The impact of pelvic radiotherapy on the gut microbiome and its role in radiation-induced diarrhoea: a systematic review

Intestinal microecological transplantation for a patient with chronic radiation enteritis: A case report

BACKGROUND

The gut microbiota is strongly associated with radiation-induced gut damage. This study aimed to assess the effectiveness and safety of intestinal microecological transplantation for treating patients with chronic radiation enteritis.

CASE SUMMARY

A 64-year-old female with cervical cancer developed abdominal pain, diarrhea, and blood in the stool 1 year after radiotherapy. An electronic colonoscopy was performed to diagnose chronic radiation enteritis. Two courses of intestinal microecological transplantation and full-length 16S rRNA microbiological analysis were performed. The patient experienced short- and long-term relief from symptoms without adverse effects. Whole 16S rRNA sequencing revealed significant differences in the intestinal flora's composition between patient and healthy donors. Pathogenic bacteria, such as Escherichia fergusonii and Romboutsia timonensis, were more in the patient. Beneficial bacteria such as Faecalibacterium prausnitzii, Fusicatenibacter saccharivorans, Ruminococcus bromii, and Bifidobacterium longum were more in the healthy donors. Intestinal microbiota transplantation resulted in a significant change in the patient's intestinal flora composition. The composition converged with the donor's flora, with an increase in core beneficial intestinal bacteria, such as Eubacterium rectale, and a decrease in pathogenic bacteria. Changes in the intestinal flora corresponded with the patients' alleviating clinical symptoms.

CONCLUSION

Intestinal microecological transplantation is an effective treatment for relieving the clinical symptoms of chronic radiation enteritis by altering the composition of the intestinal flora. This study provides a new approach for treating patients with chronic radiation enteritis.

Microbiome and Abdominopelvic Radiotherapy Related Chronic Enteritis: A Microbiome-based Mechanistic Role of Probiotics and Antibiotics

Chronic diarrhea and abdominal pain after radiotherapy continue to be a problem in cancer survivors. Gut microbiomes are essential for preventing intestinal inflammation, maintaining intestinal integrity, maintaining enterohepatic circulation, regulating bile acid metabolism, and absorption of nutrients, including fat-soluble vitamins. Gut microbiome dysbiosis is expected to cause inflammation, bile acid malabsorption, malnutrition, and associated symptoms. Postradiotherapy, Firmicutes and Bacteroidetes phylum are significantly decreased while Fusobacteria and other unclassified bacteria are increased. Available evidence suggests harmful bacteria Veillonella, Erysipelotrichaceae, and Ruminococcus are sensitive to Metronidazole or Ciprofloxacin. Beneficial bacteria lactobacillus and Bifidobacterium are relatively resistant to metronidazole. We hypothesize and provide an evidence-based review that short-course targeted antibiotics followed by specific probiotics may lead to alleviation of radiation enteritis.

Pelvic Floor Therapy and Initial Interventions for Pelvic Floor Dysfunction in Gynecologic Malignancies

PURPOSE OF REVIEW

This review provides evidence-based updates for the first-line management approaches for pelvic floor disorders in patients with gynecologic malignancies, as well as important provider considerations when referring for pelvic floor physical therapy.

RECENT FINDINGS

Currently, there is strong evidence to recommend pelvic floor muscle training as initial treatment for urinary incontinence and for pelvic organ prolapse; some evidence to recommend a more targeted pelvic floor muscle training program for fecal incontinence; and mostly expertise-based evidence to recommend vaginal gels or estrogen to aid with dyspareunia causing sexual dysfunction. More research is greatly needed to understand the role of overactive pelvic floor muscles in survivors with chronic pelvic pain and the treatment of post-radiation pelvic complications such as vaginal stenosis and cystitis. While pelvic floor disorders are common concerns in gynecologic cancer survivors, there are evidence-based initial noninvasive treatment approaches that can provide relief for many individuals.

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.

