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

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 microbial landscape of colorectal cancer

Colorectal cancer (CRC) is a substantial source of global morbidity and mortality in dire need of improved prevention and treatment strategies. As our understanding of CRC grows, it is becoming increasingly evident that the gut microbiota, consisting of trillions of microorganisms in direct interface with the colon, plays a substantial role in CRC development and progression. Understanding the roles that individual microorganisms and complex microbial communities play in CRC pathogenesis, along with their attendant mechanisms, will help yield novel preventive and therapeutic interventions for CRC. In this Review, we discuss recent evidence concerning global perturbations of the gut microbiota in CRC, associations of specific microorganisms with CRC, the underlying mechanisms by which microorganisms potentially drive CRC development and the roles of complex microbial communities in CRC pathogenesis. While our understanding of the relationship between the microbiota and CRC has improved in recent years, our findings highlight substantial gaps in current research that need to be filled before this knowledge can be used to the benefit of patients.

Fecal Carriage of Colibactin-Encoding Escherichia coli Associated With Colorectal Cancer Among a Student Populace

Fecal carriage of the colibactin (clb) gene in Escherichia coli is described as a source that could promote carcinogenesis, progressing to colorectal cancer. The present study investigated the demographic, dietary, and antibiotic consumption variables as correlates for fecal carriage of clb+/E coli among the student populace. In a randomized cross-sectional survey, E coli (N = 136) from the fecal samples of eligible students were characterized and evaluated for antibiotic resistance, β-lactamase (blm), biofilm, virulence factor production, and strain tryptophan reverse mutagenic activity. The encoded clb+/E coli were analyzed for correlates with principal component analysis. Of all the E coli strains, a low rate of 2 clb+/E coli (1.5%) and higher rates of biofilm (13.2%) and blm producers (11.8%) were recorded among the mutant strains as compared with the nonmutant types. All the clb+/E coli showed complete resistance to amoxicillin, Augmentin (amoxicillin and clavulanate), gentamicin, and trimethoprim/sulfamethoxazole. The fecal clb-encoded E coli (1.5%) were not associated with demographic status, fiber-based food (odds ratio [OR], 1.03; 95% CI, 56.74-138.7; P = .213), alcohol (OR, 1.27; 95% CI, 61.74-147.1; P = .221), antibiotic consumptions (OR, 1.11; 95% CI, 61.29-145.3; P = .222), and handwashing (OR, 1.17; 95% CI, 60.19-145.5; P = .216). The hierarchical cluster of blm+/E coli revealed high-level resistance with a multiantibiotic resistance index ≥0.2 (P < .05). Only 12% of all strains were tryptophan mutant/blm+, and 1.5% of clb+/ECblm+ were observed in fecal samples with a 452-base pair size. Trimethoprim/sulfamethoxazole and biofilm production positively regressed with clb expression (P > .05). Principal component analysis score plot indicated an association of clb+/ECblm+ with dietary pattern, alcohol, blm, and hemolysin production. The combined activity of blm and biofilm production in the gut microbiota could promote clb+/E coli colonization, facilitating genotoxin production and possible colorectal cancer induction.

The gut microbiota in adults with cystic fibrosis compared to colorectal cancer

BACKGROUND

Gut dysbiosis is implicated in colorectal cancer (CRC) pathogenesis. Cystic fibrosis (CF) is associated with both gut dysbiosis and increased CRC risk. We therefore compared the faecal microbiota from individuals with CF to CRC and screening samples. We also assessed changes in CRC-associated taxa before and after triple CF transmembrane conductance regulator (CFTR) modulator therapy.

METHODS

Bacterial DNA amplification comprising V4 16S rRNA analysis was conducted on 84 baseline and 53 matched follow-up stool samples from adults with CF. These data were compared to an existing cohort of 430 CRC and 491 control gFOBT samples from the NHS Bowel Cancer Screening Programme. Data were also compared to 26 previously identified CRC-associated taxa from a published meta-analysis.

RESULTS

Faecal CF samples had a lower alpha diversity and clustered distinctly from both CRC and control samples, with no clear clinical variables explaining the variation. Compared to controls, CF samples had an increased relative abundance in 6 of the 20 enriched CRC-associated taxa and depletion of 2 of the 6 taxa which have been reported as reduced in CRC. Commencing triple modulator therapy had subtle influence on the relative abundance of CRC-associated microbiota (n = 23 paired CF samples).

CONCLUSIONS

CF stool samples were clearly dysbiotic, clustering distinctly from both CRC and control samples. Several bacterial shifts in CF samples resembled those observed in CRC. Studies assessing the impact of dietary or other interventions and the longer-term use of CFTR modulators on reducing this potentially pro-oncogenic milieu are needed.

The role of the gut microbiome in gastrointestinal cancers

The gut microbiota present in the human digestive system is incredibly varied and is home to trillions of microorganisms. The gut microbiome is shaped at birth, while numerous genetic, dietary, and environmental variables primarily influence the microbiome composition. The importance of gut microbiota on host health is becoming more widely acknowledged. Digestion, intestinal permeability, and immunological and metabolism responses can all be affected by changes in the composition and function of the gut microbiota. There is mounting evidence that the microbial population's complex traits are important biomarkers and indicators of patient outcomes in cancer and its therapies. Numerous studies have demonstrated that changed commensal gut microorganisms contribute to the development and spread of cancer through various routes. Despite the ongoing controversy surrounding the gut microbiome and gastrointestinal cancer, accumulating evidence points to a potentially far more intricate connection than a simple cause-and-effect relationship. SIMPLE SUMMARY: Due to their high frequency and fatality rate, gastrointestinal cancers are regarded as a severe public health issue with complex medical and economic burdens. The gut microbiota may directly or indirectly interact with existing therapies like immunotherapy and chemotherapy, affecting how well a treatment works. The gut microbiome influences the immune response's activity, function, and development. Generally, certain gut bacteria impact the antitumor actions during cancer by creating particular metabolites or triggering T-cell responses. Yet, certain bacterial species have been found to promote cellular proliferation and metastasis in cancer, and comprehending these interactions in the context of cancer may help identify possible treatment targets. Notwithstanding the improvements in the field, additional research is still required to comprehend the underlying processes, examine the effects on existing therapies, and pinpoint certain bacteria and immune cells that can cause this interaction.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

Pharmaceutical Agents as Potential Drivers in the Development of Early-Onset Colorectal Cancer: Case-Control Study

BACKGROUND

The incidence of early-onset colorectal cancer (EOCRC) rose abruptly in the mid 1990s, is continuing to increase, and has now been noted in many countries. By 2030, 25% of American patients diagnosed with rectal cancer will be 49 years or younger. The large majority of EOCRC cases are not found in patients with germline cancer susceptibility mutations (eg, Lynch syndrome) or inflammatory bowel disease. Thus, environmental or lifestyle factors are suspected drivers. Obesity, sedentary lifestyle, diabetes mellitus, smoking, alcohol, or antibiotics affecting the gut microbiome have been proposed. However, these factors, which have been present since the 1950s, have not yet been conclusively linked to the abrupt increase in EOCRC. The sharp increase suggests the introduction of a new risk factor for young people. We hypothesized that the driver may be an off-target effect of a pharmaceutical agent (ie, one requiring regulatory approval before its use in the general population or an off-label use of a previously approved agent) in a genetically susceptible subgroup of young adults. If a pharmaceutical agent is an EOCRC driving factor, regulatory risk mitigation strategies could be used.

