Microbiota Biomarkers for Lung Cancer

Microbes for lung cancer detection: feasibility and limitations

As the second most common cancer in the world, the development of lung cancer is closely related to factors such as heredity, environmental exposure, and lung microenvironment, etc. Early screening and diagnosis of lung cancer can be helpful for the treatment of patients. Currently, CT screening and histopathologic biopsy are widely used in the clinical detection of lung cancer, but they have many disadvantages such as false positives and invasive operations. Microbes are another genome of the human body, which has recently been shown to be closely related to chronic inflammatory, metabolic processes in the host. At the same time, they are important players in cancer development, progression, treatment, and prognosis. The use of microbes for cancer therapy has been extensively studied, however, the diagnostic role of microbes is still unclear. This review aims to summarize recent research on using microbes for lung cancer detection and present the current shortcomings of microbes in collection and detection. Finally, it also looks ahead to the clinical benefits that may accrue to patients in the future about screening and early detection.

Acidovorax temperans skews neutrophil maturation and polarizes Th17 cells to promote lung adenocarcinoma development

Change within the intratumoral microbiome is a common feature in lung and other cancers and may influence inflammation and immunity in the tumor microenvironment, affecting growth and metastases. We previously characterized the lung cancer microbiome in patients and identified Acidovorax temperans as enriched in tumors. Here, we instilled A. temperans in an animal model driven by mutant K-ras and Tp53. This revealed A. temperans accelerates tumor development and burden through infiltration of proinflammatory cells. Neutrophils exposed to A. temperans displayed a mature, pro-tumorigenic phenotype with increased cytokine signaling, with a global shift away from IL-1β signaling. Neutrophil to monocyte and macrophage signaling upregulated MHC II to activate CD4+ T cells, polarizing them to an IL-17A+ phenotype detectable in CD4+ and γδ populations (T17). These T17 cells shared a common gene expression program predictive of poor survival in human LUAD. These data indicate bacterial exposure promotes tumor growth by modulating inflammation.

Composition of the sputum bacterial microbiome of patients with different pathomorphological forms of non-small-cell lung cancer

Recent studies have shown that the bacterial microbiome of the respiratory tract influences the development of lung cancer. Changes in the composition of the microbiome are observed in patients with chronic inflammatory processes. Such microbiome changes may include the occurrence of bacteria that cause oxidative stress and that are capable of causing genome damage in the cells of the host organism directly and indirectly. To date, the composition of the respiratory microbiome in patients with various histological variants of lung cancer has not been studied. In the present study, we determined the taxonomic composition of the sputum microbiome of 52 patients with squamous cell carcinoma of the lung, 52 patients with lung adenocarcinoma and 52 healthy control donors, using next-generation sequencing (NGS) on the V3-V4 region of the bacterial gene encoding 16S rRNA. The sputum microbiomes of patients with different histological types of lung cancer and controls did not show significant differences in terms of the species richness index (Shannon); however, the patients differed from the controls in terms of evenness index (Pielou). The structures of bacterial communities (beta diversity) in the adenocarcinoma and squamous cell carcinoma groups were also similar; however, when analyzed according to the matrix constructed by the Bray-Curtis method, there were differences between patients with squamous cell carcinoma and healthy subjects, but not between those with adenocarcinoma and controls. Using the LEFse method it was possible to identify an increase in the content of Bacillota (Streptococcus and Bacillus) and Actinomycetota (Rothia) in the sputum of patients with squamous cell carcinoma when compared with samples from patients with adenocarcinoma. There were no differences in the content of bacteria between the samples of patients with adenocarcinoma and the control ones. The content of representatives of the genera Streptococcus, Bacillus, Peptostreptococcus (phylum Bacillota), Prevotella, Macellibacteroides (phylum Bacteroidota), Rothia (phylum Actinomycetota) and Actinobacillus (phylum Pseudomonadota) was increased in the microbiome of sputum samples from patients with squamous cell carcinoma, compared with the control. Thus, the sputum bacterial microbiome of patients with different histological types of non-small-cell lung cancer has significant differences. Further research should be devoted to the search for microbiome biomarkers of lung cancer at the level of bacterial species using whole-genome sequencing.

