Use of probiotics for prevention of radiation-induced diarrhea

The Gut Connection: Exploring the Possibility of Implementing Gut Microbial Metabolites in Lymphoma Treatment

Recent research has implicated the gut microbiota in the development of lymphoma. Dysbiosis of the gut microbial community can disrupt the production of gut microbial metabolites, thereby impacting host physiology and potentially contributing to lymphoma. Dysbiosis-driven release of gut microbial metabolites such as lipopolysaccharides can promote chronic inflammation, potentially elevating the risk of lymphoma. In contrast, gut microbial metabolites, such as short-chain fatty acids, have shown promise in preclinical studies by promoting regulatory T-cell function, suppressing inflammation, and potentially preventing lymphoma. Another metabolite, urolithin A, exhibited immunomodulatory and antiproliferative properties against lymphoma cell lines in vitro. While research on the role of gut microbial metabolites in lymphoma is limited, this article emphasizes the need to comprehend their significance, including therapeutic applications, molecular mechanisms of action, and interactions with standard chemotherapies. The article also suggests promising directions for future research in this emerging field of connection between lymphoma and gut microbiome.

Effect of Lactobacillus Rhamnosus GG for Regulation of Inflammatory Response in Radiation-Induced Enteritis

The purpose of this study was to investigate the role of Lactobacillus rhamnosus GG (LGG) probiotics in radiation enteritis using in vivo mice. A total of 40 mice were randomly assigned to four groups: control, probiotics, radiotherapy (RT), and RT + probiotics. For the group of probiotics, 0.2 mL of solution that contained 1.0 × 108 colony-forming units (CFU) of LGG was used and orally administered daily until sacrifice. For RT, a single dose of 14 Gy was administered using a 6 mega-voltage photon beam to the abdominopelvic area. Mice were sacrifice at day 4 (S1) and day 7 (S2) after RT. Their jejunum, colon, and stool were collected. A multiplex cytokine assay and 16 s ribosomal RNA amplicon sequencing were then performed. Regarding cytokine concentrations in tissues, pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin-6 and monocyte chemotactic protein-1, showed significantly decreased protein levels in colon tissues of the RT + probiotics group than in the RT alone group (all p < 0.05). As for comparing microbial abundance through alpha-diversity and beta-diversity, no significant differences were observed between the RT + probiotics and RT alone groups, except for an increase in alpha-diversity in the stool of the RT + probiotics group. Upon analysis of differential microbes based on treatment, the dominance of anti-inflammatory-related microbes, such as Porphyromonadaceae, Bacteroides acidifaciens, and Ruminococcus, was observed in the jejunum, colon, and stool of the RT + probiotics group. With regard to predicted metabolic pathway abundances, the pathways associated with anti-inflammatory processes, such as biosynthesis of pyrimidine nucleotides, peptidoglycans, tryptophan, adenosylcobalamin, and propionate, were differentially identified in the RT + probiotics group compared to the RT alone group. Protective effects of probiotics on radiation enteritis were potentially derived from dominant anti-inflammation-related microbes and metabolites.

Radiation enteropathy-related depression: A neglectable course of disease by gut bacterial dysbiosis

Radiation enteropathy (RE) is common in patients treated with radiotherapy for pelvic-abdominal cancers. Accumulating data indicate that gut commensal bacteria determine intestinal radiosensitivity. Radiotherapy can result in gut bacterial dysbiosis. Gut bacterial dysbiosis contributes to the pathogenesis of RE. Mild to moderate depressive symptoms can be observed in patients with RE in clinical settings; however, the rate of these symptoms has not been reported. Studies have demonstrated that gut bacterial dysbiosis induces depression. In the state of comorbidity, RE and depression may be understood as local and abscopal manifestations of gut bacterial disorders. The ability of comorbid depression to worsen inflammatory bowel disease (IBD) has long been demonstrated and is associated with dysfunction of cholinergic neural anti-inflammatory pathways. There is a lack of direct evidence for RE comorbid with depression. It is widely accepted that RE shares similar pathophysiologic mechanisms with IBD. Therefore, we may be able to draw on the findings of the relationship between IBD and depression. This review will explore the relationship between gut bacteria, RE, and depression in light of the available evidence and indicate a method for investigating the mechanisms of RE combined with depression. We will also describe new developments in the treatment of RE with probiotics, prebiotics, and fecal microbial transplantation.

Radiation injury and gut microbiota-based treatment

The exposure to either medical sources or accidental radiation can cause varying degrees of radiation injury (RI). RI is a common disease involving multiple human body parts and organs, yet effective treatments are currently limited. Accumulating evidence suggests gut microbiota are closely associated with the development and prevention of various RI. This article summarizes 10 common types of RI and their possible mechanisms. It also highlights the changes and potential microbiota-based treatments for RI, including probiotics, metabolites, and microbiota transplantation. Additionally, a 5P-Framework is proposed to provide a comprehensive strategy for managing RI.

Role of microbiota in radiation-induced small-bowel damage

Radiation-induced gastrointestinal damage is a common acute radiation syndrome. Previous studies have highlighted that Galectin-1 and Interleukin-6 (IL-6) are associated with flaking of small intestinal villi and intestinal radioresistance. Therefore, our goal is to study whether gut bacteria regulated by galectin-1 or IL-6 can mitigate radiation-induced small intestine damage. In this study, differences between galectin-1, sgp130-regulated and wild-type (WT) mice were analyzed by microbiome array. The effects of the Firmicutes/Bacteroidetes (F/B) ratio and the proportion of bacterial distribution at the phylum level were observed after 18 Gy whole abdomen radiation. Fecal microbiota transplantation was used to implant radioresistant gut flora into WT mice, and the number of viable small intestinal crypt foci was observed by immunohistochemistry. Fecal transplantation from galectin-1 knockout and sgp130 transgenic mice, with higher radiation resistance, into WT mice significantly increased the number of surviving small intestinal crypts. This radiation resistance, generated through gene regulation, was not affected by the F/B ratio. We initially found that the small intestinal villi of WT mice receiving radioresistant mouse fecal bacteria demonstrated better repair outcomes after radiation exposure. These results indicate the need for a focus on the identification and application of superior radioresistant bacterial strains. In our laboratory, we will further investigate specific radioresistant bacterial strains to alleviate acute side effects of radiation therapy to improve the patients' immune ability and postoperative quality of life.

Perioperative or Postoperative Probiotics Reduce Treatment-Related Complications in Adult Colorectal Cancer Patients Undergoing Surgery: A Systematic Review and Meta-analysis

PURPOSE

This systematic review and meta-analysis of randomized controlled trials (RCTs) aimed to assess the efficacy of perioperative or postoperative probiotics as a therapeutic approach for managing colorectal cancer treatment-related complications in patients undergoing surgery, with or without adjuvant therapy.

METHODS

MEDLINE, Embase, and Scopus databases were searched.

RESULTS

Ten RCTs with 1276 patients were included. There was a significant decrease in the incidence of diarrhea (odds ratio (OR) 0.42; 95% CI 0.31 to 0.55; p < 0.001), surgical site infection (OR 0.44; 95% CI 0.22 to 0.89; p = 0.023), urinary infection (OR 0.43; 95% CI 0.20 to 0.91; p = 0.028), pulmonary infection (OR 0.30; 95% CI 0.15 to 0.60; p < 0.001), abdominal distention (OR 0.43; 95% CI 0.25 to 0.76; p = 0.004), length of ATB therapy (mean difference (MD) - 1.66 days; 95% CI - 2.13 to - 1.19 days; p < 0.001), and duration of postoperative pyrexia (MD - 0.80 days; 95% CI - 1.38 to - 0.22 days; p = 0.007) in the probiotic group. Nevertheless, length of hospital stay, time to first defecation, and time to first solid diet were not different between groups.

CONCLUSION

Our findings suggest that perioperative or postoperative probiotics is effective for reducing treatment-related complications in patients with colorectal cancer undergoing surgery, with a lower rate of adverse events.