OBJECTIVE

We aimed to evaluate the possibility that pharmaceutical agents serve as risk factors for EOCRC.

METHODS

We conducted a case-control study. Data including demographics, comorbidities, and complete medication dispensing history were obtained from the electronic medical records database of Maccabi Healthcare Services, a state-mandated health provider covering 26% of the Israeli population. The participants included 941 patients with EOCRC (≤50 years of age) diagnosed during 2001-2019 who were density matched at a ratio of 1:10 with 9410 control patients. Patients with inflammatory bowel disease and those with a known inherited cancer susceptibility syndrome were excluded. An advanced machine learning algorithm based on gradient boosted decision trees coupled with Bayesian model optimization and repeated data sampling was used to sort through the very high-dimensional drug dispensing data to identify specific medication groups that were consistently linked with EOCRC while allowing for synergistic or antagonistic interactions between medications. Odds ratios for the identified medication classes were obtained from a conditional logistic regression model.

RESULTS

Out of more than 800 medication classes, we identified several classes that were consistently associated with EOCRC risk across independently trained models. Interactions between medication groups did not seem to substantially affect the risk. In our analysis, drug groups that were consistently positively associated with EOCRC included beta blockers and valerian (Valeriana officinalis). Antibiotics were not consistently associated with EOCRC risk.

CONCLUSIONS

Our analysis suggests that the development of EOCRC may be correlated with prior use of specific medications. Additional analyses should be used to validate the results. The mechanism of action inducing EOCRC by candidate pharmaceutical agents will then need to be determined.

The Role of the Gut Microbiome in Cancer: A Review, With Special Focus on Colorectal Neoplasia and Clostridioides difficile

The gut microbiome has coevolved with humans to aid in physiologic functions and prevent disease. An increasing prevalence of gut dysbiosis in modern society exists and has strong linkages to multiple disease processes common in the developed world. Mechanisms for microbiome-human interactions that impact host homeostasis include bacterial metabolite/toxin production, biofilm formation with mucous layer infiltration, and host immune system modulation. Most of this crosstalk occurs at the epithelial layer of the gut, and as such the role of these interactions in the induction of colorectal cancer-a highly prevalent disease globally and one undergoing significant epidemiologic shifts-is under increasing scrutiny. Although multiple individual gut bacteria have been hypothesized as possible driver organisms in the oncogenic process, no bacterium has been definitively identified as a causal agent of colorectal cancer, suggesting that host lifestyle factors, microbiome community interactions, and the mucosal and/or systemic immune response may play a critical role in the process. Recent evidence has emerged implicating the ubiquitous human pathogen Clostridioides difficile as a possible promoter of colorectal cancer through chronic toxin-mediated cellular changes. Although much remains to be defined regarding the natural history of infections caused by this pathogen and its potential for oncogenesis, it provides a strong model for the role of both individual bacteria and of the gut microbial community as a whole in the development of colorectal cancer.

In-utero exposure to antibiotics and risk of colorectal cancer in a prospective cohort of 18 000 adult offspring

BACKGROUND

Incidence rates of colorectal cancer (CRC) are increasing among younger adults and in mid-life, implicating exposures in early life as risk factors. We examined the association between in-utero exposure to antibiotics and risk of CRC in adult offspring.

METHODS

The Child Health and Development Studies is a prospective cohort of women receiving prenatal care between 1959 and 1966 in Oakland, California, with deliveries through June 1967. Diagnosed conditions and all prescribed medications were abstracted from mothers' medical records beginning 6 months prior to pregnancy through delivery. We identified mothers who received antibiotics in pregnancy, including penicillins, tetracyclines, short-acting sulfonamides and long-acting sulfonamides. Diagnoses of CRC in adult (age ≥18 years) offspring were ascertained through 2021 by linkage with the California Cancer Registry. Cox proportional models were used to estimate adjusted hazard ratios (aHR), with follow-up accrued from birth through cancer diagnosis, death or last contact.

RESULTS

Of 18 751 liveborn offspring, about 15% (n = 2635) were exposed in utero to antibiotics: 5.4% (n = 1016) to tetracyclines, 4.9% (n = 918) to penicillins, 4.2% (n = 785) to short-acting sulfonamides and 1.5% (n = 273) to long-acting sulfonamides. Compared with offspring not exposed, associations between in-utero exposure and CRC in adult offspring were: aHR 1.03 (95% CI 0.32, 3.31) for tetracyclines; aHR 1.12 (95% CI 0.35, 3.58) for penicillins; aHR 0.83 (95% CI 0.20, 3.42) for short-acting sulfonamides; and aHR 4.40 (95% CI 1.63, 11.88) for long-acting sulfonamides.

CONCLUSION

Our findings support an association between in-utero exposure to long-acting sulfonamides and CRC in adulthood.

Prediagnostic Prescription Antibiotics Use and Survival in Patients with Colorectal Cancer: A Swedish National Register-Based Study

BACKGROUND

Antibiotics use is associated with higher colorectal cancer risk, but little is known regarding any potential effects on survival.

METHODS

We conducted a nationwide cohort study, using complete-population data from Swedish national registers between 2005 and 2020, to investigate prediagnostic prescription antibiotics use in relation to survival in colorectal cancer patients.

RESULTS

We identified 36,061 stage I-III and 11,242 stage IV colorectal cancer cases diagnosed between 2010 and 2019. For stage I-III, any antibiotics use (binary yes/no variable) was not associated with overall or cancer-specific survival. Compared with no use, moderate antibiotics use (total 11-60 days) was associated with slightly better cancer-specific survival [adjusted HR (aHR) = 0.93; 95% confidence interval (CI), 0.86-0.99)], whereas very high use (>180 days) was associated with worse survival [overall survival (OS) aHR = 1.42; 95% CI, 1.26-1.60, cancer-specific survival aHR = 1.31; 95% CI, 1.10-1.55]. In analyses by different antibiotic types, although not statistically significant, worse survival outcomes were generally observed across several antibiotics, particularly macrolides and/or lincosamides. In stage IV colorectal cancer, inverse relationships between antibiotics use and survival were noted.

