Oral Mucositis Due to High-Dose Chemotherapy and/or Head and Neck Radiation Therapy

Oral Complications and Management Strategies for Cancer Patients: Principles of Supportive Oncology in Dentistry

PURPOSE OF REVIEW

It is recognized that patients undergoing cancer treatment experience different adverse effects depending on the type of therapy they received. The objective of this work is to provide a scientific evidence-based protocol for oral care in cancer patients. Cancer resection surgery, chemotherapy, and radiotherapy can cause important complications that impact patients' quality of life.

RECENT FINDINGS

Cancer patients, from the moment of diagnosis to the end of treatment and subsequent follow-up, have diverse care needs, both from a systemic and local point of view. The implementation of oral care protocols before, during, and after cancer therapy is essential because it helps to identify risk factors for the development of predictable oral complications. It is essential to establish that all cancer patients, before starting treatment, undergo a systematic dental check-up to avoid limitations during treatment and also alter their quality of life. Regular professional oral care maintenance and follow-up programs are essential to maintaining a patient's long-term oral health.

Evidence summary on managing radiotherapy-induced oral mucositis in patients with head and neck cancer

Objective

To summarize the best evidence for managing radiotherapy-induced oral mucositis in patients with head and neck cancer, and improve the quality of care.

Methods

According to the "6S" evidence pyramid model, we searched local and other part of world published clinical guidelines, expert consensus, evidence summary, and systematic review. The literature quality assessment followed the Appraisal of Guidelines for Research and Evaluation (AGREE II). for guidelines, AMSTAR-2 for systematic reviews, and Joanna Briggs Institute (JBI) Evidence-Based Health Care Center's quality evaluation tool for expert opinions and expert consensus articles. The quality of other literature was evaluated according to the type of original literature. If there were any conflicts about the conclusions drawn from different sources of evidence, this study followed the principle of high-quality evidence priority and the latest published authoritative literature priority. The "JBI Evidence Pre-grading and Evidence Recommendation Level System 2014" was adopted for the evidence lacking a grading system. Quality evaluation, evidence extraction, and summary were performed by 2 or more researchers, combined with the advice of the head and neck cancer radiotherapy professionals.

Results

Finally, a total of ten pieces of literature were included. Twenty-two best evidence items for radiotherapy-induced oral mucositis management were summarized from six aspects, including multidisciplinary management, oral assessment, basic oral care, pain management, nutritional support, and application of honey or propolis.

Conclusions

This study provides clinical caregivers with the evidence-based measures on managing radiotherapy-induced oral mucositis. Clinical backgrounds, patients' condition, willingness, economy, and cost-effectiveness should be fully considered when promoting evidence transformation. Applying evidence-based approaches with high feasibility, strong appropriateness, clinical significance and high effectiveness could reduce the incidence of severe radiotherapy-induced oral mucositis in patients with head and neck cancer.

Systematic review registration

This study has been registered on the Fudan University Centre for Evidence-based Nursing. Registration No. is ES20232732.

Monte Carlo based dosimetry of extraoral photobiomodulation for prevention of oral mucositis

Photobiomodulation therapy (PBMT) is recommended for prevention and treatment of oral mucositis, a painful condition that occurs in cancer patients. Intraoral PBMT is limited to treating distal oral mucosa and oropharynx. Extraoral PBMT may provide a more efficient intervention. The goal of this study was to develop a clinically viable protocol for extraoral PBMT. Monte Carlo modeling was used to predict the distribution of 850 nm light for four treatment sites, using anatomical data obtained from MRI and optical properties from the literature. Simulated incident light power density was limited to 399 mW/cm2 to ensure treatment safety and to prevent tissue temperature increase. The results reveal that total tissue thickness determines fluence rate at the oral mucosa, whereas the thickness of individual tissue layers and melanin content are of minor importance. Due to anatomical differences, the fluence rate varied greatly among patients. Despite these variations, a universal protocol was established using a median treatment time methodology. The determined median treatment times required to deliver efficacious dose between 1 and 6 J/cm2 were within 15 min. The developed PBMT protocol can be further refined using the combination of pretreatment imaging and the Monte Carlo simulation approach implemented in this study.

Hangeshashinto for prevention of oral mucositis in patients undergoing hematopoietic stem cell transplantation: a randomized phase II study

PURPOSE

Oral mucositis (OM) is a side effect associated with cancer treatment. Hangeshashinto (HST), a Kampo medicine, was originally prescribed to treat diarrhea, gastritis, and stomatitis. Several reports have described the effects of HST for OM induced by chemotherapy in patients with gastric or colorectal cancer. In this study, the effects of HST for prevention of OM were investigated in patients undergoing hematopoietic stem cell transplantation (HSCT).

METHODS

Thirty patients scheduled to receive allogeneic grafts were enrolled from July 2020 to December 2021. They were randomly assigned to two groups and instructed to wash their mouth using HST dissolved in saline solution or using only saline solution three times a day. The observation period was from the initiation date of the conditioning regimen to the date of engraftment, and the end point was the incidence of OM.

