use; individual patient data analysis of three clinical trials

BACKGROUND

Antibiotic use at the time of chemotherapy has been linked with inferior outcomes among a number of solid tumors. The current study aims at further assessing this observation among metastatic colorectal cancer patients treated with first-line systemic chemotherapy.

METHODS

This is a pooled analysis of three clinical trial datasets (NCT00384176; NCT00272051; NCT00305188) that were accessed from the Project Data Sphere platform. Kaplan-Meier survival estimates were used to evaluate the impact of antibiotic use on overall and progression-free survival and multivariable Cox regression models were employed to further assess this impact.

RESULTS

A total of 1446 patients were included in the current analysis. These include 108 patients who received antibiotics before the start of chemotherapy, 499 patients who received antibiotics after the start of chemotherapy, and 839 patients who did not receive antibiotics. Using Kaplan-Meier survival estimates, the use of antibiotics prior to the start of chemotherapy was associated with worse progression-free (P = 0.001) and overall survival (P < 0.001). Likewise, when multivariable Cox regression analyses were conducted, prior antibiotic use is associated with worse progression-free (HR for antibiotic use during chemotherapy versus antibiotic use prior to chemotherapy = 0.764; 95% CI 0.604-0.966; P = 0.024) and overall survival (HR for antibiotic use during chemotherapy versus antibiotic use prior to chemotherapy = 0.710; 95% CI 0.537-0.940; P = 0.017).

CONCLUSION

Antibiotic use before (but not following) the start of 5FU-based chemotherapy is associated with worse progression-free and overall survival among patients with metastatic colorectal cancer.

Association Between Anti-bacterial Drug Use and Digestive System Neoplasms: A Systematic Review and Meta-analysis

Background: Anti-bacterial drugs are thought to be associated with several malignancies. Objective: We conducted a systematic review and meta-analysis to assess the association between antibacterial drug exposure and the risk of digestive system neoplasms. Methods: Relevant publications reporting a relationship between antibiotic use and the risk of cancer were identified in PubMed, EMBASE, and Cochrane Central Register through June 2018. The random-effects model was selected to pool the risk ratios (RRs) and determine 95% confidence intervals (95% CIs). We performed subgroup analyses by tumor organ site, individual antibacterial drug class, and drug dose accumulation. Results: A total of 17 eligible studies (four randomized trials and 13 observational studies) involving 77,284 cancer patients were included in our analyses. Anti-bacterial drug exposure slightly increased the risk of overall digestive system cancer (RR, 1.12; 95% CI, 1.10-1.14), stomach and small intestine (RR, 1.12; 95% CI, 1.07-1.17), anorectocolonic (RR, 1.08; 95% CI, 1.05-1.12), and hepatobiliary and pancreatic cancers (RR, 1.18; 95% CI, 1.14-1.22). For different anti-bacterial drugs classes, nitroimidazoles (RR, 1.17; 95% CI, 1.09-1.26) and quinolones (RR, 1.18; 95% CI, 1.11-1.26) showed a modest association with the risk of cancers incidence. The risks of digestive system cancers increased with the rise of drug dose accumulation: low (RR, 1.08; 95% CI, 1.05-1.11), intermediate (RR, 1.15; 95% CI, 1.12-1.18), and high (RR, 1.22; 95% CI, 1.18-1.26). Conclusions: Anti-bacterial drug exposure was associated with the risks of digestive system cancer occurrence in our analysis.

Oral antibiotic use and risk of colorectal cancer in the United Kingdom, 1989-2012: a matched case-control study

BACKGROUND

Microbiome dysbiosis predisposes to colorectal cancer (CRC), but a population-based study of oral antibiotic exposure and risk patterns is lacking.

OBJECTIVE

To assess the association between oral antibiotic use and CRC risk.

DESIGN

A matched case-control study (incident CRC cases and up to five matched controls) was performed using the Clinical Practice Research Datalink from 1989 to 2012.