CONCLUSIONS

Overall, our findings do not support any substantial detrimental effects of prediagnostic prescription antibiotics use on cancer-specific survival after colorectal cancer diagnosis, with the possible exception of very high use in stage I-III colorectal cancer. Further investigation is warranted to confirm and understand these results.

IMPACT

Although the study findings require confirmation, physicians probably do not need to factor in prediagnostic prescription antibiotics use in prognosticating patients with colorectal cancer.

Antibiotic Exposure is Associated With a Risk of Esophageal Adenocarcinoma

BACKGROUND & AIMS

Antibiotic exposure leads to changes in the gut microbiota. Our objective was to evaluate the association between antibiotic exposure and esophageal adenocarcinoma (EAC) risk.

METHODS

We performed a nested case-control study using data from the Veterans Health Administration from 2004 through 2020. The case group consisted of patients who received an incident diagnosis of EAC. For each case, up to 20 matched controls were selected using incidence density sampling. Our primary exposure of interest was any oral or intravenous antibiotic use. Our secondary exposures included cumulative number of days of exposure and classification of antibiotics by various subgroups. Conditional logistic regression was used to estimate the crude and adjusted odds ratios (aORs) for the risk of EAC associated with antibiotic exposure.

RESULTS

The case-control analysis included 8226 EAC cases and 140,670 matched controls. Exposure to any antibiotic was associated with an aOR for EAC of 1.74 (95% confidence interval [CI], 1.65-1.83) vs no antibiotic exposure. Compared with no antibiotic exposure, the aOR for EAC was 1.63 (95% CI, 1.52-1.74; P < .001) for cumulative exposure to any antibiotic for 1 to 15 days; 1.77 (95% CI, 1.65-1.89; P < 0 .001) for 16 to 47 days; and 1.87 (95% CI, 1.75-2.01; P < .001) for ≥48 days, respectively (P for trend < .001).

CONCLUSION

Exposure to any antibiotic is associated with an increased risk of EAC, and this risk increases as the cumulative days of exposure increase. This novel finding is hypothesis-generating for potential mechanisms that may play a role in the development or progression of EAC.

Survival Outcome in Early-Onset Metastatic Colorectal Cancer: A Multicenter-Matched Pair Analysis

INTRODUCTION

Survival of patients suffering from metastatic colorectal cancer (mCRC) has increased over the last decades. These benefits appear to be restricted to patients aged 50 and above. However, among the population aged <50, colorectal cancer incidence and mortality rates are significantly rising. The clinical benefit of treatment in this population still is a matter of debate. We aim to compare the clinical outcome between patients aged 50 and younger.

METHODS

In this retrospective, observational study, we analyzed data from 1,077 patients treated for mCRC at three cancer centers in Austria from January 2005 to December 2019. Patients were divided into two groups based on age at diagnosis: <50 years (eo-CRC) and >50 years (regular-onset CRC, ro-CRC). Propensity score matching was used to control for potential biases, and survival outcomes were compared between the two groups.

RESULTS

The differences in tumor characteristics between eo-CRC and ro-CRC in the overall population were primarily related to tumor sidedness and disease-free survival following intended curative resection. Our data show that eo-CRC patients underwent metastases resection more often and received significantly more lines of treatment in the palliative setting. Overall survival was superior in eo-CRC compared to ro-CRC, even after adjusting for sidedness, timing of metastases, sex, number of treatment lines, and resection of metastases by propensity scoring.

CONCLUSION

Our study suggests that younger patients benefit at least to the same magnitude or even more from mCRC-treatment than patients aged 50 or above.

Gut microbiota interactions with antitumor immunity in colorectal cancer: From understanding to application

Colorectal cancer (CRC) is one of highly prevalent cancer. Immunotherapy with immune checkpoint inhibitors (ICIs) has dramatically changed the landscape of treatment for many advanced cancers, but CRC still exhibits suboptimal response to immunotherapy. The gut microbiota can affect both anti-tumor and pro-tumor immune responses, and further modulate the efficacy of cancer immunotherapy, particularly in the context of therapy with ICIs. Therefore, a deeper understanding of how the gut microbiota modulates immune responses is crucial to improve the outcomes of CRC patients receiving immunotherapy and to overcome resistance in nonresponders. The present review aims to describe the relationship between the gut microbiota, CRC, and antitumor immune responses, with a particular focus on key studies and recent findings on the effect of the gut microbiota on the antitumor immune activity. We also discuss the potential mechanisms by which the gut microbiota influences host antitumor immune responses as well as the prospective role of intestinal flora in CRC treatment. Furthermore, the therapeutic potential and limitations of different modulation strategies for the gut microbiota are also discussed. These insights may facilitate to better comprehend the interplay between the gut microbiota and the antitumor immune responses of CRC patients and provide new research pathways to enhance immunotherapy efficacy and expand the patient population that could be benefited by immunotherapy.

Risk Factors for Early-onset Sporadic Colorectal Cancer in Male Veterans

Identifying risk factors for early-onset colorectal cancer (EOCRC) could help reverse its rising incidence through risk factor reduction and/or early screening. We sought to identify EOCRC risk factors that could be used for decisions about early screening. Using electronic databases and medical record review, we compared male veterans ages 35 to 49 years diagnosed with sporadic EOCRC (2008-2015) matched 1:4 to clinic and colonoscopy controls without colorectal cancer, excluding those with established inflammatory bowel disease, high-risk polyposis, and nonpolyposis syndromes, prior bowel resection, and high-risk family history. We ascertained sociodemographic and lifestyle factors, family and personal medical history, physical measures, vital signs, medications, and laboratory values 6 to 18 months prior to case diagnosis. In the derivation cohort (75% of the total sample), univariate and multivariate logistic regression models were used to derive a full model and a more parsimonious model. Both models were tested using a validation cohort. Among 600 cases of sporadic EOCRC [mean (SD) age 45.2 (3.5) years; 66% White], 1,200 primary care clinic controls [43.4 (4.2) years; 68% White], and 1,200 colonoscopy controls [44.7 (3.8) years; 63% White], independent risk factors included age, cohabitation and employment status, body mass index (BMI), comorbidity, colorectal cancer, or other visceral cancer in a first- or second-degree relative (FDR or SDR), alcohol use, exercise, hyperlipidemia, use of statins, NSAIDs, and multivitamins. Validation c-statistics were 0.75-0.76 for the full model and 0.74-0.75 for the parsimonious model, respectively. These independent risk factors for EOCRC may identify veterans for whom colorectal cancer screening prior to age 45 or 50 years should be considered.