Microbiota-derived I3A protects the intestine against radiation injury by activating AhR/IL-10/Wnt signaling and enhancing the abundance of probiotics

The intestine is prone to radiation damage in patients undergoing radiotherapy for pelvic tumors. However, there are currently no effective drugs available for the prevention or treatment of radiation-induced enteropathy (RIE). In this study, we aimed at investigating the impact of indole-3-carboxaldehyde (I3A) derived from the intestinal microbiota on RIE. Intestinal organoids were isolated and cultivated for screening radioprotective tryptophan metabolites. A RIE model was established using 13 Gy whole-abdominal irradiation in male C57BL/6J mice. After oral administration of I3A, its radioprotective ability was assessed through the observation of survival rates, clinical scores, and pathological analysis. Intestinal stem cell survival and changes in the intestinal barrier were observed through immunofluorescence and immunohistochemistry. Subsequently, the radioprotective mechanisms of I3A was investigated through 16S rRNA and transcriptome sequencing, respectively. Finally, human colon cancer cells and organoids were cultured to assess the influence of I3A on tumor radiotherapy. I3A exhibited the most potent radioprotective effect on intestinal organoids. Oral administration of I3A treatment significantly increased the survival rate in irradiated mice, improved clinical and histological scores, mitigated mucosal damage, enhanced the proliferation and differentiation of Lgr5+ intestinal stem cells, and maintained intestinal barrier integrity. Furthermore, I3A enhanced the abundance of probiotics, and activated the AhR/IL-10/Wnt signaling pathway to promote intestinal epithelial proliferation. As a crucial tryptophan metabolite, I3A promotes intestinal epithelial cell proliferation through the AhR/IL-10/Wnt signaling pathway and upregulates the abundance of probiotics to treat RIE. Microbiota-derived I3A demonstrates potential clinical application value for the treatment of RIE.

Effect of probiotic supplementation on chemotherapy- and radiotherapy-related diarrhoea in patients with cancer: an umbrella review of systematic reviews and meta-analyses

To date, several systematic reviews and meta-analyses (SRMA) have investigated the effects of probiotics, but the certainty of the evidence for an effect on chemotherapy and radiotherapy-related diarrhoea has not been assessed. We conducted an overview of SRMA, searching MEDLINE, Scopus, and ISI Web of Science from inception up to February 2022. We summarised the findings of eligible SRMA. Subsequently, we included randomised clinical trials (RCT) from the SRMA in meta-analyses, using a quality effects model to calculate the OR and 95 % CI for each outcome. We used ‘A Measurement Tool to Assess Systematic Reviews’ and the Cochrane risk of bias tool to assess the methodological quality of the SRMA and their RCT, respectively. We used the ‘Grading of Recommendations Assessment, Development, and Evaluation’.We included thirteen SRMA, which reported pooled effect sizes for chemotherapy and radiotherapy-related diarrhoea based on a total of eighteen RCT. Our meta-analyses demonstrated statistically significant beneficial effects from probiotics on all outcomes, except stool consistency; diarrhoea (any grade) OR 0·35 (95 % CI 0·22, 0·54), grade ≥ 2 diarrhoea 0·43 (0·25, 0·74), grade ≥ 3 diarrhoea 0·30 (0·15, 0·59), use of medication 0·49 (0·27, 0·88), soft stool 1·10 (0·44, 2·76) and watery stool 0·52 (0·29, 1·29). Probiotics use can reduce the incidence of diarrhoea in cancer patients in chemotherapy and radiotherapy, but the certainty of evidence for significant outcomes was very low and low.

Modulating the gut microbiota by probiotics, prebiotics, postbiotics, and fecal microbiota transplantation: An emerging trend in cancer patient care

Treatment resistance, together with acute and late adverse effects, represents critical issues in the management of cancer patients. Promising results from preclinical and clinical research underline the emerging trend of a microbiome-based approach in oncology. Favorable bacterial species and higher gut diversity are associated with increased treatment efficacy, mainly in chemo- and immunotherapy. On the other hand, alterations in the composition and activity of gut microbial communities are linked to intestinal dysbiosis and contribute to high treatment-induced toxicity. In this Review, we provide an overview of studies concerning gut microbiota modulation in patients with solid and hematologic malignancies with a focus on probiotics, prebiotics, postbiotics, and fecal microbiota transplantation. Targeting the gut microbiome might bring clinical benefits and improve patient outcomes. However, a deeper understanding of mechanisms and large clinical trials concerning microbiome and immunological profiling is warranted to identify safe and effective ways to incorporate microbiota-based interventions in routine clinical practice.

It Is All about Probiotics to Control Cervical Cancer

Cervical cancer (CC) is the fourth most common malignancy in female patients. "Human papillomavirus" (HPV) contamination is a leading cause of all forms of cervical cancer, accounting for an expected 570,000 reported incidents in 2018. Two HPV strains (16 and 18) are responsible for 70% of CC and pre-cancerous cervical abnormalities. CC is one of the foremost reasons for the malignancy death rate in India among women ranging from 30 to 69 years of age in India, responsible for 17% of all cancer deaths. Currently approved cervical cancer treatments are associated with adverse reactions that might harm the lives of women affected by this disease. Consequently, probiotics can play a vital role in the treatment of CC. It is reflected from various studies regarding the role of probiotics in the diagnosis, prevention or treatment of cancer. In this review article, we have discussed the rationale of probiotics for treatment of CC, the role of probiotics as effective adjuvants in anti-cancer therapy and the combined effect of the anti-cancer drug along with probiotics to minimize the side effects due to chemotherapy.

The role of bacteria and its derived biomaterials in cancer radiotherapy

Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics. It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors, especially when combined with traditional therapy, such as radiotherapy. According to their different biological characteristics, bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues. Moreover, genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy. In this review, we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years, expounding that the bacteria, bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment (TME) and immune effects. Furthermore, some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory, anti-oxidation and apoptosis inhibition. In conclusion, the prospect of bacteria in radiotherapy will be very extensive, but its biological safety and mechanism need to be further evaluated and studied.

Medication adjustment of afatinib and combination therapy with sitagliptin for alleviating afatinib-induced diarrhea in rats

Afatinib, as the first-line treatment for non-small cell lung cancer (NSCLC), causes severe gastrointestinal adverse reactions that greatly affect patients' quality of life and even potentially result in treatment discontinuation. Multiple dose adjustments and concomitant use of anti-diarrheal medications are commonly employed to manage diarrhea, also allowing for a recovery period between each adjustment. However, these approaches are based on empirical guidance and still have limitations. This study aims to explore reliable approaches to alleviate diarrhea by focusing on two strategies: adjusting the dosing regimen of afatinib itself and implementing combination therapy. In this study, we firstly revealed a dose-dependent relationship between afatinib-induced diarrhea and gastrointestinal epithelial damage, resulting in atrophy, reduced expression of tight junction proteins, and increased permeability. We further found that even after discontinuation of the medication, although the severity of diarrhea had improved to baseline, the tight junction proteins and permeability of the intestinal epithelium did not fully recover, and the pharmacokinetics studies showed that drug absorption significantly increased than normal. This indicated the recovery period was longer than expected and may accelerate the occurrence of subsequent episodes of diarrhea. Hence, it would be prudent to consider adjustments to the starting dose or the recovery interval. Furthermore, we initially investigated the relationship between DPP enzyme and afatinib-induced diarrhea and found a significant decrease in plasma DPP enzyme activity following afatinib-induced diarrhea. Subsequently, we conducted continuous treatment with sitagliptin and observed significant improvement in afatinib-induced diarrhea. We observed that sitagliptin can promote the production of anti-inflammatory factors, increase the expression of intestinal epithelial tight junction proteins, and improve intestinal microbiota, further validating the mechanism through the use of GLP-23-33 as GLP-2 receptor inhibitor. In conclusion, sitagliptin exhibits promising potential as a therapeutic option for managing afatinib-induced diarrhea. Taken together, our study provides valuable insights into alleviating afatinib-induced diarrhea through both afatinib medication adjustment and sitagliptin combination therapy.

Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications

In the past period, due to the rapid development of next-generation sequencing technology, accumulating evidence has clarified the complex role of the human microbiota in the development of cancer and the therapeutic response. More importantly, available evidence seems to indicate that modulating the composition of the gut microbiota to improve the efficacy of anti-cancer drugs may be feasible. However, intricate complexities exist, and a deep and comprehensive understanding of how the human microbiota interacts with cancer is critical to realize its full potential in cancer treatment. The purpose of this review is to summarize the initial clues on molecular mechanisms regarding the mutual effects between the gut microbiota and cancer development, and to highlight the relationship between gut microbes and the efficacy of immunotherapy, chemotherapy, radiation therapy and cancer surgery, which may provide insights into the formulation of individualized therapeutic strategies for cancer management. In addition, the current and emerging microbial interventions for cancer therapy as well as their clinical applications are summarized. Although many challenges remain for now, the great importance and full potential of the gut microbiota cannot be overstated for the development of individualized anti-cancer strategies, and it is necessary to explore a holistic approach that incorporates microbial modulation therapy in cancer.