RESULTS

28 980 CRC cases and 137 077 controls were identified. Oral antibiotic use was associated with CRC risk, but effects differed by anatomical location. Antibiotic use increased the risk of colon cancer in a dose-dependent fashion (p_trend <0.001). The risk was observed after minimal use, and was greatest in the proximal colon and with antibiotics with anti-anaerobic activity. In contrast, an inverse association was detected between antibiotic use and rectal cancers (p_trend=0.003), particularly with length of antibiotic exposure >60 days (adjusted OR (aOR), 0.85, 95% CI 0.79 to 0.93) as compared with no antibiotic exposure. Penicillins, particularly ampicillin/amoxicillin increased the risk of colon cancer (aOR=1.09 (1.05 to 1.13)), whereas tetracyclines reduced the risk of rectal cancer (aOR=0.90 (0.84 to 0.97)). Significant interactions were detected between antibiotic use and tumour location (colon vs rectum, p_interaction<0.001; proximal colon versus distal colon, p_interaction=0.019). The antibiotic-cancer association was found for antibiotic exposure occurring >10 years before diagnosis (aOR=1.17 (1.06 to 1.31)).

CONCLUSION

Oral antibiotic use is associated with an increased risk of colon cancer but a reduced risk of rectal cancer. This effect heterogeneity may suggest differences in gut microbiota and carcinogenesis mechanisms along the lower intestinal tract.

Use of Antibiotics and Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies

The association between antibiotic use and risk of cancer development is unclear, and clinical trials are lacking. We performed a systematic review and meta-analysis of observational studies to assess the association between antibiotic use and risk of cancer. PubMed, the Cochrane Library and EMBASE were searched from inception to 24 February 2019 for studies reporting antibiotic use and subsequent risk of cancer. We included observational studies of adult subjects with previous exposure to antibiotics and available information on incident cancer diagnoses. For each of the eligible studies, data were collected by three reviewers. Risk of cancer was pooled to provide an adjusted odds ratio (OR) with a 95% confidence interval (CI). The primary outcome was the risk of developing cancer in ever versus non-antibiotic users. Cancer risk’s association with antibiotic intake was evaluated among 7,947,270 participants (n = 25 studies). Overall, antibiotic use was an independent risk factor for cancer occurrence (OR 1.18, 95%CI 1.12–1.24, p < 0.001). The risk was especially increased for lung cancer (OR 1.29, 95%CI 1.03–1.61, p = 0.02), lymphomas (OR 1.31, 95%CI 1.13–1.51, p < 0.001), pancreatic cancer (OR 1.28, 95%CI 1.04–1.57, p = 0.019), renal cell carcinoma (OR 1.28, 95%CI 1.1–1.5, p = 0.001), and multiple myeloma (OR 1.36, 95%CI 1.18–1.56, p < 0.001). There is moderate evidence that excessive or prolonged use of antibiotics during a person’s life is associated with slight increased risk of various cancers. The message is potentially important for public health policies because minimizing improper antibiotic use within a program of antibiotic stewardship could also reduce cancer incidence.

Antibiotics and immunotherapy in gastrointestinal tumors: Friend or foe?

The incidence of gastrointestinal (GI) tumors is increasing year by year, and its pathogenesis is closely related to the intestinal flora. At present, the use of antibiotics is very common in the clinic. And cancer patients with low immunity are vulnerable to all sorts of infections, such as respiratory tract infections and urinary tract infections. Moreover, cancer patients easily run into fever and neutropenia induced by myelosuppression. Therefore, antibiotics are used extensively and even overused in many conditions. However, because of the special anatomical location of the gastrointestinal tract, the antibiotic usage will bring changes to the intestinal flora. Besides, with the expanding popularity of immunotherapy, various factors affecting the efficacy of immune checkpoint inhibitors (ICIs) have been extensively explored, including cancer-associated inflammation and the local and systemic factors that lead to immunosuppression. Some biomarkers for ICIs, including the expression of PD-L1, tumor mutation load, and microbiota, also have been investigated, and many studies have confirmed that gut microbiota can affect the efficacy of immunotherapy. But further studies on the influence of antibiotics directly on immunotherapy are rare. In this review, we discuss the relationship between GI tumors and antibiotics, the current status of immunotherapy in GI tumors, and the influence of antibiotics on immunotherapy.