PREVENTION RELEVANCE

Screening 45- to 49-year-olds for colorectal cancer is relatively new with uncertain uptake thus far. Furthermore, half of EOCRC occurs in persons < 45 years old. Using risk factors may help 45- to 49-year-olds accept screening and may identify younger persons for whom earlier screening should be considered. See related Spotlight, p. 479.

Field Synopsis of Environmental and Genetic Risk Factors of Sporadic Early-Onset Colorectal Cancer and Advanced Adenoma

BACKGROUND

To systematically appraise and synthesize available epidemiologic evidence on the associations of environmental and genetic factors with the risk of sporadic early-onset colorectal cancer (EOCRC) and early-onset advanced colorectal adenoma (EOCRA).

METHODS

Multiple databases were comprehensively searched to identify eligible observational studies. Genotype data from UK Biobank were incorporated to examine their associations with EOCRC in a nested case-control design. Meta-analyses of environmental risk factors were performed, and the strength of evidence was graded based on predefined criteria. Meta-analyses of genetic associations were conducted using the allelic, recessive, and dominant models, respectively.

RESULTS

A total of 61 studies were included, reporting 120 environmental factors and 62 genetic variants. We found 12 risk factors (current overweight, overweight in adolescence, high waist circumference, smoking, alcohol, sugary beverages intake, sedentary behavior, red meat intake, family history of colorectal cancer, hypertension, hyperlipidemia, and metabolic syndrome) and three protective factors (vitamin D, folate, and calcium intake) for EOCRC or EOCRA. No significant associations between the examined genetic variants and EOCRC risk were observed.

CONCLUSIONS

Recent data indicate that the changing patterns of traditional colorectal cancer risk factors may explain the rising incidence of EOCRC. However, research on novel risk factors for EOCRC is limited; therefore, we cannot rule out the possibility of EOCRC having different risk factors than late-onset colorectal cancer (LOCRC).

IMPACT

The potential for the identified risk factors to enhance the identification of at-risk groups for personalized EOCRC screening and prevention and for the prediction of EOCRC risk should be comprehensively addressed by future studies.

Impact of Colorectal Cancer Sidedness and Location on Therapy and Clinical Outcomes: Role of Blood-Based Biopsy for Personalized Treatment

Colorectal cancer is one of the most common malignant diseases in the United States and worldwide, and it remains among the top three causes of cancer-related death. A new understanding of molecular characteristics has changed the profile of colorectal cancer and its treatment. Even controlling for known mutational differences, tumor side of origin has emerged as an independent prognostic factor, and one that impacts response to therapy. Left- and right-sided colon cancers differ in a number of key ways, including histology, mutational profile, carcinogenesis pathways, and microbiomes. Moreover, the frequency of certain molecular features gradually changes from the ascending colon to rectum. These, as well as features yet to be identified, are likely responsible for the ongoing role of tumor sidedness and colorectal subsites in treatment response and prognosis. Along with tumor molecular profiling, blood-based biopsy enables the identification of targetable mutations and predictive biomarkers of treatment response. With the application of known tumor characteristics including sidedness and subsites as well as the utilization of blood-based biopsy, along with the development of biomarkers and targeted therapies, the field of colorectal cancer continues to evolve towards the personalized management of a heterogeneous cancer.

A dose-dependent increase in the risk of inflammatory bowel disease after exposure to broad-spectrum antibiotics: A national population study in Korea

BACKGROUND

The association between antibiotic use and risk of inflammatory bowel disease (IBD), particularly among adults, remains unclear. Furthermore, there is a scarcity of data among non-Western countries.

AIMS

To investigate the association and dose-response relationships between antibiotic use and subsequent IBD risk across all ages METHODS: This population-based case-control analysis used data from the Korean National Health Insurance Service database (2004-2018). We compared 68,633 patients with new-onset IBD to matched controls (n = 343,165) using multivariable conditional logistic regression analysis. We also examined the dose-response relationship using non-linear regression analysis, and separately analysed childhood-onset IBD (aged ≤14 years) risk following early-life antibiotic exposure.

RESULTS

The mean age at diagnosis was 45.2 ± 16.8 years. Antibiotic prescriptions between 2 and 5 years before diagnosis significantly increased the odds of developing IBD (adjusted odds ratio [OR], 1.24; 95% confidence interval [CI]: 1.21-1.27). Additionally, sensitivity analysis revealed an elevated risk up to 9 years before diagnosis. Broad-spectrum antibiotics increased IBD risk, independent of gastroenteritis. A distinct dose-response relationship was observed irrespective of the IBD subtype and study population (all p < 0.001). Furthermore, antibiotic exposure within the first year of life was linked with the risk of childhood-onset IBD (OR, 1.51; 95% CI: 1.25-1.82).

CONCLUSIONS

Broad-spectrum antibiotics dose-dependently increased the risk for IBD in the Korean population. Our findings provide a fundamental epidemiological basis for identifying antibiotic use as a significant risk factor for IBD across different environmental backgrounds.

Early-Onset Colorectal Cancer: Current Insights

Over the past decade, the incidence of colorectal cancer has increased in individuals under the age of 50 years. Meanwhile, the incidence has gradually decreased in the older population. As described herein, we reviewed the available literature to summarize the current landscape of early-onset colorectal cancer, including risk factors, clinicopathological presentation, genetic makeup of patients, and management. Currently, early-onset colorectal cancer is treated similarly as late-onset colorectal cancer, yet the available literature shows that early-onset colorectal cancer is more aggressive and different, and this remains a significant unmet need. A detailed understanding of early-onset colorectal cancer is needed to identify risk factors for the increased incidence and tailor treatments accordingly.

Comparison of the short- and long-term prognosis of early-onset colorectal cancer compared with later-onset colorectal cancer: A systematic review and meta-analysis

Background and Aims

The annual incidence of early-onset colorectal cancer (EOCRC) is increasing at an alarming rate. The prognosis of EOCRC remains controversial, and whether the early onset is a risk factor for colorectal cancer remains unclear.

Methods

We searched four electronic bibliographic databases from database inception to April 25, 2022 for studies that included both early- and later-onset patients and performed a prognostic analysis. Random-effects models were used to summarize the prognostic information extracted by the investigators, including overall survival (OS), cancer-special survival (CSS), and disease-free survival (DFS). Network meta-analysis (NMA) was used to compare patients' long-term prognoses in different age subgroups.