Future Modulation of Gut Microbiota: From Eubiotics to FMT, Engineered Bacteria, and Phage Therapy

The human gut is inhabited by a multitude of bacteria, yeasts, and viruses. A dynamic balance among these microorganisms is associated with the well-being of the human being, and a large body of evidence supports a role of dysbiosis in the pathogenesis of several diseases. Given the importance of the gut microbiota in the preservation of human health, probiotics, prebiotics, synbiotics, and postbiotics have been classically used as strategies to modulate the gut microbiota and achieve beneficial effects for the host. Nonetheless, several molecules not typically included in these categories have demonstrated a role in restoring the equilibrium among the components of the gut microbiota. Among these, rifaximin, as well as other antimicrobial drugs, such as triclosan, or natural compounds (including evodiamine and polyphenols) have common pleiotropic characteristics. On one hand, they suppress the growth of dangerous bacteria while promoting beneficial bacteria in the gut microbiota. On the other hand, they contribute to the regulation of the immune response in the case of dysbiosis by directly influencing the immune system and epithelial cells or by inducing the gut bacteria to produce immune-modulatory compounds, such as short-chain fatty acids. Fecal microbiota transplantation (FMT) has also been investigated as a procedure to restore the equilibrium of the gut microbiota and has shown benefits in many diseases, including inflammatory bowel disease, chronic liver disorders, and extraintestinal autoimmune conditions. One of the most significant limits of the current techniques used to modulate the gut microbiota is the lack of tools that can precisely modulate specific members of complex microbial communities. Novel approaches, including the use of engineered probiotic bacteria or bacteriophage-based therapy, have recently appeared as promising strategies to provide targeted and tailored therapeutic modulation of the gut microbiota, but their role in clinical practice has yet to be clarified. The aim of this review is to discuss the most recently introduced innovations in the field of therapeutic microbiome modulation.

Pathogenesis and therapy of radiation enteritis with gut microbiota

Radiotherapy is widely used in clinic due to its good effect for cancer treatment. But radiotherapy of malignant tumors in the abdomen and pelvis is easy to cause radiation enteritis complications. Gastrointestinal tract contains numerous microbes, most of which are mutualistic relationship with the host. Abdominal radiation results in gut microbiota dysbiosis. Microbial therapy can directly target gut microbiota to reverse microbiota dysbiosis, hence relieving intestinal inflammation. In this review, we mainly summarized pathogenesis and novel therapy of the radiation-induced intestinal injury with gut microbiota dysbiosis and envision the opportunities and challenges of radiation enteritis therapy.

Role of Probiotics and Synbiotics in Preventing Chemoradiotherapy-Associated Toxicity in Colorectal Cancer Patients: A Systematic Review

Background

Previous studies found that the use of probiotics may have a protective effect on chemotherapy-associated toxicity in cancer patients. A systematic review was conducted to evaluate the effect of probiotics and synbiotics on chemoradiotherapy-associated toxicity in colorectal cancer (CRC) patients.

Methods

A systematic review of randomized controlled trials (RCTs) was performed to assess the effect of probiotics and synbiotics in CRC patients undergoing chemotherapy. All RCTs in English, up to January 2021, were included through a literature search in Scopus, Google Scholar, PubMed (PMC Central, MEDLINE), ClinicalTrials.gov, and ProQuest databases. The impact of probiotics and synbiotics on the side effects associated with chemotherapy, radiotherapy, and chemoradiotherapy in CRC patients was evaluated. The quality of the RTCs was independently assessed by two reviewers. EndNote X8 software was used to manage the search results.

Results

Of the 904 identified articles, three studies finally met the inclusion criteria and were systematically reviewed. Two studies reported that patients who received probiotics had less abdominal discomfort and required less bowel toxicity-related hospital care. Although probiotic supplementation lowered radiation-associated diarrhea, it had no significant effect when anti-diarrheal drugs were used. Another study reported that synbiotic supplementation improved quality of life and marginally reduced diarrhea and serum levels of high-sensitivity C-reactive protein (hs-CRP) and matrix metalloproteinase (MMP-2 and MMP-9).

Conclusion

Probiotics and synbiotics do not have a significant effect on reducing chemotherapy-associated toxicity and diarrhea in CRC patients. These findings should be substantiated by further RCTs with rigorous placebo-controlled studies.

Potential applications of drug delivery technologies against radiation enteritis

INTRODUCTION

The incidence of abdominal tumors, such as colorectal and prostate cancers, continually increases. Radiation therapy is widely applied in the clinical treatment of patients with abdominal/pelvic cancers, but it often unfortunately causes radiation enteritis (RE) involving the intestine, colon, and rectum. However, there is a lack of suitable treatment options for effective prevention and treatment of RE.

AREAS COVERED

Conventional clinical drugs for preventing and treating RE are usually applied by enemas and oral administration. Innovative gut-targeted drug delivery systems including hydrogels, microspheres, and nanoparticles are proposed to improve the prevention and curation of RE.

EXPERT OPINION

The prevention and treatment of RE have not attracted sufficient attention in the clinical practice, especially compared to the treatment of tumors, although RE takes patients great pains. Drug delivery to the pathological sites of RE is a huge challenge. The short retention and weak targeting of conventional drug delivery systems affect the therapeutic efficiency of anti-RE drugs. Novel drug delivery systems including hydrogels, microspheres, and nanoparticles can allow drugs long-term retention in the gut and targeting the inflammation sites to alleviate radiation-induced injury.

The Debate between the Human Microbiota and Immune System in Treating Aerodigestive and Digestive Tract Cancers: A Review

The human microbiota comprises a group of microorganisms co-existing in the human body. Unbalanced microbiota homeostasis may impact metabolic and immune system regulation, shrinking the edge between health and disease. Recently, the microbiota has been considered a prominent extrinsic/intrinsic element of cancer development and a promising milestone in the modulation of conventional cancer treatments. Particularly, the oral cavity represents a yin-and-yang target site for microorganisms that can promote human health or contribute to oral cancer development, such as Fusobacterium nucleatum. Moreover, Helicobacter pylori has also been implicated in esophageal and stomach cancers, and decreased butyrate-producing bacteria, such as Lachnospiraceae spp. and Ruminococcaceae, have demonstrated a protective role in the development of colorectal cancer. Interestingly, prebiotics, e.g., polyphenols, probiotics (Faecalibacterium, Bifidobacterium, Lactobacillus, and Burkholderia), postbiotics (inosine, butyrate, and propionate), and innovative nanomedicines can modulate antitumor immunity, circumventing resistance to conventional treatments and could complement existing therapies. Therefore, this manuscript delivers a holistic perspective on the interaction between human microbiota and cancer development and treatment, particularly in aerodigestive and digestive cancers, focusing on applying prebiotics, probiotics, and nanomedicines to overcome some challenges in treating cancer.

Exploiting the Acidic Extracellular pH: Evaluation of Streptococcus salivarius M18 Postbiotics to Target Cancer Cells

Previously, we showed that the growth, antibiotic resistance, and biofilm formation properties of the pathogens Pseudomonas aeruginosa and Klebsiella pneumonia were tremendously inhibited by the cell-free supernatant of the oral probiotic Streptococcus salivarius M18. These anti-pathogenic activities of the supernatant were more efficient under acidic conditions. The present approach takes advantage of the acidic nature of the tumor microenvironment to evaluate the effect of the S. salivarius M18 postbiotics on colon cancer cells. In both two-dimensional (2D) and three-dimensional (3D) cell culture models, S. salivarius M18 cell-free supernatant showed anti-cancer actions in the pH conditions mimicking the acidity of the tumor. The inhibitory effect was more prominent when the colon cancer cells have been treated with the cell-free supernatant obtained from the inulin incubated S. salivarius M18. The results of this study point out the potential of the S. salivarius M18 functional probiotic products to be used for targeting low pH environments including the unique acidic microenvironment of tumors.