Microbiome and lung cancer: carcinogenic mechanisms, early cancer diagnosis, and promising microbial therapies

Microbiomes in the lung, gut, and oral cavity are correlated with lung cancer initiation and progression. While correlations have been preliminarily established in earlier studies, delving into microbe-mediated carcinogenic mechanisms will extend our understanding from correlation to causation. Building upon the causative relationships between microbiome and lung cancer, a novel concept of microbial biomarkers has emerged, mainly encompassing cancer-specific bacteria and circulating microbiome DNA. They might function as noninvasive liquid biopsy techniques for lung cancer early detection. Furthermore, potential microbial therapies have displayed initial efficacy in lung cancer treatment, providing multiple avenues for therapeutic intervention. Herein, we will discuss the molecular mechanisms and signaling pathways through which microbes influence lung cancer initiation and development. Additionally, we will summarize recent findings on microbial biomarkers as a member of tumor liquid biopsy techniques and provide an overview of the latest advances in various microbe-assisted/mediated therapeutic approaches for lung cancer.

Symbiotic microbial communities in various locations of the lung cancer respiratory tract along with potential host immunological processes affected

Lung cancer has the highest mortality rate among all cancers worldwide. The 5-year overall survival rate for non-small cell lung cancer (NSCLC) is estimated at around 26%, whereas for small cell lung cancer (SCLC), the survival rate is only approximately 7%. This disease places a significant financial and psychological burden on individuals worldwide. The symbiotic microbiota in the human body has been significantly associated with the occurrence, progression, and prognosis of various diseases, such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. Studies have demonstrated that respiratory symbiotic microorganisms and their metabolites play a crucial role in modulating immune function and contributing to the pathophysiology of lung cancer through their interactions with the host. In this review, we provide a comprehensive overview of the microbial characteristics associated with lung cancer, with a focus on the respiratory tract microbiota from different locations, including saliva, sputum, bronchoalveolar lavage fluid (BALF), bronchial brush samples, and tissue. We describe the respiratory tract microbiota's biodiversity characteristics by anatomical region, elucidating distinct pathological features, staging, metastasis, host chromosomal mutations, immune therapies, and the differentiated symbiotic microbiota under the influence of environmental factors. Our exploration investigates the intrinsic mechanisms linking the microbiota and its host. Furthermore, we have also provided a comprehensive review of the immune mechanisms by which microbiota are implicated in the development of lung cancer. Dysbiosis of the respiratory microbiota can promote or inhibit tumor progression through various mechanisms, including DNA damage and genomic instability, activation and regulation of the innate and adaptive immune systems, and stimulation of epithelial cells leading to the upregulation of carcinogenesis-related pathways.

Comprehensive sampling of the lung microbiome in early-stage non-small cell lung cancer

Objectives

Data are scarce on whether the composition of the lung microbiome (extending from the nasopharynx to the peripheral lung tissue) varies according to histology or grade of non-small cell lung cancer. We hypothesized that the composition of the lung microbiome would vary according to the histology and the grade of non-small cell lung cancer.

Methods

We collected naso-oral and central lobar (cancer affected, ipsilateral unaffected, and contralateral unaffected) bronchoalveolar lavage fluid and brushing samples from patients with clinical early-stage lung cancer between July 2018 and February 2020 at a single academic center. We performed bacterial 16S rRNA sequencing and then compared clinical and pathologic findings with microbiome signatures.

Results

Samples were collected from 28 patients. Microbial composition in affected lobes displayed unique enrichment of oropharyngeal bacterial species that was significantly different compared with that from the unaffected contralateral lobes; patients with chronic obstructive pulmonary disease had similar diversity to those without chronic obstructive pulmonary disease (P = .1312). The lung microbiome diversity in patients with adenocarcinoma was similar to those with squamous cell cancer (P = .27). There were no differences in diversity or composition in the unaffected lobes of patients with adenocarcinoma versus squamous cell cancer. There was a trend toward lower lung microbial diversity in poorly differentiated adenocarcinomas compared with well-differentiated adenocarcinomas (P = .08).

Conclusions

The lung microbiota differs between cancer affected and unaffected lobes in the same patient. Furthermore, poorly differentiated lung cancers were associated with lower microbial diversity. Larger studies will be required to confirm these findings.