Results

After 694 reports were screened, 13 studies were included in the final analysis, with a total of 448,781 CRC cases. In the meta-analysis of the 5-year OS, EOCRC had a better prognosis compared to LOCRC (hazard ratio [HR] 0.87, 95% confidence interval [CI], 0.74-0.99; relative risk [RR] 0.83, 95% CI, 0.78-0.89). No difference in prognosis was found between the two groups in terms of 5-year CSS (RR 0.99, 95% CI, 0.93-1.05), 5-year DFS (RR 0.90, 95% CI, 0.74-1.09), and short-term OS. In the NMA, patients aged <30 years had the worst outcome (surface under the cumulative ranking curve [SUCRA], 15.8%) in 5-year OS; consistent results were observed in the analysis of 5-year CSS (<30 years, SUCRA 4.5%), but the difference was not statistically significant.

Conclusion

Although patients with early-onset CRC had better OS than those with later-onset CRC, there was no difference in the CSS. Meanwhile, the trend for survival was worse in younger patients, especially in those ages 18-29 years. Thus, more attention should be paid to early diagnosis and treatment of EOCRC.

Systematic Review and Meta‐Analysis Registration

The systematic review and Meta-analysis protocol was registered with PROSPERO (registration number CRD42022334697).

Novel insights at the crossroads of antibiotic use and cancer risk

The continuous use of antibiotics is associated with the spread of antimicrobial resistances and the not yet clear link to cancer development. Many conventional antibiotics have already shown different effects on a variety of cancer types raising questions for their rational use in cancer. However, discrepancy in the observed trend for some antibiotics reducing cancer development and being associated with higher risk of cancer underscores the lack of understanding the complex link between antibiotics and cancer. Here, we briefly summarize the possible antibiotic-mediated effects on cancer and conclude that those effects can be direct via i) specific targeting of tumor/cancer, ii) antimicrobial activity and iii) immunomodulatory activity whereby iv) indirectly caused effects primarily affect immune equilibrium between bacteria, cancer and immune cells. Furthermore, we also conclude that there is a great need for bulk profiling, comprehensive screening programs in all countries and in-depth studies to understand the risks and benefits of antibiotic use.

Young-onset colorectal cancer

In the past decades the incidence of colorectal cancer (CRC) in people under the age of 50 years has increased, which is referred to as early-onset CRC or young-onset CRC (YO-CRC). YO-CRC is expected to account for 11% of colon cancers and 23% of rectal cancers by 2030. This trend is observed in different parts of the world and in both men and women. In 20% of patients with YO-CRC, a hereditary cancer syndrome is found as the underlying cause; however, in the majority of patients no genetic predisposition is present. Beginning in the 1950s, major changes in lifestyle such as antibiotic use, low physical activity and obesity have affected the gut microbiome and may be an important factor in YO-CRC development. Owing to a lack of screening, patients with YO-CRC are often diagnosed with advanced-stage disease. Long-term treatment-related complications should be taken into account in these younger patients, making the more traditional sequential approaches of drug therapy not always the most appropriate option. To better understand the underlying mechanism and define relationships between environmental factors and YO-CRC development, long-term prospective studies are needed with lifestyle data collected from childhood.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

Antibiotic use as a risk factor for inflammatory bowel disease across the ages: a population-based cohort study

BACKGROUND

There is an increasing incidence of inflammatory bowel disease (IBD) for which environmental factors are suspected. Antibiotics have been associated with development of IBD in earlier generations, but their influence on IBD risk in adults is uncertain.

OBJECTIVE

To assess the impact of antibiotic exposure, including dose-response, timing and antibiotic class, on the risk of IBD in all individuals aged ≥10 years.

DESIGN

Using Denmark nationwide registries, a population-based cohort of residents aged ≥10 years was established between 2000 and 2018. Incidence rate ratios (IRRs) for IBD following antibiotic exposure were calculated using Poisson regression.

RESULTS

There were a total of 6 104 245 individuals, resulting in 87 112 328 person-years of follow-up, and 52 898 new cases of IBD. Antibiotic exposure was associated with an increased risk of IBD as compared with no antibiotic exposure for all age groups, although was greatest among individuals aged 40-60 years and ≥60 years (age 10-40 years, IRR 1.28, 95% CI 1.25 to 1.32; age 40-60 years, IRR 1.48, 95% CI 1.43 to 1.54; age ≥60 years, IRR 1.47, 95% CI 1.42 to 1.53). For all age groups a positive dose-response was observed, with similar results seen for both ulcerative colitis and Crohn's disease. The highest risk of developing IBD was seen 1-2 years after antibiotic exposure, and after use of antibiotic classes often prescribed to treat gastrointestinal pathogens.

CONCLUSION

Antibiotic exposure is associated with an increased risk of IBD, and was highest among individuals aged 40 years and older. This risk increased with cumulative antibiotic exposure, with antibiotics targeting gastrointestinal pathogens and within 1-2 years after antibiotic exposure.

Macrolide antibiotics activate the integrated stress response and promote tumor proliferation

Macrolide antibiotics are widely used antibacterial agents that are associated with autophagy inhibition. This study aimed to investigate the association between macrolide antibiotics and malignant tumors, as well as the effect on autophagy, reactive oxygen species (ROS) accumulation and integrated stress response (ISR). The meta-analysis indicated a modestly higher risk of cancer in macrolide antibiotic ever-users compared to non-users. Further experiments showed that macrolides block autophagic flux by inhibiting lysosomal acidification. Additionally, azithromycin, a representative macrolide antibiotic, induced the accumulation of ROS, and stimulated the ISR and the activation of transcription factor EB (TFEB) and TFE3 in a ROS-dependent manner. Finally, animal experiments confirmed that azithromycin promoted tumor progression in vivo, which could be receded by N-acetylcysteine, an inhibitor of ROS and ISR. Overall, this study reveals the potential role of macrolide antibiotics in malignant progression and highlights the need for further investigation into their effects.

Global research on the crosstalk between intestinal microbiome and colorectal cancer: A visualization analysis

Background

Increasing evidence has shown that the intestinal microbiome (IM) is highly linked to colorectal cancer (CRC). To investigate scientific output, identify highly cited papers, and explore research hotspots and trends in the field of IM/CRC, we conducted a bibliometric and visualized analysis.

Methods

A bibliographic search regarding IM/CRC research (2012-2021) was implemented on October 17, 2022. The terms attached to IM and CRC were searched for in the titles (TI), abstracts (AB), and author keywords (AK). The main information was extracted from the Web of Science Core Collection (WoSCC). Biblioshiny from R packages and VOSviewer were used for data visualization.