Exploiting dietary fibre and the gut microbiota in pelvic radiotherapy patients

With an ageing population, there is an urgent need to find alternatives to current standard-of-care chemoradiation schedules in the treatment of pelvic malignancies. The gut microbiota may be exploitable, having shown a valuable role in improving patient outcomes in anticancer immunotherapy. These bacteria feed on dietary fibres, which reach the large intestine intact, resulting in the production of beneficial metabolites, including short-chain fatty acids. The gut microbiota can impact radiotherapy (RT) treatment responses and itself be altered by the radiation. Evidence is emerging that manipulation of the gut microbiota by dietary fibre supplementation can improve tumour responses and reduce normal tissue side effects following RT, although data on tumour response are limited to date. Both may be mediated by immune and non-immune effects of gut microbiota and their metabolites. Alternative approaches include use of probiotics and faecal microbiota transplantation (FMT). Current evidence will be reviewed regarding the use of dietary fibre interventions and gut microbiota modification in improving outcomes for pelvic RT patients. However, data regarding baseline (pre-RT) gut microbiota of RT patients and timing of dietary fibre manipulation (before or during RT) is limited, heterogenous and inconclusive, thus more robust clinical studies are required before these strategies can be applied clinically.

Targeting the gut microbiota for cancer therapy

Growing evidence suggests that the gut microbiota modulates the efficacy and toxicity of cancer therapy, most notably immunotherapy and its immune-related adverse effects. The poor response to immunotherapy in patients treated with antibiotics supports this influential role of the microbiota. Until recently, results pertaining to the identification of the microbial species responsible for these effects were incongruent, and relatively few studies analysed the underlying mechanisms. A better understanding of the taxonomy of the species involved and of the mechanisms of action has since been achieved. Defined bacterial species have been shown to promote an improved response to immune-checkpoint inhibitors by producing different products or metabolites. However, a suppressive effect of Gram-negative bacteria may be dominant in some unresponsive patients. Machine learning approaches trained on the microbiota composition of patients can predict the ability of patients to respond to immunotherapy with some accuracy. Thus, interest in modulating the microbiota composition to improve patient responsiveness to therapy has been mounting. Clinical proof-of-concept studies have demonstrated that faecal microbiota transplantation or dietary interventions might be utilized clinically to improve the success rate of immunotherapy in patients with cancer. Here, we review recent advances and discuss emerging strategies for microbiota-based cancer therapies.

Preventive Effect of Probiotics on Oral Mucositis Induced by Cancer Treatment: A Systematic Review and Meta-Analysis

Oral mucositis is a common adverse effect of cancer therapy. Probiotics have been shown to exert anti-inflammatory and immunomodulatory effects. We performed a meta-analysis of randomized controlled trials (RCTs) to investigate whether probiotics can prevent cancer therapy−induced oral mucositis. We searched PubMed, Embase, Cochrane Library, and ClinicalTrials.gov databases for trials related to probiotics and oral mucositis published before September 2022; no language restrictions were applied. The primary outcome was the incidence of oral mucositis and severe oral mucositis. Secondary outcomes were the requirement for enteral nutrition during treatment, body weight loss, and decreased quality of life. The study has been registered in PROSPERO (number: CRD 42022302339). Eight RCTs, including 708 patients, were reviewed; however, a meta-analysis of only seven trials could be performed. Three trials using Lactobacilli-based probiotics reported that the incidence of oral mucositis in the probiotic group was significantly low (risk ratio [RR] = 0.84, 95% confidence interval [CI] = 0.77−0.93, p = 0.0004). Seven trials reported a significantly low incidence of severe oral mucositis in the probiotic group (RR = 0.65, 95% CI = 0.53−0.81, p < 0.0001). The requirement of enteral nutrition was significantly low in the probiotic group (odds ratio = 0.34, 95% CI: 0.13−0.92, p < 0.05). This study demonstrated the effectiveness of probiotics in the prevention and mitigation of cancer therapy−induced oral mucositis. We recommend the use of probiotics to prevent and treat oral mucositis during cancer therapy.

Effects of probiotic supplementation on related side effects after chemoradiotherapy in cancer patients

OBJECTIVES

Chemotherapy and radiotherapy generally cause serious adverse side effects in cancer patients, thereby affecting subsequent treatment. Numerous studies have shown that taking probiotics is an option for preventing and treating these side effects. In this investigation, a meta-analysis of the effects of oral probiotics on side effects brought on by radiotherapy, chemotherapy, or chemoradiotherapy treatment will be carried out.

METHODS

Two researchers independently and carefully reviewed all pertinent studies that were published before June 30, 2022 and were accessible on PubMed, Embase, Cochrane Library, and the Web of Science. Moreover, the Cochrane Collaboration's Tool was used to evaluate the risk of bias. Utilizing Review Manager software version 5.4, data were retrieved from eligible studies to evaluate their merits and determine odds ratios (OR) and 95% confidence intervals (CIs) (RevMan 5.4).

RESULTS

2 097 patients from 16 randomized controlled trials were extracted, and standard meta-analysis methods were used to examine the data. Compared with the placebo groups, oral probiotics significantly reduced the side effects caused by radiotherapy and chemotherapy on various types of cancer, such as head and neck cancer, pelvic and abdominal cancer, breast cancer, lung cancer, etc. (OR: 0.31, 95% CI: 0.20 - 0.48; P < 0.005). Further analysis found that the incidence of diarrhea in patients with pelvic and abdominal cancers (OR: 0.32, 95% CI: 0.16 - 0.65; P < 0.005) and the frequency of oral mucositis in patients with head and neck tumors were also significantly lower (OR: 0.28, 95% CI: 0.18 - 0.43; P < 0.005) after the oral administration of probiotics. This suggests that probiotics have a positive influence on the treatment of side effects after chemoradiotherapy. Additionally, a funnel plot revealed that there was no significant publication bias in this study.

CONCLUSIONS

Probiotics may help to reduce the occurrence of cancer therapy-related side effects, especially oral mucositis in head and neck tumors and diarrhea in patients with pelvic and abdominal tumors. However, given the small number of clinical trials involved, additional randomized, double-blind, multicentric trials in a larger population are required. This paper may assist researchers in improving trial design in the selection of probiotic strains and selecting appropriate patients who may benefit from probiotic treatments.

Decreasing the Adverse Effects in Pelvic Radiation Therapy: A Randomized Controlled Trial Evaluating the Use of Probiotics

PURPOSE

The aim of this randomized controlled trial was to evaluate the potential benefit from 2 probiotic bacteria of the species Lactiplantibacillus plantarum against radiation therapy-induced comorbidities.

METHODS AND MATERIALS

Women (>18 years of age) scheduled for radiation therapy because of gynecologic cancer were randomly allocated to consume placebo or either low-dose probiotics (1 × 10¹⁰ colony-forming unit/capsule twice daily) or high-dose probiotics (5 × 10¹⁰ colony-forming unit/capsule twice daily). The intervention started approximately 1 week before the onset of radiation therapy and continued until 2 weeks after completion. During this period the participants were daily filling in a study diary documenting the incidence and severity of symptoms, intake of concomitant medication, and stool consistency. The primary endpoint was the probiotic effect on the mean number of loose stools during radiation therapy.

RESULTS

Of the 97 randomized women, 75 provided data for the analysis of the results. The mean number of loose stools (sum of Bristol stool type 6 and 7) was not significantly reduced in the probiotic groups, but there was a significant reduction in the mean number of days with >1 loose stool with 15.04 ± 8.92 days in the placebo and 8.65 ± 5.93 days in the high-dose probiotics group (P = .014). The benefit was even more pronounced in the 2 weeks following the end of radiation therapy (P = .005). Moreover, intake of the probiotics resulted in a reduced severity of the symptoms grinding abdominal pain (P = .041) and defecation urgency (P = .08) and a reduced percentage of days with these symptoms (P = .023 and P = .042, respectively), compared with placebo. There were no differences regarding reported adverse events.

CONCLUSIONS

Intake of the 2 probiotic bacteria was beneficial and reduced many measures or symptoms of the radiation-induced toxicity in women treated for gynecologic cancer.