[Relationship between Bacteria in the Lower Respiratory Tract/Lung Cancer and the Development of Lung Cancer as well as Its Clinical Application]

Due to the advancement of 16S rRNA sequencing technology, the lower respiratory tract microbiota, which was considered non-existent, has been revealed. The correlation between these microorganisms and diseases such as tumor has been a hot topic in recent years. As the bacteria in the surrounding can infiltrate the tumors, researchers have also begun to pay attention to the biological behavior of tumor bacteria and their interaction with tumors. In this review, we present the characteristic of the lower respiratory tract bacteria and summarize recent research findings on the relationship between these microbiota and lung cancer. On top of that, we also summarize the basic feature of bacteria in tumors and focus on the characteristic of the bacteria in lung cancer. The relationship between bacteria in lung cancer and tumor development is also been discussed. Finally, we review the potential clinical applications of bacterial communities in the lower respiratory tract and lung cancer, and summarize key points of sample collection, sequencing, and contamination control, hoping to provide new ideas for the screening and treatment of tumors.
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The human microbiome and cancer: a diagnostic and therapeutic perspective

Recent evidence has shown that the human microbiome is associated with various diseases, including cancer. The salivary microbiome, fecal microbiome, and circulating microbial DNA in blood plasma have all been used experimentally as diagnostic biomarkers for many types of cancer. The microbiomes present within local tissue, other regions, and tumors themselves have been shown to promote and restrict the development and progression of cancer, most often by affecting cancer cells or the host immune system. These microbes have also been shown to impact the efficacy of various cancer therapies, including radiation, chemotherapy, and immunotherapy. Here, we review the research advances focused on how microbes impact these different facets and why they are important to the clinical care of cancer. It is only by better understanding the roles these microbes play in the diagnosis, development, progression, and treatment of cancer, that we will be able to catch and treat cancer early.

Mechanisms underlying the effects, and clinical applications, of oral microbiota in lung cancer: current challenges and prospects

The oral cavity contains a site-specific microbiota that interacts with host cells to regulate many physiological processes in the human body. Emerging evidence has suggested that changes in the oral microbiota can increase the risk of lung cancer (LC), and the oral microbiota is also altered in patients with LC. Human and animal studies have shown that oral microecological disorders and/or specific oral bacteria may play an active role in the occurrence and development of LC through direct and/or indirect mechanisms. These studies support the potential of oral microbiota in the clinical treatment of LC. Oral microbiota may therefore be used in the prevention and treatment of LC and to improve the side effects of anticancer therapy by regulating the balance of the oral microbiome. Specific oral microbiota in LC may also be used as screening or predictive biomarkers. This review summarizes the main findings in research on oral microbiome-related LC and discusses current challenges and future research directions.

Microbiomes, Their Function, and Cancer: How Metatranscriptomics Can Close the Knowledge Gap

The interaction between the microbial communities in the human body and the onset and progression of cancer has not been investigated until recently. The vast majority of the metagenomics research in this area has concentrated on the composition of microbiomes, attempting to link the overabundance or depletion of certain microorganisms to cancer proliferation, metastatic behaviour, and its resistance to therapies. However, studies elucidating the functional implications of the microbiome activity in cancer patients are still scarce; in particular, there is an overwhelming lack of studies assessing such implications directly, through analysis of the transcriptome of the bacterial community. This review summarises the contributions of metagenomics and metatranscriptomics to the knowledge of the microbial environment associated with several cancers; most importantly, it highlights all the advantages that metatranscriptomics has over metagenomics and suggests how such an approach can be leveraged to advance the knowledge of the cancer bacterial environment.

Identification of microbial markers associated with lung cancer based on multi-cohort 16 s rRNA analyses: A systematic review and meta-analysis

BACKGROUND

The relationship between commensal microbiota and lung cancer (LC) has been studied extensively. However, developing replicable microbiological markers for early LC diagnosis across multiple populations has remained challenging. Current studies are limited to a single region, single LC subtype, and small sample size. Therefore, we aimed to perform the first large-scale meta-analysis for identifying micro biomarkers for LC screening by integrating gut and respiratory samples from multiple studies and building a machine-learning classifier.