Human Intestinal Organoids and Microphysiological Systems for Modeling Radiotoxicity and Assessing Radioprotective Agents

Radiotherapy is a commonly employed treatment for colorectal cancer, yet its radiotoxicity-related impact on healthy tissues raises significant health concerns. This highlights the need to use radioprotective agents to mitigate these side effects. This review presents the current landscape of human translational radiobiology, outlining the limitations of existing models and proposing engineering solutions. We delve into radiotherapy principles, encompassing mechanisms of radiation-induced cell death and its influence on normal and cancerous colorectal cells. Furthermore, we explore the engineering aspects of microphysiological systems to represent radiotherapy-induced gastrointestinal toxicity and how to include the gut microbiota to study its role in treatment failure and success. This review ultimately highlights the main challenges and future pathways in translational research for pelvic radiotherapy-induced toxicity. This is achieved by developing a humanized in vitro model that mimics radiotherapy treatment conditions. An in vitro model should provide in-depth analyses of host-gut microbiota interactions and a deeper understanding of the underlying biological mechanisms of radioprotective food supplements. Additionally, it would be of great value if these models could produce high-throughput data using patient-derived samples to address the lack of human representability to complete clinical trials and improve patients' quality of life.

Longitudinal analysis at three oral sites links oral microbiota to clinical outcomes in allogeneic hematopoietic stem-cell transplant

IMPORTANCE

The oral cavity is the ultimate doorway for microbes entering the human body. We analyzed oral microbiota dynamics in allogeneic hematopoietic stem-cell transplant recipients and showed that microbiota injury and recovery patterns were highly informative on transplant complications and outcomes. Our results highlight the importance of tracking the recipient's microbiota changes during allogeneic hematopoietic stem-cell transplant to improve our understanding of its biology, safety, and efficacy.

Diarrheal-associated gut dysbiosis in cancer and inflammatory bowel disease patients is exacerbated by Clostridioides difficile infection

Introduction

Low diversity gut dysbiosis can take different forms depending on the disease context. In this study, we used shotgun metagenomic sequencing and gas chromatography-mass spectrometry (GC-MS) to compared the metagenomic and metabolomic profiles of Clostridioides (Clostridium) difficile diarrheal cancer and inflammatory bowel disease (IBD) patients and defined the additive effect of C. difficile infection (CDI) on intestinal dysbiosis.

Results

The study cohort consisted of 138 case-mix cancer patients, 43 IBD patients, and 45 healthy control individuals. Thirty-three patients were also infected with C. difficile. In the control group, three well-known enterotypes were identified, while the other groups presented with an additional Escherichia-driven enterotype. Bacterial diversity was significantly lower in all groups than in healthy controls, while the highest level of bacterial species richness was observed in cancer patients. Fifty-six bacterial species had abundance levels that differentiated diarrheal patient groups from the control group. Of these species, 52 and 4 (Bacteroides fragilis, Escherichia coli, Klebsiella pneumoniae, and Ruminococcus gnavus) were under-represented and over-represented, respectively, in all diarrheal patient groups. The relative abundances of propionate and butyrate were significantly lower in fecal samples from IBD and CDI patients than in control samples. Isobutyrate, propanate, and butyrate concentrations were lower in cancer, IBD, and CDI samples, respectively. Glycine and valine amino acids were over- represented in diarrheal patients.

Conclusion

Our data indicate that different external and internal factors drive comparable profiles of low diversity dysbiosis. While diarrheal-related low diversity dysbiosis may be a consequence of systemic cancer therapy, a similar phenotype is observed in cases of moderate to severe IBD, and in both cases, dysbiosis is exacerbated by incidence of CDI.

Characterization of Early and Late Damage in a Mouse Model of Pelvic Radiation Disease

Pelvic radiation disease (PRD), a frequent side effect in patients with abdominal/pelvic cancers treated with radiotherapy, remains an unmet medical need. Currently available preclinical models have limited applications for the investigation of PRD pathogenesis and possible therapeutic strategies. In order to select the most effective irradiation protocol for PRD induction in mice, we evaluated the efficacy of three different locally and fractionated X-ray exposures. Using the selected protocol (10 Gy/day × 4 days), we assessed PRD through tissue (number and length of colon crypts) and molecular (expression of genes involved in oxidative stress, cell damage, inflammation, and stem cell markers) analyses at short (3 h or 3 days after X-ray) and long (38 days after X-rays) post-irradiation times. The results show that a primary damage response in term of apoptosis, inflammation, and surrogate markers of oxidative stress was found, thus determining a consequent impairment of cell crypts differentiation and proliferation as well as a local inflammation and a bacterial translocation to mesenteric lymph nodes after several weeks post-irradiation. Changes were also found in microbiota composition, particularly in the relative abundance of dominant phyla, related families, and in alpha diversity indices, as an indication of dysbiotic conditions induced by irradiation. Fecal markers of intestinal inflammation, measured during the experimental timeline, identified lactoferrin, along with elastase, as useful non-invasive tools to monitor disease progression. Thus, our preclinical model may be useful to develop new therapeutic strategies for PRD treatment.