The role of probiotics in vaginal health

Probiotics have been widely used in the treatment of intestinal diseases, but the effect of probiotics on female reproductive tract health is still controversial. Lactobacillus is the most abundant microorganism in the vagina, which is related to the vaginal mucosal barrier. Lactobacillus adheres to the vaginal epithelium and can competitively antagonize the colonization of pathogens. The factors produced by Lactobacillus, such as bacteriocin and hydrogen peroxide (H₂O₂), can inhibit the growth of pathogenic microorganisms and maintain the low pH environment of the vagina. Probiotics play an important role in maintaining the stability of vaginal microenvironment, improving immune defense and blocking the progression of cervical cancer. We review the research progress of probiotics represented by Lactobacillus in gynecological diseases such as human papilloma virus (HPV) infection, bacterial vaginosis (BV) and Genitourinary Syndrome of Menopause (GSM), so as to provide basis for further exerting the role of probiotics in women’s health.

The gut microbiome and melanoma: A review

Disturbances in the microbial ecosystem have been implemented in chronic inflammation, immune evasion and carcinogenesis, with certain microbes associated with the development of specific cancers. In recent times, the gut microbiome has been recognised as a potential novel player in the pathogenesis and treatment of malignant melanoma. It has been shown that the composition of gut microbiota in early-stage melanoma changes from in situ to invasive and then to metastatic disease. The gut bacterial and fungal profile has also been found to be significantly different in melanoma patients compared to controls. Multiple studies of immune checkpoint inhibitor (ICI) therapies have shown that the commensal microbiota may have an impact on anti-tumor immunity and therefore ICI response in cancer patients. When it comes to chemotherapy and radiotherapy treatments, studies demonstrate that gut microbiota are invaluable in the repair of radiation and chemotherapy-induced damage and therapeutic manipulation of gut microbiota can be an effective strategy to deal with side effects. Studies demonstrate the oncogenic and tumor-suppressive properties of the gut microbiome, which may play a role in the pathogenesis of melanoma. Despite this, investigations into specific interactions are still in its infancy, but starting to gain momentum as more significant and clinically relevant effects are emerging.

Influence of Probiotics in Prevention and Treatment of Patients Who Undergo Chemotherapy or/and Radiotherapy and Suffer from Mucositis, Diarrhoea, Constipation, Nausea and Vomiting

The administration of probiotics to patients treated with chemo- and/or radiotherapy is assumed to be beneficial. The aim of this study was to evaluate the effects of probiotic intake on the severity of selected gastrointestinal side effects of chemotherapy and radiotherapy. The searched databases included PubMed, Web of Science, and Scopus from which twenty-one studies were included. Most of them concerned diarrhoea, however, two of the studies examined constipation, another two nausea and vomiting, and eight of the included studies regarded mucositis. The total number of patients equalled 2621. The time of the conducted therapy, the administered species, neoplasm pathology, and adjuvant therapy varied. The outcome was assessed by gathering information about the statistical significance of the improvements. An enhancement was observed in thirteen studies, where probiotics had a significant impact on each of the included chemo- and/or radiotherapy side effects. However, the heterogeneity of the assessed data makes it impossible to state a firm conclusion.

Effects of Probiotics at the Interface of Metabolism and Immunity to Prevent Colorectal Cancer-Associated Gut Inflammation: A Systematic Network and Meta-Analysis With Molecular Docking Studies

Background

Dysbiosis/imbalance in the gut microbial composition triggers chronic inflammation and promotes colorectal cancer (CRC). Modulation of the gut microbiome by the administration of probiotics is a promising strategy to reduce carcinogenic inflammation. However, the mechanism remains unclear.

Methods

In this study, we presented a systematic network, meta-analysis, and molecular docking studies to determine the plausible mechanism of probiotic intervention in diminishing CRC-causing inflammations.

Results

We selected 77 clinical, preclinical, in vitro, and in vivo articles (PRISMA guidelines) and identified 36 probiotics and 135 training genes connected to patients with CRC with probiotic application. The meta-analysis rationalizes the application of probiotics in the prevention and treatment of CRC. An association network is generated with 540 nodes and 1,423 edges. MCODE cluster analysis identifies 43 densely interconnected modules from the network. Gene ontology (GO) and pathway enrichment analysis of the top scoring and functionally significant modules reveal stress-induced metabolic pathways (JNK, MAPK), immunomodulatory pathways, intrinsic apoptotic pathways, and autophagy as contributors for CRC where probiotics could offer major benefits. Based on the enrichment analyses, 23 CRC-associated proteins and 7 probiotic-derived bacteriocins were selected for molecular docking studies. Results indicate that the key CRC-associated proteins (e.g., COX-2, CASP9, PI3K, and IL18R) significantly interact with the probiotic-derived bacteriocins (e.g., plantaricin JLA-9, lactococcin A, and lactococcin mmfii). Finally, a model for probiotic intervention to reduce CRC-associated inflammation has been proposed.

Conclusion

Probiotics and/or probiotic-derived bacteriocins could directly interact with CRC-promoting COX2. They could modulate inflammatory NLRP3 and NFkB pathways to reduce CRC-associated inflammation. Probiotics could also activate autophagy and apoptosis by regulating PI3K/AKT and caspase pathways in CRC. In summary, the potential mechanisms of probiotic-mediated CRC prevention include multiple signaling cascades, yet pathways related to metabolism and immunity are the crucial ones.

The Potential of the Gut Microbiome to Reshape the Cancer Therapy Paradigm: A Review

Importance

The gut microbiome, home to the vast kingdom of diverse commensal bacteria and other microorganisms residing within the gut, was once thought to only have roles primarily centered on digestive functions. However, recent advances in sequencing technology have elucidated intricate roles of the gut microbiome in cancer development and efficacy of therapeutic response that need to be comprehensively addressed from a clinically translational angle.

Observations

This review aims to highlight the current understanding of the association of the gut microbiome with the therapeutic response to immunotherapy, chemotherapy, radiotherapy, cancer surgery, and more, while also contextualizing possible synergistic strategies with the microbiome for tackling some of the most challenging tumors. It also provides insights on contemporary methods that target the microbiota and the current progression of findings being translated from bench to bedside.

Conclusions and Relevance

Ultimately, the importance of gut bacteria in cancer therapy cannot be overstated in its potential for ushering in a new era of cancer treatments. With the understanding that the microbiome may play critical roles in the tumor microenvironment, holistic approaches that integrate microbiome-modulating treatments with biological, immune, cell-based, and surgical cancer therapies should be explored.

The microbiome and precision oncology: an emerging paradigm in anticancer therapy

Understanding the host-microbiome interactions has emerged as an essential factor in improving human health and disease. Recent advances in understanding the intimate relationship of microbes with the host have uncovered various previously unknown underlying causes of disease development, progression, and treatment failure. The dynamic behaviour of the microbiome confers the heterogeneity in treatment response by modulating the immune response and inflammation in various diseases, including cancer. The growing insights into the microbial modulation of cancer through immunoregulation, xenometabolism, and increase in toxicity open a new era of personalised medicine. In the current review, we discuss the essential roles played by the microbiome in modulating the efficacy and toxicity of anticancer therapies (immunotherapy, chemotherapy, and radiotherapy). We also outline the current state of personalised medicine in the context of cancer and microbiome modulation. The knowledge about the role of cancer-microbiome communication will lead to designing other precise microbial modulation strategies for cancer treatment through enhanced efficacy and decreased toxicity.

Human Gut Microbiota in Health and Selected Cancers

The majority of the epithelial surfaces of our body, and the digestive tract, respiratory and urogenital systems, are colonized by a vast number of bacteria, archaea, fungi, protozoans, and viruses. These microbiota, particularly those of the intestines, play an important, beneficial role in digestion, metabolism, and the synthesis of vitamins. Their metabolites stimulate cytokine production by the human host, which are used against potential pathogens. The composition of the microbiota is influenced by several internal and external factors, including diet, age, disease, and lifestyle. Such changes, called dysbiosis, may be involved in the development of various conditions, such as metabolic diseases, including metabolic syndrome, type 2 diabetes mellitus, Hashimoto's thyroidis and Graves' disease; they can also play a role in nervous system disturbances, such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and depression. An association has also been found between gut microbiota dysbiosis and cancer. Our health is closely associated with the state of our microbiota, and their homeostasis. The aim of this review is to describe the associations between human gut microbiota and cancer, and examine the potential role of gut microbiota in anticancer therapy.