Results

A total of 1725 papers related to IM/CRC were retrieved. Publications on IM/CRC have grown rapidly from 2012 to 2021. China and the United States were in the leading position for publications in this field and made the most significant contributions to IM/CRC research. Shanghai Jiao Tong University and Harvard University were the most productive institutions. The high-yield authors were Yu Jun and Fang Jing Yuan. The International Journal of Molecular Sciences published the most papers, whereas Gut had the most citations. Historical citation analysis showed the evolution of IM/CRC research. Current status and hotspots were highlighted using keyword cluster analysis. The hot topics include the effect of IM on tumorigenesis, the effect of IM on CRC treatment, the role of IM in CRC screening, the mechanisms of IM involvement in CRC, and IM modulation for CRC management. Some topics, such as chemotherapy, immunotherapy, Fusobacterium nucleatum and short-chain fatty acids could be the focus of IM/CRC research in the coming years.

Conclusion

This research evaluated the global scientific output of IM/CRC research and its quantitative features, identified some significant papers, and gathered information on the status and trends of IM/CRC research, which may shape future paths for academics and practitioners.

A systematic analysis of the global and regional burden of colon and rectum cancer and the difference between early- and late-onset CRC from 1990 to 2019

The burden of colorectal cancer (CRC) varies substantially across different geographical locations. However, there was no further quantitative analysis of regional social development and the disease burden of CRC. In addition, the incidence of early- and late-onset CRC has increased rapidly in developed and developing regions. The main purpose of this study was to investigate the trends in CRC burden across different regions, in addition to the epidemiological differences between early and late-onset CRC and their risk factors. In this study, estimated annual percentage change (EAPC) was employed to quantify trends in age-standardized incidence rate (ASIR), mortality rate, and disability-adjusted life-years. Restricted cubic spline models were fitted to quantitatively analyze the relationship between trends in ASIR and Human Development Index (HDI). In addition, the epidemiological characteristics of early- and late-onset CRC were investigated using analyses stratified by age groups and regions. Specifically, meat consumption and antibiotic use were included to explore the differences in the risk factors for early- and late-onset CRC. The quantitative analysis showed that the ASIR of CRC was exponentially and positively correlated with the 2019 HDI in different regions. In addition, the growing trend of ASIR in recent years varied substantially across HDI regions. Specifically, the ASIR of CRC showed a significant increase in developing countries, while it remained stable or decreased in developed countries. Moreover, a linear correlation was found between the ASIR of CRC and meat consumption in different regions, especially in developing countries. Furthermore, a similar correlation was found between the ASIR and antibiotic use in all age groups, with different correlation coefficients for early-onset and late-onset CRC. It is worth mentioning that the early onset of CRC could be attributable to the unrestrained use of antibiotics among young people in developed countries. In summary, for better prevention and control of CRC, governments should pay attention to advocate self-testing and hospital visits among all age groups, especially among young people at high risk of CRC, and strictly control meat consumption and the usage of antibiotics.

Intake of Pro- and/or Prebiotics as a Promising Approach for Prevention and Treatment of Colorectal Cancer

Colorectal cancer (CRC) is the third most common type of cancer, posing a serious threat to human life. It is widely believed that dietary factors may be crucial modifiers of CRC risk, with pro-and/or prebiotics being especially promising. In this review, a synthesis of CRC prevention and treatment of strategies relying on usage of pro- and/or prebiotics supplements is given, as well as discuss mechanisms underlying the contribution of pro-and/or prebiotics to the suppression of colonic carcinogenesis. Furthermore, a framework for personalizing such supplements according to the composition of an individual's gut microbiome is suggested. Various factors including diversity of one's intestinal microflora, integrity of their intestinal barrier, and the presence of mutagenic/carcinogenic/genotoxic and beneficial compounds are known to have a prominent influence on the development of CRC; thus, clarifying the role of pro- and/or prebiotics will yield valuable insight toward optimizing interventions for enhanced patient outcomes in the future.

Cystic Fibrosis-Related Gut Dysbiosis: A Systematic Review

BACKGROUND AND AIMS

Cystic Fibrosis (CF) is associated with gut dysbiosis, local and systemic inflammation, and impaired immune function. Gut microbiota dysbiosis results from changes in the complex gut milieu in response to CF transmembrane conductance regulator (CFTR) dysfunction, pancreatic malabsorption, diet, medications, and environmental influences. In several diseases, alteration of the gut microbiota influences local and systemic inflammation and disease outcomes. We conducted a systematic review of the gut microbiota in CF and explored factors influencing dysbiosis.

METHODS

An electronic search of three databases was conducted in January 2019, and re-run in June 2021. Human, animal, and in vitro studies were included. The primary outcome was differences in the gut microbiota between people with CF (pwCF) and healthy controls. Secondary outcomes included the relationship between the gut microbiota and other factors, including diet, medication, inflammation, and pulmonary function in pwCF.

RESULTS

Thirty-eight studies were identified. The literature confirmed the presence of CF-related gut dysbiosis, characterized by reduced diversity and several taxonomic changes. There was a relative increase of bacteria associated with a pro-inflammatory response coupled with a reduction of those considered anti-inflammatory. However, studies linking gut dysbiosis to systemic and lung inflammation were limited. Causes of gut dysbiosis were multifactorial, and findings were variable. Data on the impact of CFTR modulators on the gut microbiota were limited.

CONCLUSIONS

CF-related gut dysbiosis is evident in pwCF. Whether this influences local and systemic disease and is amenable to interventions with diet and drugs, such as CFTR modulators, requires further investigation.

Colorectal cancer and gut microbiota studies in China

Colorectal cancer (CRC) is the third most common malignant tumor worldwide. The incidence and mortality rates of CRC have been increasing in China, possibly due to economic development, lifestyle, and dietary changes. Evidence suggests that gut microbiota plays an essential role in the tumorigenesis of CRC. Gut dysbiosis, specific pathogenic microbes, metabolites, virulence factors, and microbial carcinogenic mechanisms contribute to the initiation and progression of CRC. Gut microbiota biomarkers have potential translational applications in CRC screening and early diagnosis. Gut microbiota-related interventions could improve anti-tumor therapy's efficacy and severe intestinal toxic effects. Chinese researchers have made many achievements in the relationship between gut microbiota and CRC, although some challenges remain. This review summarizes the current evidence from China on the role of gut microbiota in CRC, mainly including the gut microbiota characteristics, especially Fusobacterium nucleatum and Parvimonas micra, which have been identified to be enriched in CRC patients; microbial pathogens such as F. nucleatum and enterotoxigenic Bacteroides fragilis, and P. micra, which Chinese scientists have extensively studied; diagnostic biomarkers especially F. nucleatum; therapeutic effects, including microecological agents represented by certain Lactobacillus strains, fecal microbiota transplantation, and traditional Chinese medicines such as Berberine and Curcumin. More efforts should be focused on exploring the underlying mechanisms of microbial pathogenesis of CRC and providing novel gut microbiota-related therapeutic and preventive strategies.