METHODS

In total, 712 gut and 393 respiratory samples were assessed via 16 s rRNA amplicon sequencing. After identifying the taxa of differential biomarkers, we established random forest models to distinguish between LC populations and normal controls. We validated the robustness and specificity of the model using external cohorts. Moreover, we also used the KEGG database for the predictive analysis of colony-related functions.

RESULTS

The α and β diversity indices indicated that LC patients' gut microbiota (GM) and lung microbiota (LM) differed significantly from those of the healthy population. Linear discriminant analysis (LDA) of effect size (LEfSe) helped us identify the top-ranked biomarkers, Enterococcus, Lactobacillus, and Escherichia, in two microbial niches. The area under the curve values of the diagnostic model for the two sites were 0.81 and 0.90, respectively. KEGG enrichment analysis also revealed significant differences in microbiota-associated functions between cancer-affected and healthy individuals that were primarily associated with metabolic disturbances.

CONCLUSIONS

GM and LM profiles were significantly altered in LC patients, compared to healthy individuals. We identified the taxa of biomarkers at the two loci and constructed accurate diagnostic models. This study demonstrates the effectiveness of LC-specific microbiological markers in multiple populations and contributes to the early diagnosis and screening of LC.

The Lung Microbiome in COPD and Lung Cancer: Exploring the Potential of Metal-Based Drugs

Chronic obstructive pulmonary disease (COPD) and lung cancer 17 are two of the most prevalent and debilitating respiratory diseases worldwide, both associated with high morbidity and mortality rates. As major global health concerns, they impose a substantial burden on patients, healthcare systems, and society at large. Despite their distinct aetiologies, lung cancer and COPD share common risk factors, clinical features, and pathological pathways, which have spurred increasing research interest in their co-occurrence. One area of particular interest is the role of the lung microbiome in the development and progression of these diseases, including the transition from COPD to lung cancer. Exploring novel therapeutic strategies, such as metal-based drugs, offers a potential avenue for targeting the microbiome in these diseases to improve patient outcomes. This review aims to provide an overview of the current understanding of the lung microbiome, with a particular emphasis on COPD and lung cancer, and to discuss the potential of metal-based drugs as a therapeutic strategy for these conditions, specifically concerning targeting the microbiome.

Uncovering the special microbiota associated with occurrence and progression of gastric cancer by using RNA-sequencing

Gastric cancer (GC) has been identified as the third deadly cancer in the world. Accumulating researches suggest a potential role of microorganisms in tumorigenesis. However, the composition of microbiota in GC tissues is not clear and it changes throughout the different stages of GC remain mostly elusive. Our study integrated RNA-Seq data of 727 samples derived from gastric tissues across four datasets and revealed its microbial composition. In order to remove the false positive results, core taxa were defined and characterized. Based on it, we analyzed the influence of biological factors on its composition. The pan-microbiome of gastric tissues was estimated to be over than 1400 genera. Seventeen core genera were identified. Among them, Helicobacter, Lysobacter were significantly enriched in normal tissues, while Pseudomonas was enriched in tumor tissues. Interestingly, Acinetobacter, Pasteurella, Streptomyces, Chlamydia, and Lysobacter, showed a significant increase trend during tumor development and formed strong intra/inter-correlations among them or with other genera. Furthermore, we found that tumor stage played an important role in altering the microbial composition of GC tissues. This study provides support for the in-depth study of tumor microbiome, and the specific microbiome excavated provides a possibility for the subsequent identification of potential biomarkers for GC.

Lung microbiome: an emerging player in lung cancer pathogenesis and progression

The microbiome of the lungs, although until recently neglected, is now emerging as a potential contributor to chronic lung diseases, including cancer. Preclinical evidence suggests that the microbial burden of the lungs shapes the host immunity mechanisms and affects local antitumor immune responses. Studies of cohorts of patients with lung cancer reveal that different microbiome profiles are detected in patients with lung cancer compared to controls. In addition, an association between differential lung microbiome composition and distinct responses to immunotherapy has been suggested, yet, with limited data. Scarce evidence exists on the role of the lung microbiome in the development of metastases in the lungs. Interestingly, the lung microbiome is not isolated and interacts with the gut microbiome through a dynamic axis. Future research on the involvement of the lung microbiome in lung cancer pathogenesis and potential therapeutic implications is greatly anticipated.