Oral microbiota transplantation fights against head and neck radiotherapy-induced oral mucositis in mice

Oral mucositis is a common radiotherapy-induced complication among nasal, oral and laryngeal cancer (NOALC) patients. This complication leads to decreased quality of life and has few treatments. Here, fractionated radiation was performed to mimic radiotherapy for NOALCs in mouse models. Oral microbiota transplantation (OMT) mitigated oral mucositis, as judged by reconstructed epithelium and tongue papillae, fewer infiltrated leukocytes and more proliferative cells in the oral epithelium. The gut microbiota impacted oral mucositis progression, and OMT restructured oral and gut bacteria configurations and reprogrammed the gene expression profile of tongue tissues. In vivo silencing of glossal S100 calcium binding protein A9 debilitated the radioprotection of OMT. In light of clinical samples, we identified that patients with different alteration trends of Lactobacillaceae frequency presented different primary lesions and prognoses of NOALC following radiotherapy. Together, our findings provide new insights into the oral-gut microbiota axis and underpin the suggestion that OMT might be harnessed as a novel remedy to fight against oral mucositis in NOALC patients following radiotherapy in preclinical settings. Of note, oral microorganisms, such as Lactobacillaceae, might be employed as biomarkers to predict the prognosis of NOALC with radiotherapy.

The effect of probiotics supplementation in postoperative cancer patients: a prospective pilot study

Purpose

Microbiota manipulation through selected probiotics may be a promising tool to prevent cancer development as well as onset, to improve clinical efficacy for cancer treatments. The purpose of this study was to evaluate change in microbiota composition after-probiotics supplementation and assessed the efficacy of probiotics in improving quality of life (QOL) in postoperative cancer patients.

Methods

Stool samples were collected from 30 cancer patients from February to October 2020 before (group I) and after (group II) 8 weeks of probiotics supplementation. We performed 16S ribosomal RNA gene sequencing to evaluate differences in gut microbiota between groups by comparing gut microbiota diversity, overall composition, and taxonomic signature abundance. The health-related QOL was evaluated through the EORTC Quality of life Questionnaire Core 30 questionnaire.

Results

Statistically significant differences were noted in group II; increase of Shannon and Simpson index (P = 0.004 and P = 0.001), decrease of Bacteroidetes and Fusobacteria at the phylum level (P = 0.032 and P = 0.014, retrospectively), increased of beneficial bacteria such as Weissella (0.096% vs. 0.361%, P < 0.004), Lactococcus (0.023% vs. 0.16%, P < 0.001), and Catenibacterium (0.0% vs. 0.005%, P < 0.042) at the genus level. There was a significant improvement in sleep disturbance (P = 0.039) in group II.

Conclusion

Gut microbiota in cancer patients can be manipulated by specific probiotic strains, result in an altered microbiota. Microbiota modulation by probiotics can be considered as part of a supplement that helps to increase gut microbiota diversity and improve QOL in cancer patients after surgery.

Prevention of radiotherapy induced enteropathy by probiotics (PREP): protocol for a double-blind randomized placebo-controlled trial

BACKGROUND

Radiation induced enteropathy is a common complication of radiotherapy for pelvic tumors and adversely affects patient quality of life. Probiotics are thought to restore bowel microflora to optimal levels and reinforce intestinal barrier capacity. Although probiotics are effective in the treatment of radiation induced enteropathy, less is known about their efficacy to prevent radiation induced enteropathy.

METHODS

This double-blind randomized placebo-controlled study will investigate the efficacy of probiotics to prevent radiation-induced enteropathy in patients with gynecologic or urologic cancer who received pelvic radiotherapy. The study is designed to enroll 248 eligible patients, who will be randomized 1:1 to a probiotic or placebo group. Toxicities will be evaluated using Common Terminology Criteria for Adverse Events (CTCAE) v5.0.

DISCUSSION

The primary aim of this study is to provide high level evidence for the ability of probiotics to prevent acute radiation induced enteropathy. The secondary aims are to determine the effects of probiotics on the incidence of chronic radiation induced enteropathy and the safety of probiotics in patients with gynecologic or urologic cancer.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT03978949 , Registered on 7 June 2019).

Gut Microbiota Modulation in the Context of Immune-Related Aspects of Lactobacillus spp. and Bifidobacterium spp. in Gastrointestinal Cancers

Accumulating evidence has revealed the critical roles of commensal microbes in cancer progression and recently several investigators have evaluated the therapeutic effectiveness of targeting the microbiota. This gut microbiota-related approach is especially attractive in the treatment of gastrointestinal cancers. Probiotics supplementation is a microbiota-targeted strategy that appears to improve treatment efficacy; Lactobacillus spp. and Bifidobacterium spp. are among the most commonly used probiotic agents. These bacteria seem to exert immunomodulatory effects, impacting on the immune system both locally and systemically. The gut microbiota are able to affect the efficiency of immunotherapy, mainly acting as inhibitors at immune checkpoints. The effects of immunotherapy may be modulated using traditional probiotic strains and/or next generation probiotics, such as Akkermansia municiphila. It is possible that probiotics might enhance the efficiency of immunotherapy based on PD-1/PD-L1 and CTLA-4 but more data are needed to confirm this speculation. Indeed, although there is experimental evidence for the efficacy of several strains, the health-promoting effects of numerous probiotics have not been demonstrated in human patients and furthermore the potential risks of these products, particularly in oncologic patients, are rarely mentioned.

Amelioration of 5-fluorouracil-induced intestinal mucositis by Streptococcus thermophilus ST4 in a mouse model

Intestinal mucositis is a commonly encountered toxic side effect in patients undergoing 5-fluorouracil (5-FU)-based chemotherapy. Numerous studies have shown that probiotics enable improving chemotherapy-induced intestinal mucositis, but the beneficial effects of probiotics differ depending on the strain. Therefore, in the present studies we suggest that S. thermophilus ST4 separated from raw milk may assess mucoprotective activity in 5-FU-induced intestinal mucositis. In our causal-comparative study design, fifteen mice were randomized assigned into three groups (n = 5/each group): control group, 5-FU group and 5-FU+S. thermophilus ST4 group. The control group was orally administrated saline only, and the 5-FU group was followed by intraperitoneal injection of 5-FU for 3 days after 10-day saline administration, and the 5-FU+S. thermophilus ST4 group was intragastrically subjected for S. thermophilus ST4 once per day during the whole experiment, starting from the first day of the experiment, followed by 5-FU intraperitoneal injection for 3 days after 10-day S. thermophilus ST4 pretreatment. Diarrhea score, pro-inflammatory cytokines serum levels, intestinal histopathology and short chain fatty acid were assessed. Here, we demonstrated the beneficial effects of S. thermophilus ST4 derived from raw milk against 5-FU-induced intestinal mucositis, including body weight reduction, appetite loss and diarrhea. Intrinsically, S. thermophilus ST4 effectively maintained epithelium structure in small intestines and colons as well as reduced the intestinal inflammation. Besides, S. thermophilus ST4 significantly increased the expression of acetic acid, reinforcing the muco-protective effects. In conclusion, our results demonstrate that S. thermophilus ST4 supplementation ameliorates 5-FU-induced intestinal mucositis. This suggests probiotic may serve as an alternative therapeutic strategy for the prevention or management of 5-FU-induced mucositis in the future.

Gut and Endometrial Microbiome Dysbiosis: A New Emergent Risk Factor for Endometrial Cancer

Endometrial cancer is one of the most common gynaecological malignancies worldwide. Histologically, two types of endometrial cancer with morphological and molecular differences and also therapeutic implications have been identified. Type I endometrial cancer has an endometrioid morphology and is estrogen-dependent, while Type II appears with non-endometrioid differentiation and follows an estrogen-unrelated pathway. Understanding the molecular biology and genetics of endometrial cancer is crucial for its prognosis and the development of novel therapies for its treatment. However, until now, scant attention has been paid to environmental components like the microbiome. Recently, due to emerging evidence that the uterus is not a sterile cavity, some studies have begun to investigate the composition of the endometrial microbiome and its role in endometrial cancer. In this review, we summarize the current state of this line of investigation, focusing on the relationship between gut and endometrial microbiome and inflammation, estrogen metabolism, and different endometrial cancer therapies.