RESULTS

Eighteen patients developed OM, the most severe of which was Grade (G)3. There was no significant difference in the incidence of OM between the HST group and the control group. However, a negative correlation tended to be observed between the duration using HST use and the duration of OM (G2-3: P = 0.027, G3: P = 0.047).

CONCLUSIONS

The present study demonstrated that HST use did not clearly inhibit onset of OM but showed a tendency to inhibit OM exacerbation. However, further studies are necessary to fully understand the effects of HST on OM in patients undergoing HSCT.

TRIAL REGISTRATION

This study was registered in the Japan Registry of Clinical Trials on 7 May 2020 (jRCTs071200012).

Hemodynamics of the oral mucosa during cooling: A crossover clinical trial

Objective

Oral cryotherapy is used to prevent the onset of oral mucositis, a common and debilitating adverse effect following cancer chemotherapy. A protective mechanism associated with oral cooling is thought to be mediated through reduced tissue microcirculation. The aim of the present study was to examine the underlying mechanism associated with oral mucosal cooling by measuring oral microcirculation and tissue oxygen saturation after cooling with ice chips (IC) and an intraoral cooling device (ICD).

Study design

In a single-center randomized crossover study, 10 healthy volunteers were assigned (1:1) randomly to the order in which the two intraoral cooling procedures (IC/ICD) were to be commenced. On day 1, half of the study participants started with IC and then crossed over to intraoral cooling with the ICD on day 2, while the other half of the participants undertook the same two procedures in the reverse order. Total and functional capillary density (T/FCD) and tissue oxygen saturation (StO2) measurements were obtained at baseline and 30 min following oral cooling.

Results

Following 30 min of oral cooling, a statistically significant difference was found for FCD between IC and ICD (percentage points; +2 vs. -13; p < 0.05). A statistically significant decrease in StO2 was observed with both IC and ICD (%; 13 vs. 10) after 30 min of cooling as compared to baseline (p < 0.05). As for the participants' preference the ICD was preferred over IC by 9 out of 10 participants (p = 0.021).

Conclusions

Both microcirculation parameters and tissue oxygen saturation are altered in conjunction with oral cooling, indicating their potential mechanistic contribution towards cryoprevention of oral mucositis.

Precision medicine for risk prediction of oral complications of cancer therapy–The example of oral mucositis in patients receiving radiation therapy for cancers of the head and neck

Oral complications of cancer therapy are common, markedly symptomatic, negatively impact patients' quality of life, and add significantly to the cost of care. Patients' risk of treatment-related toxicities is not uniform; most patients suffer at least one side effect, while others tolerate treatment without any. Understanding those factors which impact risk provides opportunities to customize cancer treatment plans to optimize tumor kill and minimize regimen-related toxicities. Oral mucositis (OM) is an iconic example of a clinically significant and common complication of head and neck radiotherapy. Individuals' OM risk is governed by the cumulative impact of factors related to treatment, the tumor, and the patient. In addition to OM risk prediction, a second opportunity to apply precision medicine will evolve as viable treatment options become available. Patients vary widely in how well or poorly they respond to specific treatments. What works well in one individual, might fail in another. Prospective determination of the likelihood of a patient's response or non-response is based on a range of biological interactions. Coupled with risk determination, the application of precision medicine will allow caregivers, patients, and payers to integrate risk/benefit to optimize the probability that the best treatment is be given to the most appropriate patients.

Regulation of interleukin-6 and matrix metalloproteinases syntheses by bioflavonoids and photobiomodulation in human gingival fibroblasts

This study aimed to evaluate the separately effects of bioflavonoids proanthocyanidins, from grape seed extract (GSE) and synthetic naringenin (NA), as well as photobiomodulation (PBM) by low-level laser therapy on interleukin (IL)-6 and matrix metalloproteinases (MMPs) syntheses by human gingival fibroblasts (HGF). For this purpose, a connective tissue exposure (ulceration) model of HGF, stimulated with tumor necrosis factor-alpha (TNF-α), was used. Initially, the highest non-cytotoxic and non-genotoxic concentrations of bioflavonoids were determined by cell viability and micronuclei formation assays. Then, HGF were exposed to different stimuli: culture medium (negative control), dimethyl sulfoxide (DMSO), TNF-α, NA, GSE, TNF-α + NA, TNF-α + GSE, PBM (3 J/cm², 0.025 W, 780 nm), and TNF-α + PBM. Next, IL-6, MMP-2, and MMP-9 syntheses were assessed. The concentration of 10 μg/mL of bioflavonoids increased cell viability at 24 and 48 h and did not present cytotoxic or genotoxic effects on HGF after 24, 48, and 72 h of contact. This concentration was selected for the assessment of bioflavonoids potential in modulating inflammatory mediators. TNF-α exposure enhanced IL-6 (170%), MMP-2 (10%), and MMP-9 (20%) syntheses, while a decrease of MMP-2 by 55% after exposure to TNF-α + GSE and 20% after TNF-α + NA and TNF-α + PBM was observed. MMP-9 synthesis was decreased by 35% after TNF-α + NA, 20% after TNF-α + GSE, and 30% after PBM. IL-6 was down-regulated by GSE in the presence of TNF-α (80%). In conclusion, TNF-α up-regulated IL-6 and MMPs, while bioflavonoids and PBM down-regulated MMP-2 and MMP-9 syntheses; GSE also decreased IL-6 synthesis, demonstrating the individual promising potential of these therapies for ulceration management.