Lower respiratory tract microbiome composition and community interactions in smokers

The lung microbiome impacts on lung function, making any smoking-induced changes in the lung microbiome potentially significant. The complex co-occurrence and co-avoidance patterns between the bacterial taxa in the lower respiratory tract (LRT) microbiome were explored for a cohort of active (AS), former (FS) and never (NS) smokers. Bronchoalveolar lavages (BALs) were collected from 55 volunteer subjects (9 NS, 24 FS and 22 AS). The LRT microbiome composition was assessed using 16S rRNA amplicon sequencing. Identification of differentially abundant taxa and co-occurrence patterns, discriminant analysis and biomarker inferences were performed. The data show that smoking results in a loss in the diversity of the LRT microbiome, change in the co-occurrence patterns and a weakening of the tight community structure present in healthy microbiomes. The increased abundance of the genus Ralstonia in the lung microbiomes of both former and active smokers is significant. Partial least square discriminant and DESeq2 analyses suggested a compositional difference between the cohorts in the LRT microbiome. The groups were sufficiently distinct from each other to suggest that cessation of smoking may not be sufficient for the lung microbiota to return to a similar composition to that of NS. The linear discriminant analysis effect size (LEfSe) analyses identified several bacterial taxa as potential biomarkers of smoking status. Network-based clustering analysis highlighted different co-occurring and co-avoiding microbial taxa in the three groups. The analysis found a cluster of bacterial taxa that co-occur in smokers and non-smokers alike. The clusters exhibited tighter and more significant associations in NS compared to FS and AS. Higher degree of rivalry between clusters was observed in the AS. The groups were sufficiently distinct from each other to suggest that cessation of smoking may not be sufficient for the lung microbiota to return to a similar composition to that of NS.

Circulating Bacterial DNA as Plasma Biomarkers for Lung Cancer Early Detection

Lung cancer is a leading cause of cancer deaths and early diagnosis can significantly improve outcomes. Pathogenic bacteria have been shown to play a role in tumorigenesis and its analysis provides a new approach for cancer diagnosis. To evaluate the potential of bacteria as plasma biomarkers for early lung cancer detection, we analyzed eight lung-cancer-related bacterial genera in 58 lung cancer patients and 58 controls using ddPCR. Our results showed that five genera had higher DNA abundance in lung tumor tissues compared with normal tissues. Three of these genera (Selenomonas, Streptococcus, and Veillonella) displayed consistent changes in plasma, with higher DNA abundance in lung cancer patients compared with controls. When used as a panel, these three bacterial genera had a sensitivity of 75% and specificity of 78% for lung cancer detection, regardless of stage or histology. The performance of this biomarker panel was confirmed in an independent cohort of 93 lung cancer cases and 93 controls. Thus, circulating bacterial DNA has the potential to be used as plasma biomarkers for early lung cancer detection.

The human microbiome: A promising target for lung cancer treatment

Lung cancer is the leading cause of cancer-related deaths worldwide, and insights into its underlying mechanisms as well as potential therapeutic strategies are urgently needed. The microbiome plays an important role in human health, and is also responsible for the initiation and progression of lung cancer through its induction of inflammatory responses and participation in immune regulation, as well as for its role in the generation of metabolic disorders and genotoxicity. Here, the distribution of human microflora along with its biological functions, the relationship between the microbiome and clinical characteristics, and the role of the microbiome in clinical treatment of lung cancer were comprehensively reviewed. This review provides a basis for the current understanding of lung cancer mechanisms with a focus on the microbiome, and contributes to future decisions on treatment management.