Fecal microbiota transplantation in cancer management: Current status and perspectives

The human gut is home to a large and diverse microbial community, comprising about 1,000 bacterial species. The gut microbiota exists in a symbiotic relationship with its host, playing a decisive role in the host's nutrition, immunity and metabolism. Accumulating studies have revealed the associations between gut dysbiosis or some special bacteria and various cancers. Emerging data suggest that gut microbiota can modulate the effectiveness of cancer therapies, especially immunotherapy. Manipulating the microbial populations with therapeutic intent has become a hot topic of cancer research, and the most dramatic manipulation of gut microbiota refers to fecal microbiota transplantation (FMT) from healthy individuals to patients. FMT has demonstrated remarkable clinical efficacy against Clostridium difficile infection (CDI) and it is highly recommended for the treatment of recurrent or refractory CDI. Lately, interest is growing in the therapeutic potential of FMT for other diseases, including cancers. We briefly reviewed the current researches about gut microbiota and its link to cancer, and then summarized the recent preclinical and clinical evidence to indicate the potential of FMT in cancer management as well as cancer‐treatment associated complications. We also presented the rationale of FMT for cancer management such as reconstruction of intestinal microbiota, amelioration of bile acid metabolism, and modulation of immunotherapy efficacy. This article would help to better understand this new therapeutic approach for cancer patients by targeting gut microbiota.

Gut microbes as future therapeutics in treating inflammatory and infectious diseases: Lessons from recent findings

The human gut microbiota has been the interest of extensive research in recent years and our knowledge on using the potential capacity of these microbes are growing rapidly. Microorganisms colonized throughout the gastrointestinal tract of human are coevolved through symbiotic relationship and can influence physiology, metabolism, nutrition and immune functions of an individual. The gut microbes are directly involved in conferring protection against pathogen colonization by inducing direct killing, competing with nutrients and enhancing the response of the gut-associated immune repertoire. Damage in the microbiome (dysbiosis) is linked with several life-threatening outcomes viz. inflammatory bowel disease, cancer, obesity, allergy, and auto-immune disorders. Therefore, the manipulation of human gut microbiota came out as a potential choice for therapeutic intervention of the several human diseases. Herein, we review significant studies emphasizing the influence of the gut microbiota on the regulation of host responses in combating infectious and inflammatory diseases alongside describing the promises of gut microbes as future therapeutics.

Increased Pancreatic Protease Activity in Response to Antibiotics Impairs Gut Barrier and Triggers Colitis

Background & Aims

Antibiotic (ABx) therapy is associated with increased risk for Crohn's disease but underlying mechanisms are unknown. We observed high fecal serine protease activity (PA) to be a frequent side effect of ABx therapy. The aim of the present study was to unravel whether this rise in large intestinal PA may promote colitis development via detrimental effects on the large intestinal barrier.

Methods

Transwell experiments were used to assess the impact of high PA in ABx-treated patients or vancomycin/metronidazole-treated mice on the epithelial barrier. Serine protease profiling was performed using liquid chromatography-mass spectrometry/mass spectrometry analysis. The impact of high large intestinal PA on the intestinal barrier in wild-type and interleukin (IL)10-/- mice and on colitis development in IL10-/- mice was investigated using vancomycin/metronidazole with or without oral serine protease inhibitor (AEBSF) treatment.

Results

The ABx-induced, high large intestinal PA was caused by significantly increased levels of pancreatic proteases and impaired epithelial barrier integrity. In wild-type mice, the rise in PA caused a transient increase in intestinal permeability but did not affect susceptibility to chemically induced acute colitis. In IL10-/- mice, increased PA caused a consistent impairment of the intestinal barrier associated with inflammatory activation in the large intestinal tissue. In the long term, the vancomycin/metronidazole-induced lasting increase in PA aggravated colitis development in IL10-/- mice.