Dysbiosis: The first hit for digestive system cancer

Gastrointestinal cancer may be associated with dysbiosis, which is characterized by an alteration of the gut microbiota. Understanding the role of gut microbiota in the development of gastrointestinal cancer is useful for cancer prevention and gut microbiota-based therapy. However, the potential role of dysbiosis in the onset of tumorigenesis is not fully understood. While accumulating evidence has demonstrated the presence of dysbiosis in the intestinal microbiota of both healthy individuals and patients with various digestive system diseases, severe dysbiosis is often present in patients with digestive system cancer. Importantly, specific bacteria have been isolated from the fecal samples of these patients. Thus, the association between dysbiosis and the development of digestive system cancer cannot be ignored. A new model describing this relationship must be established. In this review, we postulate that dysbiosis serves as the first hit for the development of digestive system cancer. Dysbiosis-induced alterations, including inflammation, aberrant immune response, bacteria-produced genotoxins, and cellular stress response associated with genetic, epigenetic, and/or neoplastic changes, are second hits that speed carcinogenesis. This review explains the mechanisms for these four pathways and discusses gut microbiota-based therapies. The content included in this review will shed light on gut microbiota-based strategies for cancer prevention and therapy.

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.

Assessment of the In Vitro Cytotoxic Profile of Two Broad-Spectrum Antibiotics-Tetracycline and Ampicillin-On Pharyngeal Carcinoma Cells

Background and Objectives: In spite of the fact that antibiotics are considered to be the cornerstone of modern medicine, their use in the treatment of cancer remains controversial. In the present study, the main objective was to examine the effects of two antibiotics—tetracycline and ampicillin—on the viability, morphology, migration, and organization and structure of the nuclei and the actin fiber network of pharyngeal carcinoma cells—Detroit-562. Materials and Methods: In order to determine the viability of the cells, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method was applied after the cells were stimulated with five concentrations of tetracycline and ampicillin (10, 25, 50, 75, and 100 μM) for 72 h. A scratch assay was used to assess the migration ability of the cells. For the visualization of the nuclei and actin fibers, 4,6-diamidino-2-phenylindole (Dapi) and Rhodamine-Phalloidin were used. Results: There are different effects of tetracycline and ampicillin. Thus, tetracycline: (i) exhibited a concentration-dependent cytotoxic effect, decreasing cell viability to approximately 46%; (ii) inhibits cellular migration up to 16% compared to 60% for control cells; and (iii) induces changes in cell morphology as well as apoptotic changes in the nucleus and F-actin fibers. In contrast, in the case of ampicillin, an increase in viability up to 113% was observed at 10 μM, while a decrease in viability up to approximately 94% was observed at the highest concentration tested (100 μM). Conclusions: The results indicated a different effect regarding the impact on pharyngeal carcinoma cells. Thus, tetracycline has a concentration-dependent cytotoxic effect, while in the case of ampicillin a slight stimulation of cell viability was observed.

Colorectal Cancer in Younger Adults

Contrary to decreasing incidence rate of colorectal cancer (CRC) in older adults, incidence rates have nearly doubled in younger adults (age <50 years) in the United States since the early 1990s. A similar increase has been observed across the globe. Despite overall population trends in aging, about 15% of CRCs will be diagnosed in younger adults by 2030. The mechanisms and factors contributing to early-onset CRC (EOCRC) remain puzzling, especially because most young adults diagnosed with CRC have no known risk factors or predisposing conditions, such as family history of CRC or polyps or a hereditary syndrome (eg, Lynch syndrome, polyposis). In this up-to-date review, we discuss the current knowledge of EOCRC, including epidemiology, risk factors, clinical and molecular features, treatment and survival, and recognition and screening strategies.

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.

Next-generation sequencing: insights to advance clinical investigations of the microbiome

Next-generation sequencing (NGS) technology has advanced our understanding of the human microbiome by allowing for the discovery and characterization of unculturable microbes with prediction of their function. Key NGS methods include 16S rRNA gene sequencing, shotgun metagenomic sequencing, and RNA sequencing. The choice of which NGS methodology to pursue for a given purpose is often unclear for clinicians and researchers. In this Review, we describe the fundamentals of NGS, with a focus on 16S rRNA and shotgun metagenomic sequencing. We also discuss pros and cons of each methodology as well as important concepts in data variability, study design, and clinical metadata collection. We further present examples of how NGS studies of the human microbiome have advanced our understanding of human disease pathophysiology across diverse clinical contexts, including the development of diagnostics and therapeutics. Finally, we share insights as to how NGS might further be integrated into and advance microbiome research and clinical care in the coming years.

A Summary of the Sixth International Workshop on Microbiome in HIV Pathogenesis, Prevention, and Treatment

In October of 2020, researchers from around the world met online for the sixth annual International Workshop on Microbiome in HIV Pathogenesis, Prevention, and Treatment. New research was presented on the roles of the microbiome on immune response and HIV transmission and pathogenesis and the potential for alterations in the microbiome to decrease transmission and affect comorbidities. This article presents a summary of the findings reported.

Modulatory Effects of Biosynthesized Gold Nanoparticles Conjugated with Curcumin and Paclitaxel on Tumorigenesis and Metastatic Pathways-In Vitro and In Vivo Studies

Background: Breast cancer is the most common cancer in women globally, and diagnosing it early and finding potential drug candidates against multi-drug resistant metastatic breast cancers provide the possibilities of better treatment and extending life. Methods: The current study aimed to evaluate the synergistic anti-metastatic activity of Curcumin (Cur) and Paclitaxel (Pacli) individually, the combination of Curcumin–Paclitaxel (CP), and also in conjugation with gold nanoparticles (AuNP–Curcumin (Au-C), AuNP–Paclitaxel (Au-P), and AuNP–Curcumin–Paclitaxel (Au-CP)) in various in vitro and in vivo models. Results: The results from combination treatments of CP and Au-CP demonstrated excellent synergistic cytotoxic effects in triple-negative breast cancer cell lines (MDA MB 231 and 4T1) in in vitro and in vivo mouse models. Detailed mechanistic studies were performed that reveal that the anti-cancer effects were associated with the downregulation of the expression of VEGF, CYCLIN-D1, and STAT-3 genes and upregulation of the apoptotic Caspase-9 gene. The group of mice that received CP combination therapy (with and without gold nanoparticles) showed a significant reduction in the size of tumor when compared to the Pacli alone treatment and control groups. Conclusions: Together, the results suggest that the delivery of gold conjugated Au-CP formulations may help in modulating the outcomes of chemotherapy. The present study is well supported with observations from cell-based assays, molecular and histopathological analyses.