Microbial Biomarkers for Lung Cancer: Current Understandings and Limitations

As our "hidden organ", microbes widely co-exist at various sites on the human body. These microbes are collectively referred to as the microbiome. A considerable number of studies have already proven that the microbiome has significant impacts on human health and disease progression, including cancers. The recent discovery of cancer-specific microbiomes renders these cancer-associated microbes as potential biomarkers and therapeutic targets. While at low biomass levels, the lung microbiome still dramatically influences the initiation, progression and treatment of lung cancers. However, research on lung cancer-associated microbiomes is emerging, and most profiling studies are performed within three years. Unfortunately, there are substantial inconsistencies across these studies. Variations in microbial diversity were observed, and different microbial biomarkers for lung cancer have been proposed. In this review, we summarized the current findings of lung cancer microbiome studies and attempt to explain the potential reasons for the dissimilarities. Other than lung microbiomes, oral and airway microbiomes are highly related to lung microbiomes and are therefore included as well. In addition, several lung cancer-associated bacterial genera have been detected by different independent studies. These bacterial genera may not be perfect biomarkers, but they still serve as promising risk factors for lung cancers and show great prognostic value.

Screening of potential microbial markers for lung cancer using metagenomic sequencing

INTRODUCTION

Lung cancer is the most prevalent cancer with high mortality in China, and it is associated with the dysbiosis of the lung microbiome. This study attempted to screen for specific microorganisms as potential biomarkers for distinguishing benign lung disease from lung cancer.

METHODS

Bronchoalveolar lavage fluid (BALF) sample was selected in the study instead of saliva to avoid contamination with oral microorganisms, and microbial taxonomic and functional differences in BALF samples from patients with lung cancer and those with those from patients with benign lung diseases were performed based on metagenomic next-generation sequencing, for the first time, so that microorganisms other than bacteria could be included.

RESULTS

The results showed that the intrasample diversity of malignant samples was different from benign samples, and the microbial differences among malignant samples were smaller, with lower microbial diversity, significantly changed microbial abundance and metabolic functions. Metabolic function analysis revealed amino acid-related metabolism was more prevalent in benign samples, whereas carbohydrate-related metabolism was more prevalent in malignant samples. By LEfSe, Metastat and Random Forest analysis, we identified a series of important differential microorganisms. Importantly, the model combining five key genera plus one tumor marker (neuron-specific enolase) as indicators presented the optimal disease typing performance.

CONCLUSION

Thus results suggest the value of these differential microorganisms enriched in tumors in mechanism research and may be potential new targets for lung cancer therapy. More importantly, the biomarkers identified in this study can be conducive to improve the clinical diagnosis of lung cancer and have good application prospects.

The Lung Microbiota and Lung Cancer: A Growing Relationship

Simple Summary

In the past few years, the microbiota has emerged as a major player in cancer management. The efficacy of chemotherapy or immunotherapy may be influenced by the concomitant use of antibiotics before, during, or shortly after treatment with immune checkpoint inhibitors. Despite this, the mechanism linking the microbiota, host immunity, and malignancies are not clear, and the role of microbiota manipulation and analyses in cancer management is underway. In this manuscript, we discuss the role of the microbiota in the initiation, progression, and treatment outcomes of lung cancer.

Abstract

The lung is home to a dynamic microbial population crucial to modulating immune balance. Interest in the role of the lung microbiota in disease pathogenesis and treatment has exponentially increased. In lung cancer, early studies suggested an important role of dysbiosis in tumor initiation and progression. These results have helped accelerate research into the lung microbiota as a potential diagnostic marker and therapeutic target. Microbiota signatures could represent diagnostic biomarkers of early-stage disease. Lung microbiota research is in its infancy with a limited number of studies and only single-center studies with a significant methodological variation. Large, multicenter longitudinal studies are needed to establish the clinical potential of this exciting field.

Bacterial biomarkers capable of identifying recurrence or metastasis carry disease severity information for lung cancer

Background

Local recurrence and distant metastasis are the main causes of death in patients with lung cancer. Multiple studies have described the recurrence or metastasis of lung cancer at the genetic level. However, association between the microbiome of lung cancer tissue and recurrence or metastasis remains to be discovered. Here, we aimed to identify the bacterial biomarkers capable of distinguishing patients with lung cancer from recurrence or metastasis, and how it related to the severity of patients with lung cancer.