Conclusions

High large intestinal PA is a frequent adverse effect of ABx therapy, which is detrimental to the large intestinal barrier and may contribute to the development of chronic intestinal inflammation in susceptible individuals.

Impact of long-term antihypertensive and antidiabetic medications on the prognosis of post-surgical colorectal cancer: the Fujian prospective investigation of cancer (FIESTA) study

Hypertension and diabetes mellitus are common comorbidities of colorectal cancer. We designed a prospective cohort study aiming to investigate the impact of long-term antihypertensive and antidiabetic medications on colorectal cancer-specific survival and recurrence among 713 post-surgical patients. All participants received radical resection for colorectal cancer during 2000-08, and they were followed up until July 2017. Colorectal cancer patients without hypertension had better survival than those with hypertension (median survival time [MST]: 190.3 months versus 99.0 months, p <0.001). The impact of antidiabetic medications on prolonging colorectal cancer survival was statistically significant, that is, patients receiving antidiabetic medications had longer survival time than untreated diabetic patients (MST: 135.8 months versus 80.2 months, p: 0.007), whereas the prognosis was greatly improved in colorectal cancer patients without diabetes mellitus (p <0.001). Medical treatment for hypertension and diabetes mellitus was associated with 28% (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.47-1.10; p: 0.131) and 57% (HR: 0.43; 95% CI: 0.22-0.82; p: 0.010) reduced risk of dying from colorectal cancer relative to those without medications, respectively. Our data indicate that long-term antidiabetic medications can significantly prolong the survival and improve the prognosis of post-surgical colorectal cancer.

Antibiotic-mediated bacteriome depletion in ApcMin/+ mice is associated with reduction in mucus-producing goblet cells and increased colorectal cancer progression

Recent epidemiological evidence suggests that exposure to antibiotics in early‐to‐middle adulthood is associated with an increased risk of colorectal adenoma. However, mechanistic studies in established preclinical cancer to examine these claims are extremely limited. Therefore, we investigated the effect of long‐term exposure of an antibiotic cocktail composed of Vancomycin, Neomycin, and Streptomycin, on tumor development and progression in the Apc^Min/+ mouse, an established genetic model for familial adenomatous polyposis. Clinical pathologies related to tumor development as well as intestinal and colon tissue histopathology were studied at ages 8, 12, and 16 weeks of age, which correspond to the approximate ages of development of neoplasia, gut inflammation with polyposis, and cancer progression, respectively, in this animal model. We show that the antibiotics significantly increase the severity of clinical symptoms, including effects on intestinal histology and goblet cell numbers. In addition, they promote small intestinal polyposis. Finally, metagenomic analysis of fecal samples demonstrated that antibiotic exposure is associated with a significant but nonuniform depletion of the animal's natural gut flora. Overall, these findings support the premise that long‐term antibiotic exposure mediates the selected depletion of gut microbial communities and the concomitant thinning of the protective mucus layer, resulting in an increase in tumor development.

Long-term use of antibiotics and risk of colorectal adenoma

OBJECTIVE

Recent evidence suggests that antibiotic use, which alters the gut microbiome, is associated with an increased risk of colorectal cancer. However, the association between antibiotic use and risk of colorectal adenoma, the precursor for the majority of colorectal cancers, has not been investigated.

DESIGN

We prospectively evaluated the association between antibiotic use at age 20-39 and 40-59 (assessed in 2004) and recent antibiotic use (assessed in 2008) with risk of subsequent colorectal adenoma among 16 642 women aged ≥60 enrolled in the Nurses' Health Study who underwent at least one colonoscopy through 2010. We used multivariate logistic regression to calculate ORs and 95% CIs.