Antibiotic Therapy and Risk of Early-Onset Colorectal Cancer: A National Case-Control Study

INTRODUCTION

Antibiotic use has emerged as a risk factor for colorectal neoplasia and is hypothesized as a contributor to the rising incidence of colorectal cancer under age 50 years or early-onset colorectal cancer (EOCRC). However, the impact of antibiotic use and risk of EOCRC is unknown.

METHODS

We conducted a population-based case-control study of CRC among individuals aged ≥18 years in the Epidemiology Strengthened by histoPathology Reports in Sweden (ESPRESSO) cohort (2006-2016). The primary outcome was EOCRC. A secondary outcome was CRC at any age. Incident CRC was pathologically confirmed, and for each, up to 5 population-based controls were matched on age, sex, county of residence, and calendar year. We assessed prescriptions until 6 months before CRC diagnosis. Conditional logistic regression was used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

We identified 54,804 cases of CRC (2,557 EOCRCs) and 261,089 controls. Compared with none, previous antibiotic use was not associated with EOCRC risk after adjustment for potential confounders (aOR 1.06, 95% CI: 0.96, 1.17) with similarly null findings when stratified by anatomic tumor site. In contrast, previous antibiotic use was weakly associated with elevated risk for CRC at any age (aOR 1.05, 95% CI: 1.02, 1.07). A potential but modest link between broad-spectrum antibiotic use and EOCRC was observed (aOR 1.13, 95% CI: 1.02, 1.26).

DISCUSSION

We found no conclusive evidence that antibiotics are associated with EOCRC risk. Although antibiotic use was weakly associated with risk of CRC at any age, the magnitude of association was modest, and the study period was relatively short.

Polystyrene nanoplastics exacerbated the ecotoxicological and potential carcinogenic effects of tetracycline in juvenile grass carp (Ctenopharyngodon idella)

This study aims to evaluate the ecotoxicity effects of single tetracycline (TC) exposure and mixture exposure in presence of polystyrene nanoplastics (PS-NPs, 80 nm) on juvenile Ctenopharyngodon idella. We carried out single and combined exposure of TC (5000 μg/L) and PS-NPs (20, 200, 2000 μg/L) for 7 days. Compared to TC single exposure, co-exposure to PS-NPs and TC significantly changed the levels of antioxidant entities, including T-AOC, SOD, and CAT in the liver and intestine of C. idella, indicating that PS-NPs might enhance the oxidative damage caused by TC. Further, the co-exposure significantly upregulated the mRNA expression levels of MMP2, MMP9, and IL-8 in a concentration-dependent manner in the liver and intestine tissues of C. idella, compared to the control and TC single exposure groups. Moreover, the phylogenetic tree showed that MMP2 and MMP9 in C. idella are relatively conservative, and the mRNA expressions of MMP2 are significantly positively correlated with TGFβ1, IL8, and MMP9 in Liver hepatocellular carcinoma (LIHC) and Colon adenocarcinoma (COAD). The above genes in LIHC and COAD were significantly correlated with various immune cells. Further, histopathological analysis revealed tissue lesions in the intestine and gill of fish in all the exposed groups, compared to the control group. In short, the present study illustrated that the toxicological effects of organic pollutants such as TC could be influenced by the presence of NPs in the C. idella.

Gastrointestinal Adenocarcinoma Incidence and Survival Trends in South Australia, 1990-2017

Simple Summary

This study from South Australia using the state’s Cancer Registry data provides compelling evidence for a significant increase in the incidence of young-onset (18–50 years) gastrointestinal (oesophageal, stomach, colon and rectum, and pancreas) adenocarcinomas over the last three decades. The trend observed in the young cohort was not mirrored in older individuals >50 years. This increased incidence, though noted in both sexes, was more pronounced in males compared to females. Survival in the young-onset adenocarcinoma cohort was only seen in patients with colorectal cancers, but not oesophagus, stomach and pancreas. This study calls for a concerted effort aimed at determining the sociodemographic factors underlying this disturbing trend with the aim of developing preventative strategies.

Abstract

Background & Aims: Globally, there has been a concerning rise in the incidence of young-onset cancers. The aim of this study was to provide trends in the incidence and survival of gastrointestinal adenocarcinomas (oesophagus, stomach, pancreas, and colorectal) in South Australia over a 27-year period. Methods: This is a cross-sectional analysis of a prospective longitudinal database including all cases of gastrointestinal adenocarcinomas prospectively reported to the South Australian (State) Cancer Registry from 1990 to 2017. Results: A total of 28,566 patients diagnosed with oesophageal, stomach, pancreatic, or colorectal adenocarcinoma between 1990 and 2017 were included in the study. While the overall incidence for gastrointestinal adenocarcinomas in individuals >50 years has decreased since 2000 (IRR of 0.97 (95% CI 0.94–1.00; p = 0.06)) compared to 1990–1999, the rate amongst individuals aged 18–50 has significantly increased (IRR 1.41 (95% CI 1.27–1.57; p < 0.001)) during the same reference time period. Although noted in both sexes, the rate of increase in incidence was significantly greater in males (11.5 to 19.7/100,000; p < 0.001). The overall survival from adenocarcinomas across all subsites improved in the >50-year cohort in the last decade (HR 0.89 (95% CI 0.86–0.93; p < 0.001)) compared to 1990–1999. In individuals aged 18–50 years, there has only been a significant improvement in survival for colorectal cancer (HR 0.82 (95% CI 0.68–0.99; p < 0.04)), but not the other subsites. A lower overall survival was noted for males in both age cohorts (18–50 years—HR 1.24 (95% CI 1.09–1.13; p < 0.01) and >50 years—HR 1.13 (95% CI 1.10–1.16; p < 0.001), respectively) compared to females. Conclusions: This study from South Australia demonstrates a significant increase in young-onset gastrointestinal adenocarcinomas over the last 28 years, with a greater increase in the male sex. The only significant improvement in survival in this cohort has been noted in colorectal cancer patients.

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.