Methods

We applied microbiome pipeline to bacterial communities of 134 non-recurrence and non-metastasis (non-RM) and 174 recurrence or metastasis (RM) samples downloaded from The Cancer Genome Atlas (TCGA). Co-occurrence network was built to explore the bacterial interactions in lung cancer tissue of RM and non-RM. Finally, the Kaplan–Meier survival analysis was used to evaluate the association between bacterial biomarkers and patient survival.

Results

Compared with non-RM, the bacterial community of RM had lower richness and higher Bray–Curtis dissimilarity index. Interestingly, the co-occurrence network of non-RM was more complex than RM. The top 500 genera in relative abundance obtained an area under the curve (AUC) of 0.72 when discriminating between RM and non-RM. There were significant differences in the relative abundances of Acidovorax, Clostridioides, Succinimonas, and Shewanella, and so on between RM and non-RM. These biomarkers played a role in predicting the survival of lung cancer patients and were significantly associated with lung cancer stage.

Conclusion

This study provides the first evidence for the prediction of lung cancer recurrence or metastasis by bacteria in lung cancer tissue. Our results highlights that bacterial biomarkers that distinguish RM and non-RM are also associated with patient survival and disease severity.

Sputum Microbiome Composition in Patients with Squamous Cell Lung Carcinoma

Background: Recent findings indicate that the host microbiome can have a significant impact on the development of lung cancer by inducing an inflammatory response, causing dysbiosis, and generating genome damage. The aim of this study was to search for bacterial communities specifically associated with squamous cell carcinoma (LUSC). Methods: In this study, the taxonomic composition of the sputum microbiome of 40 men with untreated LUSC was compared with that of 40 healthy controls. Next-Generation sequencing of bacterial 16S rRNA genes was used to determine the taxonomic composition of the respiratory microbiome. Results: There were no differences in alpha diversity between the LUSC and control groups. Meanwhile, differences in the structure of bacterial communities (β diversity) among patients and controls differed significantly in sputum samples (pseudo-F = 1.53; p = 0.005). Genera of Streptococcus, Bacillus, Gemella, and Haemophilus were found to be significantly enriched in patients with LUSC compared to the control subjects, while 19 bacterial genera were significantly reduced, indicating a decrease in beta diversity in the microbiome of patients with LUSC. Conclusions: Among other candidates, Streptococcus (Streptococcus agalactiae) emerges as the most likely LUSC biomarker, but more research is needed to confirm this assumption.

Biomarkers and the microbiome in the detection and treatment of early-stage non-small cell lung cancer

Lung cancer is one of the most common and deadly cancers in the world. However, over the last several years, research into lung cancer screening and novel therapeutic approaches have provided promise that earlier detection combined with new treatment strategies may result in significantly improved outcomes. Biomarkers will most certainly play a major role in identifying those who may benefit from, and how to apply, these new treatment strategies. Here we discuss potential biomarkers, including the microbiome, in both detection and treatment strategies for early stage lung cancer.

Dysbiosis of the Gut Microbiome Is Associated With Histopathology of Lung Cancer

Lung cancer is a malignancy with high incidence and mortality worldwide. Previous studies have shown that the gut microbiome plays an important role in the development and progression of metabolic cancers. However, data on the characteristics of the gut microbiome with different histopathology types of lung cancer remain scant. We collected stool samples from 28 healthy people (HP) and 61 lung cancer patients. The lung cancer patients were classified into three types according to their histopathology: Atypical Adenomatous Hyperplasia/Adenocarcinoma in situ (AAH/AIS), Minimally Invasive Adenocarcinoma (MIA), and Invasive Adenocarcinoma (IA). In addition, we employed 16S rRNA gene amplicon sequencing to analyze the characteristics of the gut microbiome in these patients. Our analysis revealed that the categorized cancer patients had unique intestinal flora characteristics, and had lower density and flora diversity compared to healthy people. Besides, the structure of the flora families and genera was more complex, and each group presented specific pathogenic microbiota. The patients in the AAH/AIS group and HP group had relatively similar flora structure compared with the IA and MIA groups. In addition, we identified several flora markers that showed significant changes with the development of lung cancer. Lung cancer gut microbiota showed a decrease in short-chain fatty acids (SCFAs) producing and anti-inflammatory bacteria compared to healthy people, while some pathogenic bacteria such as proinflammatory or tumor-promoting bacteria were more abundant in lung cancer patients. On the other hand, the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Clusters of Orthologous Group (COG) annotation demonstrated suppression of some dominant metabolism-related pathways in lung cancer. These findings provide new biomarkers for the diagnosis and prognostic assessment of lung cancer and lay the basis for novel targeted therapeutic strategies for the prevention and treatment of lung cancer.