RESULTS

We documented 1195 cases of adenoma. Increasing duration of antibiotic use at age 20-39 (ptrend=0.002) and 40-59 (ptrend=0.001) was significantly associated with an increased risk of colorectal adenoma. Compared with non-users, women who used antibiotics for ≥2 months between age 20 and 39 had a multivariable OR of 1.36 (95% CI 1.03 to 1.79). Women who used ≥2 months of antibiotics between age 40 and 59 had a multivariable OR of 1.69 (95% CI 1.24 to 2.31). The associations were similar for low-risk versus high-risk adenomas (size ≥1 cm, or with tubulovillous/villous histology, or ≥3 detected lesions), but appeared modestly stronger for proximal compared with distal adenomas. In contrast, recent antibiotic use within the past four years was not associated with risk of adenoma (ptrend=0.44).

CONCLUSIONS

Long-term antibiotic use in early-to-middle adulthood was associated with increased risk of colorectal adenoma.

Gut bacteria are required for the benefits of black raspberries in Apc Min/+ mice

BACKGROUND

The gut microbiota plays a pivotal role in the development of inflammatory bowel disease and colorectal cancer.

OBJECTIVE

To determine whether the gut microbiota is required for the chemoprotective effects of black raspberries (BRBs) in Apc ^Min/+ mice.

METHODS

Apc ^Min/+ mice were given (a) a control diet for 8 weeks, or (b) the control diet for 4 weeks and then a 5% BRB diet for additional 4 weeks, or (c) the control diet and antibiotics for 4 weeks followed by the 5% BRB diet and antibiotics for the next 4 weeks. At the end of the study, all the mice were euthanized, and colonic and intestinal polyps were counted. mRNA expression levels of TLR4, NF-κB1, and COX2 were determined in colon and small intestine of these Apc ^Min/+ mice by quantitative real-time PCR.

RESULTS

5% BRBs significantly suppressed intestinal and colonic polyp development in the Apc ^Min/+ mice, whereas antibiotics significantly abolished BRBs' chemoprotective effects. BRBs decreased mRNA levels of TLR4, NF-κB1, and COX2 in colon, whereas significantly enhanced mRNA levels of TLR4 and NF-κB1 were observed in small intestine of BRB-treated Apc ^Min/+ mice fed antibiotics.

CONCLUSIONS

The gut microbiota is required for BRBs' chemoprotection against polyp development in Apc ^Min/+ mice.

Resistance Mechanisms to Immune-Checkpoint Blockade in Cancer: Tumor-Intrinsic and -Extrinsic Factors

Inhibition of immune regulatory checkpoints, such as CTLA-4 and the PD-1-PD-L1 axis, is at the forefront of immunotherapy for cancers of various histological types. However, such immunotherapies fail to control neoplasia in a significant proportion of patients. Here, we review how a range of cancer-cell-autonomous cues, tumor-microenvironmental factors, and host-related influences might account for the heterogeneous responses and failures often encountered during therapies using immune-checkpoint blockade. Furthermore, we describe the emerging evidence of how the strong interrelationship between the immune system and the host microbiota can determine responses to cancer therapies, and we introduce a concept by which prior or concomitant modulation of the gut microbiome could optimize therapeutic outcomes upon immune-checkpoint blockade.

[Gut microbiota and efficacy of cancer therapies]

The gut microbiota is known to affect digestion, protection against pathogens infection, immune system maturation and enteric nervous system development, but others links have also been established with diabetes, obesity, autism and cancer. Lately, bacterial species from the gut have been involved in tumor immunosurveillance. Natural or mediated by treatment such as chemotherapy or immunotherapy, anti-tumoral immune responses seem to rely on gut microbiota. The bacteria involved and their mechanisms of action are different according to the treatment of interest. Nevertheless, modulation of gut microbiota represents a great potential with the development of onco-micro-biotics to optimize the response to cancer therapies.