Gut microbiota: A novel and potential target for radioimmunotherapy in colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers, with a high mortality rate, and is a major burden on human health worldwide. Gut microbiota regulate human immunity and metabolism through producing numerous metabolites, which act as signaling molecules and substrates for metabolic reactions in various biological processes. The importance of host-gut microbiota interactions in immunometabolic mechanisms in CRC is increasingly recognized, and interest in modulating the microbiota to improve patient's response to therapy has been raising. However, the specific mechanisms by which gut microbiota interact with immunotherapy and radiotherapy remain incongruent. Here we review recent advances and discuss the feasibility of gut microbiota as a regulatory target to enhance the immunogenicity of CRC, improve the radiosensitivity of colorectal tumor cells and ameliorate complications such as radiotoxicity. Currently, great breakthroughs in the treatment of non-small cell lung cancer and others have been achieved by radioimmunotherapy, but radioimmunotherapy alone has not been effective in CRC patients. By summarizing the recent preclinical and clinical evidence and considering regulatory roles played by microflora in the gut, such as anti-tumor immunity, we discuss the potential of targeting gut microbiota to enhance the efficacy of radioimmunotherapy in CRC and expect this review can provide references and fresh ideas for the clinical application of this novel strategy.

Ginsenoside Rg3 treats acute radiation proctitis through the TLR4/MyD88/NF-κB pathway and regulation of intestinal flora

Objectives

This study aimed to investigate the protective effect of ginsenoside Rg3 (GRg3) against acute radiation proctitis (ARP) in rats.

Methods

Wistar rats were randomly divided into control, model, dexamethasone-positive, GRg3 low-dose, GRg3 medium-dose, and GRg3 high-dose groups. The ARP rat model was established by a single 22-Gy irradiation of 6 MV) X-rays. The distribution and function of intestinal flora were detected using 16S rRNA high-throughput sequencing, rectal tissue was observed by hematoxylin and eosin (H&E) staining, the expression of interleukin 1β (IL-1β) and IL-10 inflammatory factors was detected by ELISA, and mRNA and protein expression of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) were detected by RT-qPCR and Western blotting, respectively.

Results

GRg3 improved the symptoms of ARP in rats in a dose-dependent manner. The species distribution of intestinal flora in GRg3 rats was significantly different from that in ARP rats. These differences were more significant in the high-dose group, where the numbers of Ruminococcus, Lactobacillus, and other beneficial bacteria were significantly increased, whereas those of Escherichia, Alloprevotella, and other harmful bacteria were decreased. In addition, GRg3 was closely related to amino acid metabolism. After GRg3 treatment, the mRNA and protein expression of TLR4, MyD88, and NF-κB in rectal tissue was significantly down-regulated, and the level of downstream inflammatory factor IL-1β decreased, whereas that of IL-10 increased.

Conclusion

Our study indicated GRg3 as a new compound for the treatment of ARP by inhibiting the TLR4/MyD88/NF-κB pathway, down-regulating the expression of proinflammatory factors, thus effectively regulating intestinal flora and reducing inflammatory reactions.

New Insights into the Relationship between Gut Microbiota and Radiotherapy for Cancer

Cancer is the second most common cause of death among humans in the world, and the threat that it presents to human health is becoming more and more serious. The mechanisms of cancer development have not yet been fully elucidated, and new therapies are changing with each passing day. Evidence from the literature has validated the finding that the composition and modification of gut microbiota play an important role in the development of many different types of cancer. The results also demonstrate that there is a bidirectional interaction between the gut microbiota and radiotherapy treatments for cancer. In a nutshell, the modifications of the gut microbiota caused by radiotherapy have an effect on tumor radiosensitivity and, as a result, affect the efficacy of radiotherapy and show a certain radiation toxicity, which leads to numerous side effects. What is of new research significance is that the "gut-organ axis" formed by the gut microbiota may be one of the most interesting potential mechanisms, although the relevant research is still very limited. In this review, we combine new insights into the relationship between the gut microbiota, cancer, and radiotherapy. Based on our current comprehensive understanding of this relationship, we give an overview of the new cancer treatments based on the gut microbiota.