De- "bug"-ing the microbiome in lung cancer

The identification of microbes enriched in the healthy lung has led to the compelling discovery that microbes may contribute to lung cancer pathogenesis. Here, we review the recent literature showing microbial associations with lung cancer as well as the functional features that have been identified in human and murine studies. Most biomarker data remain limited due to variable findings. However, multiple studies have found that lung tumors or ipsilateral airway samples have decreased α diversity compared to normal tissue. Specific genera, such as Veillonella and Streptococcus, were also found in association with lung tumors using multiple sampling methodologies. These microbes, which are generally found in the upper respiratory track, are associated with an IL-17 signature in the lung, potentially resulting in a pro-tumorigenic environment. Studies detailing these immune mechanisms are limited, and further investigation is necessary to delineate how these bacteria, their metabolites, and potentially tumor-associated neoantigens modulate the immune response in cancer.

The respiratory microbiome associated with chronic obstructive pulmonary disease comorbidity in non-small cell lung cancer

Background

Research has shown that some microbiomes are linked to cancer. Hence, we hypothesize that alterations in the respiratory microbiome might be associated with lung cancer.

Methods

Through droplet digital polymerase chain reaction analysis, we investigated the abundance of Acidovorax in surgically resected primary tumors and corresponding nontumor lung tissues obtained from 50 Japanese patients with non‐small cell lung cancer.

Results

The rate of positivity for Acidovorax in tumor and nontumor tissues was 44 and 26%, respectively. The abundance of Acidovorax in tumor tissues was significantly higher in patients with nonsquamous cell carcinoma complicated by chronic obstructive pulmonary disease (COPD) and those who relapsed after surgical resection (p < 0.05). In tumor tissues, the results of the univariate and multivariate analyses revealed that only COPD exerted a direct effect on the abundance of Acidovorax (p < 0.05). Furthermore, the presence of Acidovorax was high in lung cancer patients with COPD comorbidity (65%) and TP53 gene mutation; only one of the nontumor tissues was positive for Acidovorax. In patients with lung cancer complicated by COPD, Acidovorax tended to be present in both the tumor and nontumor areas.

Conclusions

This study identified novel microbiota involved in lung cancer with COPD comorbidity. The results suggested that Acidovorax may be a useful biomarker in the screening for lung cancer. Further studies are warranted to validate the clinical significance of the microbiome in a larger independent patient cohort.

The emerging role of the lung microbiome and its importance in non-small cell lung cancer diagnosis and treatment

Over the last 10 years, with the development of culture-free bacterial identification techniques, understanding of how the microbiome influences diseases has increased exponentially and has highlighted potential opportunities for its use as a diagnostic biomarker and interventional target in many diseases including malignancy. Initial research focused on the faecal microbiome since it contains the densest bacterial populations and many other mucosal sites, such as the lungs, were until recently thought to be sterile. However, in recent years, it has become clear that the lower airways are home to a dynamic bacterial population sustained by the migration and elimination of microbes from the gastrointestinal and upper airway tracts. As in the gut, the lung microbiome plays an important role in regulating mucosal immunity and maintaining the balance between immune tolerance and inflammation. Studies to date have all shown that the lung microbiome undergoes significant changes in the setting of pulmonary disease. In lung cancer, animal models and small patient cohort studies have suggested that microbiome dysbiosis may not only impact tumour progression and response to therapy, particularly immunotherapy, but also plays a key role in cancer pathogenesis by influencing early carcinogenic pathways. These early results have led to concerted efforts to identify microbiome signatures that represent diagnostic biomarkers of early-stage disease and to consider modulation of the lung microbiome as a potential therapeutic strategy. Lung microbiome research is in its infancy and studies to date have been small, single centre with significant methodological variation. Large, multicentre longitudinal studies are needed to establish the clinical potential of this exciting field.