The role of dietary supplements, including biotics, glutamine, polyunsaturated fatty acids and polyphenols, in reducing gastrointestinal side effects in patients undergoing pelvic radiotherapy: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Pelvic radiotherapy (RT) often results in gastrointestinal toxicity and clinical trials have demonstrated a potential benefit of dietary supplements in alleviating acute effects. However, no prophylactic agents have been approved to date for relief of gastrointestinal side-effects caused by pelvic radiation. In this systematic review, we evaluated the efficacy of dietary supplements in preventing or alleviating symptoms of gastrointestinal toxicity in patients undergoing pelvic RT.

MATERIALS AND METHODS

CENTRAL, MEDLINE, EMBASE, and ClinicalTrials.gov were searched up to June 2020 for randomised controlled trials. Interventions included four supplement categories: biotics, glutamine, poly-unsaturated fatty acids and polyphenols. Efficacy was determined with reference to outcomes based on symptoms of acute gastrointestinal toxicity, including diarrhoea, nausea, vomiting, flatulence/bloating, bowel movement frequency, tenesmus and rectal bleeding.

RESULTS

Twenty-three randomised controlled trials (1919 patients) were identified in this review. Compared with placebo, probiotics (RR = 0.71; 95% CI: 0.52 to 0.99), synbiotics (RR = 0.45; 95% CI: 0.28 to 0.73) and polyphenols (RR = 0.30; 95% CI: 0.13 to 0.70) were significantly associated with a lower risk of diarrhoea. Biotic supplements also reduced the risk of moderate to severe diarrhoea (RR = 0.49; 95% CI: 0.36 to 0.67) and the need for anti-diarrhoeal medication (RR = 0.64; 95%CI: 0.44 to 0.92). In contrast, glutamine had no effect on acute symptoms (RR = 1.05; 95% CI: 0.86 to 1.29). There was a non-significant trend for reduction in nausea and mean bowel movements per day using dietary supplements.

CONCLUSIONS

Biotic supplements, especially probiotics and synbiotics, reduce acute symptoms of gastrointestinal toxicity in patients undergoing pelvic radiotherapy.

Intestinal mucositis precedes dysbiosis in a mouse model for pelvic irradiation

Pelvic radiotherapy is known to evoke intestinal mucositis and dysbiosis. Currently, there are no effective therapies available to mitigate these injuries, which is partly due to a lack of insight into the events causing mucositis and dysbiosis. Here, the complex interplay between the murine host and its microbiome following pelvic irradiation was mapped by characterizing intestinal mucositis along with extensive 16S microbial profiling. We demonstrated important morphological and inflammatory implications within one day after exposure, thereby impairing intestinal functionality and inducing translocation of intraluminal bacteria into mesenteric lymph nodes as innovatively quantified by flow cytometry. Concurrent 16S microbial profiling revealed a delayed impact of pelvic irradiation on beta diversity. Analysis of composition of microbiomes identified biomarkers for pelvic irradiation. Among them, members of the families Ruminococcaceae, Lachnospiraceae and Porphyromonadaceae were differentially affected. Altogether, our unprecedented findings showed how pelvic irradiation evoked structural and functional changes in the intestine, which secondarily resulted in a microbiome shift. Therefore, the presented in vivo irradiation-gut-microbiome platform allows further research into the pathobiology of pelvic irradiation-induced intestinal mucositis and resultant dysbiosis, as well as the exploration of mitigating treatments including drugs and food supplements.

Probiotic Supplements on Oncology Patients' Treatment-Related Side Effects: A Systematic Review of Randomized Controlled Trials

Cancer affects more than 19.3 million people and has become the second leading cause of death worldwide. Chemo- and radiotherapy, the most common procedures in these patients, often produce unpleasant treatment-related side effects that have a direct impact on the quality of life of these patients. However, innovative therapeutic strategies such as probiotics are being implemented to manage these complications. Thus, this study aimed to evaluate the efficacy of probiotics supplements as a therapeutic strategy in adult oncology treatment-related side effects. A systematic review of randomized controlled trials was conducted in PubMed, Scielo, ProQuest and OVID databases up to and including January 2021, following the PRISMA guidelines. The quality of the included studies was assessed by the Jadad Scale. Twenty clinical trials published between 1988 and 2020 were included in this review. Seventeen studies (85%) revealed predominantly positive results when using probiotics to reduce the incidence of treatment-related side effects in oncology patients, while three studies (15%) reported no impact in their findings. This study sheds some light on the significance of chemotherapy and radiotherapy in altering the composition of gut microbiota, where probiotic strains may play an important role in preventing or mitigating treatment-related side effects.

Management of Long-Term Toxicity From Pelvic Radiation Therapy

Pelvic radiation therapy is an integral component in the treatment of various gastrointestinal, gynecologic, and genitourinary cancers. As survival rates from these malignancies improve, the prevalence of toxicity secondary to pelvic radiation has increased. Gastrointestinal toxicities are the most common complications and greatly impact quality of life. Toxicities can present in acute or late stages; although symptoms may be similar during both, the management may differ. Acute toxicities represent an inflammatory reaction in response to the radiation exposure, whereas late toxicities may arise as a result of small vessel disease, ischemia, and fibrosis. Currently, there are no large clinical trials and only limited guidelines on the management of late gastrointestinal radiation toxicities. Therapy is generally approached in a stepwise manner from medical to endoscopic to surgical methods. Several endoscopic therapies, such as the treatment of radiation proctitis with argon plasma coagulation and dilation of radiation bowel strictures, may prevent the need for surgical intervention, which may be associated with high morbidity and mortality. Given that late toxicities can occur years after radiation therapy, they are often difficult to recognize and diagnose. Successful management of late toxicities requires recognition, an understanding of the underlying pathophysiology, and a multidisciplinary approach. More dedicated research could clarify the prevalence of gastrointestinal pelvic radiation toxicities, permit a better understanding of the efficacy and safety profile of current therapies, and allow for the development of novel therapeutic approaches.

Role of Probiotics in Modulating Human Gut Microbiota Populations and Activities in Patients with Colorectal Cancer-A Systematic Review of Clinical Trials

BACKGROUND

Growing attention has been given to the role of nutrition and alterations of microbial diversity of the gut microbiota in colorectal cancer (CRC) pathogenesis. It has been suggested that probiotics and synbiotics modulate enteric microbiota and therefore may be used as an intervention to reduce the risk of CRC. The aim of this study was to evaluate the influence of probiotics/synbiotics administration on gut microbiota in patients with CRC.

METHODS

PubMed, Scopus, and Web of Science were searched between December 2020 and January 2021. Randomized controlled trials (RCTs) recruiting adults with CRC, who have taken probiotics/synbiotics for at least 6 days were included. Changes in gut microbiota and selected biochemical and inflammatory parameters (i.e., hsCRP, IL-2, hemoglobin) were retrieved.

RESULTS

The search resulted in 198 original research articles and a final 6 were selected as being eligible, including 457 subjects. The median age of patients was 65.4 years old and they were characterized by the median BMI value: 23.8 kg/m². The literature search revealed that probiotic/synbiotic administration improved enteric microbiota by increasing the abundance of beneficial bacteria such as Lactobacillus, Eubacterium, Peptostreptococcus, Bacillus and Bifidobacterium, and decreased the abundance of potentially harmful bacteria such as Fusobacterium, Porhyromonas, Pseudomonas and Enterococcus. Additionally, probiotic/synbiotic intervention improved release of antimicrobials, intestinal permeability, tight junction function in CRC patients.

CONCLUSIONS

The use of probiotics/synbiotics positively modulates enteric microbiota, improves postoperative outcomes, gut barrier function and reduces inflammatory parameters in patients suffering from CRC.

Radiotherapy-Specific Chronic Pain Syndromes in the Cancer Population: An Evidence-Based Narrative Review

While radiation therapy is increasingly utilized in the treatment paradigm of many solid cancers, the chronic effects of radiation therapies are poorly characterized. Notably, understanding radiation-specific chronic pain syndromes is paramount given that the diagnosis and management of these conditions can serve to prevent long-standing functional impairments, optimize quality of life, and even allow for continued radiotherapy candidacy. These radiation-specific chronic pain phenomena include dermatitis, mucositis, enteritis, connective tissue fibrosis, lymphedema, and neuropathic pain syndromes. It is necessary to maintain a low threshold of suspicion for appropriately diagnosing these conditions as there exists a variance in when these symptoms arise after radiation. However, we present key epidemiological data delineating vulnerable cancer populations for each pain syndrome along with the available evidence for the management for each specific condition.