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.

The effect of chronoradiotherapy on cervical cancer patients: A multicenter randomized controlled study

OBJECTIVES

To investigate the short-term efficacy and radiotoxicity 3.543of chronoradiotherapy in patients with cervical cancer. We also examined the overall symptom score and quality of life (QOL) of patients who underwent morning radiotherapy and evening radiotherapy.

METHODS

We conducted a multicenter randomized controlled trial to compare the effects of morning radiotherapy (9:00-11:00 AM) with evening radiotherapy (7:00-9:00 PM) in cervical cancer patients receiving radiotherapy. From November 2021 to June 2022, 114 cervical cancer patients admitted to eight cancer center hospitals in Tianjin, Chongqing, Hubei, Shanxi, Shandong, Shaanxi, Hebei, and Cangzhou were randomly divided into the morning radiotherapy group (MG; N = 61) and the evening radiotherapy group (EG; N = 53). The short-term efficacy of radiotherapy on cervical cancer patients at different time points and the occurrence of radiotoxicity were explored after patients had undergone radiotherapy.

RESULTS

The total effective response (partial remission [PR] + complete remission [CR]) rate was similar across the two groups (93.5% vs. 96.3%, p > 0.05). However, the incidence of bone marrow suppression and intestinal reaction in the two groups were significantly different (p < 0.05). The patients in the MG had significantly higher Anderson symptom scores than patients in the EG (21.64 ± 7.916 vs. 18.53 ± 4.098, p < 0.05). In terms of physical activity, functional status, and overall QOL, the MG had significantly lower scores than the EG (p < 0.05). No other measures showed a significant difference between the groups.

CONCLUSION

The radiotherapy effect of the MG was consistent with that of the EG. The incidence of radiation enteritis and radiation diarrhea in the MG was significantly higher than that in the EG; however, bone marrow suppression and blood toxicity in the EG were more serious than in the MG. Because of the small sample size of the study, we only examined the short-term efficacy of radiotherapy. Therefore, further clinical trials are needed to verify the efficacy and side effects of chronoradiotherapy.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/searchproj.aspx, Registration Number: ChiCTR2100047140.

Dietary modulation of gut microbiota in patients with colorectal cancer undergoing surgery: A review

Colorectal cancer (CRC) is the third most frequent malignancy and the second cause of cancer death worldwide. Several factors have been postulated to be involved in CRC pathophysiology, including physical inactivity, unhealthy dietary habits, obesity, and the gut microbiota. Emerging data suggest that the microbiome may play a key role in CRC prognosis and derived complications in patients undergoing colorectal surgery. On the other hand, dietary intervention has been demonstrated to be able to induce significant changes in the gut microbiota and related metabolites in different conditions; therefore, the manipulation of gut microbiota through dietary intervention may constitute a useful approach to improve perioperative dysbiosis and post-surgical outcomes in patients with CRC. In this article, we review the role of the gut microbiota in CRC surgery complications and the potential therapeutic modulation of gut microbiome through nutritional intervention in patients with CRC undergoing surgery.

The Underestimated and Overlooked Burden of Diarrhea and Constipation in Cancer Patients

PURPOSE OF REVIEW

This review aims to summarize and discuss the diverse causes of two major gastrointestinal dysfunction symptoms, diarrhea and constipation, in cancer patients. We also discuss short- and long-term clinical, economic, and humanistic consequences, including the impact on cancer treatment regimens and patient quality of life, highlighting the limitations of the literature.

RECENT FINDINGS

Diarrhea and constipation as a result of cancer and its treatment can risk the success of anti-cancer therapies by requiring treatment delay or withdrawal, and imposes a substantial humanistic burden in patients with cancer. Despite its importance and frequency, gastrointestinal side effects may be overlooked due to the focus on cancer treatment, and the impact on patients may be underestimated. Additionally, the burden reported may not fully reflect current cancer management, particularly the true impact of economic consequences. A full understanding of the burden of diarrhea and constipation in patients with cancer is required, including broad evaluation of clinical considerations, the patient experience, and an updated assessment of economic burden. This would improve caregivers' appreciation of the impact of gastrointestinal dysfunction and aid the prioritization of future research efforts.