The Host Microbiome Regulates and Maintains Human Health: A Primer and Perspective for Non-Microbiologists

Humans consider themselves discrete autonomous organisms, but recent research is rapidly strengthening the appreciation that associated microorganisms make essential contributions to human health and well being. Each person is inhabited and also surrounded by his/her own signature microbial cloud. A low diversity of microorganisms is associated with a plethora of diseases, including allergy, diabetes, obesity, arthritis, inflammatory bowel diseases, and even neuropsychiatric disorders. Thus, an interaction of microorganisms with the host immune system is required for a healthy body. Exposure to microorganisms from the moment we are born and appropriate microbiome assembly during childhood are essential for establishing an active immune system necessary to prevent disease later in life. Exposure to microorganisms educates the immune system, induces adaptive immunity, and initiates memory B and T cells that are essential to combat various pathogens. The correct microbial-based education of immune cells may be critical in preventing the development of autoimmune diseases and cancer. This review provides a broad overview of the importance of the host microbiome and accumulating knowledge of how it regulates and maintains a healthy human system. Cancer Res; 77(8); 1783-812. ©2017 AACR.

Long-term use of antibiotics and risk of colorectal adenoma

OBJECTIVE

Recent evidence suggests that antibiotic use, which alters the gut microbiome, is associated with an increased risk of colorectal cancer. However, the association between antibiotic use and risk of colorectal adenoma, the precursor for the majority of colorectal cancers, has not been investigated.

DESIGN

We prospectively evaluated the association between antibiotic use at age 20-39 and 40-59 (assessed in 2004) and recent antibiotic use (assessed in 2008) with risk of subsequent colorectal adenoma among 16 642 women aged ≥60 enrolled in the Nurses' Health Study who underwent at least one colonoscopy through 2010. We used multivariate logistic regression to calculate ORs and 95% CIs.

RESULTS

We documented 1195 cases of adenoma. Increasing duration of antibiotic use at age 20-39 (p_trend=0.002) and 40-59 (p_trend=0.001) was significantly associated with an increased risk of colorectal adenoma. Compared with non-users, women who used antibiotics for ≥2 months between age 20 and 39 had a multivariable OR of 1.36 (95% CI 1.03 to 1.79). Women who used ≥2 months of antibiotics between age 40 and 59 had a multivariable OR of 1.69 (95% CI 1.24 to 2.31). The associations were similar for low-risk versus high-risk adenomas (size ≥1 cm, or with tubulovillous/villous histology, or ≥3 detected lesions), but appeared modestly stronger for proximal compared with distal adenomas. In contrast, recent antibiotic use within the past four years was not associated with risk of adenoma (p_trend=0.44).

CONCLUSIONS

Long-term antibiotic use in early-to-middle adulthood was associated with increased risk of colorectal adenoma.

Antidepressants and colorectal cancer: A population-based nested case-control study

BACKGROUND

Experimental evidence indicates that serotonin is associated with both proliferative and pro-carcinogenic effects on colorectal tumors. The present study aims to investigate the associations between antidepressant use and colorectal cancer in an epidemiological sample.

METHODS

We conducted a population-based case-control study utilizing Taiwan's National Health Insurance Research Database (NHIRD). We identified 49,342 cases with colorectal cancer and 240,985 controls between 1997 and 2008. We conducted conditional logistic regression analyses to assess the association between antidepressant use and colorectal cancer risk. Sensitivity analyses were conducted to assess whether genotoxic antidepressants (i.e. antidepressants which may exert procarcinogenic effects) would increase risk for colorectal cancer.

RESULTS

Selective serotonin reuptake inhibitors (adjusted OR=1.00, 95% CI=0.94-1.06), tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and serotonin antagonist and reuptake inhibitors were not associated with increased incidence of colorectal cancer. Monoamine oxidase inhibitors were, however, associated with an increased incidence of colorectal cancer (adjusted OR=1.22, 95% CI=1.06-1.41). Higher cumulative dose of mirtazapine was associated with a decreased incidence of colorectal cancer (adjusted OR=0.39, 95% CI=0.17-0.90). A small sample size of individuals who received mirtazapine, however, precludes definitive conclusions regarding protective effects with mirtazapine.

LIMITATIONS

We could not discern the effects of obesity and other risk factors for colorectal cancer from the NHIRD.

CONCLUSIONS

Contemporary first-line antidepressants (i.e. SSRI, SNRI), as well as older agents (i.e. TCA), are not associated with increased incidence of colorectal cancer.