Gastrointestinal cancers: the role of microbiota in carcinogenesis and the role of probiotics and microbiota in anti-cancer therapy efficacy

The gut epithelium is a habitat of a variety of microorganisms, including bacteria, fungi, viruses and Archaea. With the advent of sophisticated molecular techniques and bioinformatics tools, more information on the composition and thus function of gut microbiota was revealed. The gut microbiota as an integral part of the intestinal barrier has been shown to be involved in shaping the mucosal innate and adaptive immune response and to provide protection against pathogens. Consequently, a set of biochemical signals exchanged within microbes and communication between the microbiota and the host have opened a new way of thinking about cancer biology. Probiotics are living organisms which administered in adequate amounts may bring health benefits and have the potential to be an integral part of the prevention/treatment strategies in clinical approaches. Here we provide a comprehensive review of data linking gut microbiota to cancer pathogenesis and its clinical course. We focus on gastrointestinal cancers, such as gastric, colorectal, pancreatic and liver cancer.

Gut Microbiota as a Positive Potential Therapeutic Factor in Carcinogenesis: an Overview of Microbiota-Targeted Therapy

Cancer therapeutic methods comprising chemotherapy, radiotherapy, and surgery are so routine in cancer treatment. Remarkably, there are several personal features which affect the effectiveness of such treatments including nutrition, microbiome diversity, and physical activity which has distinct significant roles during and after therapies along with their bilateral connections. In this way, the ability of gut microbiota36 in modulating the efficacy of chemotherapeutic medications in cancer and other types of disorders is of great importance. In addition, the role of dietary, probiotic, and synthetically engineered bacteria in manipulating and optimizing the gut microbiota is of interest. Conspicuously, the correlation between the commensal microbiota and also host can regulate the physiological activities comprising the immunity system and inflammatory agents and it is scanned in the category of cancers. Bacterial species have been employed in cancer therapy; commensal microbes posse a key beneficial role in this field. Practically, the microbiota has this potential to accelerate and modulates a certain response by priming in order to release the pro-inflammatory agents. We would like to discuss these vital factors in this review as gut microbiota has the potential to be the main option for personalized cancer treatment strategies in the future. Meaning, this novel data present clinical promising feasibilities of modulating cancer therapy with using microbiota.

Microbiome-gut-brain axis in cancer treatment-related psychoneurological toxicities and symptoms: a systematic review

PURPOSE

The microbiome-gut-brain (MGB) axis provides a dynamic model to understand associations between the gut microbiota and psychoneurological comorbidities. The role of the MGB axis in cancer treatment-related psychoneurological symptoms (PNS) remains unknown. The purpose of this study was to conduct a systematic review of the existing literature to identify the influence of the gut microbiota on cancer and cancer treatment-related PNS and toxicities mediated by the MGB axis.

METHODS

We searched the databases of PubMed, Embase, and Web of Science from their earliest records to October 2019. All studies identified in the database searches were screened by title and abstract, followed by a review of the full texts. The Johns Hopkins Nursing Evidence-Based Practice Model was adopted to assess the evidence levels and qualities; the Joanna Briggs Institute critical appraisal tools were used to assess the methodological quality and the possibility of bias for each included study. All the study findings were combined, synthesized, and presented through narrative format.

RESULTS

Six studies were included in this systematic review. These studies primarily focused on cancer survivorship while receiving chemotherapy, and they were conducted between 2016 and 2019. The gut microbiome was assessed via fecal samples, which were analyzed using 16S rRNA sequencing approaches. With small-scale studies, the gut microbiota was associated with cancer treatment-related PNS, including fatigue, anxiety, depression, sleep disturbance, cognitive impairment, and chemotherapy-induced peripheral neuropathy. A higher relative abundance of Bacteroides was associated with a higher level of fear of cancer recurrence but a higher relative abundance of Lachnospiraceae.g and Ruminococcus was associated with a lower level in fear of cancer recurrence. Changes in fatigue interference were associated with the frequency of genera Faecalibacterium and Prevotella, and changes in anxiety were associated with the frequency of genera Coprococcus and Bacteroides.

CONCLUSIONS

The gut microbiota showed significant associations with cancer treatment-related PNS. Recent work regarding the MGB axis in cancer psychoneurological toxicities focused primarily on individual toxicity and symptoms in cancer survivors with chemotherapy exposure. Associations between the gut microbiota and PNS should be further studied in cancer populations across different ages, cancer types, and treatment modalities.

The Gut Microbiome Is Associated With Therapeutic Responses and Toxicities of Neoadjuvant Chemoradiotherapy in Rectal Cancer Patients-A Pilot Study

Responses to neoadjuvant chemoradiotherapy (nCRT) and therapy-related toxicities in rectal cancer vary among patients. To provide the individualized therapeutic option for each patient, predictive markers of therapeutic responses and toxicities are in critical need. We aimed to identify the association of gut microbiome with and its potential predictive value for therapeutic responses and toxicities. In the present study, we collected fecal microbiome samples from patients with rectal cancer at treatment initiation and just after nCRT. Taxonomic profiling via 16S ribosomal RNA gene sequencing was performed on all samples. Patients were classified as responders versus non-responders. Patients were grouped into no or mild diarrhea and severe diarrhea. STAMP and high-dimensional class comparisons via linear discriminant analysis of effect size (LEfSe) were used to compare the compositional differences between groups. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) was utilized to predict differences in metabolic function between groups. Ten patients were classified as responders and 12 patients were classified as non-responders. Fourteen patients experienced no or mild diarrhea and 8 patients experienced severe diarrhea. Several bacteria taxa with significantly different relative abundances before and after nCRT were identified. Similarly, several baseline bacteria taxa and predicted pathways with significantly different relative abundances between responders and non-responders or between patients no or mild diarrhea and severe diarrhea were identified. Specifically, Shuttleworthia was identified as enriched in responders and several bacteria taxa in the Clostridiales order etc. were identified as enriched in non-responders. Pathways including fatty acid metabolism were predicted to be enriched in responders. In addition, Bifidobacterium, Clostridia, and Bacteroides etc. were identified as enriched in patients with no or mild diarrhea. Pathways including primary bile acid biosynthesis were predicted to be enriched in patients with no or mild diarrhea. Together, the microbiota and pathway markers identified in this study may be utilized to predict the therapeutic responses and therapy-related toxicities of nCRT in patients with rectal cancer. More patient data is needed to verify the current findings and the results of metagenomic, metatranscriptomic, and metabolomic analyses will further mine key biomarkers at the compositional and functional level.

Bidirectional and dynamic interaction between the microbiota and therapeutic resistance in pancreatic cancer

Pancreatic ductal adenocarcinoma is one of the most lethal malignancies and is known for its high resistance and low response to treatment. Cancer treatments can reshape the microbiota and in turn, the microbiota influences the therapeutic efficacy by regulating immune response and metabolism. This crosstalk is bidirectional, heterogeneous, and dynamic. In this review, we elaborated on the interactions between the microbiota and therapeutic resistance in pancreatic ductal adenocarcinoma. Regulating the microbiota in pancreatic tumor microenvironment may not only generate direct anti-cancer but also synergistic effects with other treatments, providing new directions in cancer therapy.

Therapeutic methods of gut microbiota modification in colorectal cancer management - fecal microbiota transplantation, prebiotics, probiotics, and synbiotics

The link between gut microbiota and the development of colorectal cancer has been investigated. An imbalance in the gut microbiota promotes the progress of colorectal carcinogenesis via multiple mechanisms, including inflammation, activation of carcinogens, and tumorigenic pathways as well as damaging host DNA. Several therapeutic methods are available with which to alter the composition and the activity of gut microbiota, such as administration of prebiotics, probiotics, and synbiotics; these can confer various benefits for colorectal cancer patients. Nowadays, fecal microbiota transplantation is the most modern way of modulating the gut microbiota. Even though data regarding fecal microbiota transplantation in colorectal cancer patients are still rather limited, it has been approved as a clinical method of treatment-recurrent Clostridium difficile infection, which may also occur in these patients. The major benefits of fecal microbiota transplantation include modulation of immunotherapy efficacy, amelioration of bile acid metabolism, and restoration of intestinal microbial diversity. Nonetheless, more studies are needed to assess the long-term effects of fecal microbiota transplantation. In this review, the impact of gut microbiota on the efficiency of anti-cancer therapy and colorectal cancer patients' overall survival is also discussed.