Anti-inflammatory mouthwashes for the prevention of oral mucositis in cancer therapy: an integrative review and meta-analysis

PURPOSE

Mucositis is severely painful and often reported as one of the most distressing adverse effects of cancer therapy; it is a significant threat to quality of life as well as life itself. Anti-inflammatory agents may modulate physiologic mechanisms that perpetuate mucositis and be useful in prevention efforts. Because systemic anti-inflammatory agents are not appropriate for many patients, locally acting agents (mouthwashes) may be more feasible for use. This review and meta-analysis evaluates the role that anti-inflammatory mouthwashes have in preventing or reducing oral mucositis associated with chemotherapy and radiation therapy.

METHODS

A systematic literature review was conducted to identify studies evaluating the efficacy of anti-inflammatory mouthwashes to prevent therapy-associated mucositis. Meta-analysis was conducted to determine efficacy in preventing any mucositis and dose-limiting mucositis.

RESULTS

Eight peer-reviewed publications were identified; corticosteroid and nonsteroidal anti-inflammatory mouthwashes are effective in reducing overall incidence of mucositis and are associated with lower severity of mucositis. Meta-analysis reveals significant reduction in symptomatic mucositis incidence (OR 6.00, 95% CI 4.39-8.20, p < 0.0001) and reduction of dose-limiting mucositis (OR 2.12, 95% CI 1.07-4.28, p = 0.032).

CONCLUSION

Mouthwashes containing anti-inflammatory agents are a potential effective means to prevent or reduce mucositis associated with cancer therapy. There are limited adverse effects from these agents, and adherence is high, indicating safety and feasibility of use. Anti-inflammatory mouthwashes should be considered for supportive care in persons at risk for mucositis and must be further evaluated to investigate efficacy across multiple chemotherapy agents, adverse effects, and impacts on symptoms, pain, and quality of life.

Effects of an oral mucosa protective formulation on chemotherapy- and/or radiotherapy-induced oral mucositis: a prospective study

Background

Oral mucositis (OM) associated with cancer treatment not only impairs patients’ quality of life but also causes treatment delays or changes. This prospective exploratory study was conducted to evaluate the efficacy of Episil® oral liquid, which is an approved protective formulation for the oral mucosa in patients with OM. The extent of the pain-relieving effect, feeling during use, and adverse events or problems were evaluated.

Methods

In total, 10 Japanese cancer patients with OM receiving chemotherapy, pretreatment therapy for hematopoietic stem cell transplantation, or radiation therapy for head and neck cancer were enrolled.

Results

A numerical rating scale (NRS) was used to assess oral pain intensity due to OM. Compared to baseline, the mean NRS began to decrease at 5 min after using Episil® (7.1 ± 1.4 to 4.6 ± 2.87; p = 0.264). A significant decrease was observed in the pain score after using Episil® compared with that before using Episil®, and this effect lasted up to 120 min. The protective effects of Episil® were observed 3–5 min after application. Some patients felt slight soreness or discomfort when applying Episil®. However, this discomfort due to Episil®’s stimulation was within the allowable range and transient. No adverse events were observed in any of the cases.

Conclusions

The results of this prospective study showed that Episil® could be an effective treatment to relieve oral pain in Japanese patients with moderate to severe OM, and this newly approved product might adequately support patients’ oral intake.

Trial registration

University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) (UMIN000031921).

Preventive effects of betamethasone valerate ointment for radiation-induced severe oral mucositis in patients with oral or oropharyngeal cancer: protocol for a multicentre, phase II, randomised controlled trial (Bet-ROM study)

INTRODUCTION

This is a randomised, multi-centre, open-label, phase II study to evaluate the efficacy of betamethasone valerate ointment on radiation-induced oral mucositis in patients with head and neck cancer undergoing concomitant radiotherapy with cisplatin or cetuximab.

METHODS AND ANALYSIS

The trial will take place at seven hospitals in Japan. Patients will be randomised (1:1) into betamethasone and control groups after the occurrence of grade 1 oral mucositis. In the betamethasone group, patients will use betamethasone valerate ointment five times a day, in addition to usual oral hygiene guidance. The primary endpoint is the incidence and onset time of grade 3 oral mucositis. The secondary endpoints are the incidence and onset time of grade 2 oral mucositis, incidence and onset time of oral candidiasis, completion of radiation therapy and adverse events. Target accrual is 102 patients with a two-sided type I error rate of 5% and 80% power to detect an 80% risk reduction in the incidence of grade 3 oral mucositis.

ETHICS AND DISSEMINATION

This study was approved by the Clinical Research Review Board of Nagasaki University (No. CRB20-009). All participants will be required to provide written informed consent. Findings will be disseminated through scientific and professional conferences and peer-reviewed journal publication. The datasets generated during the study will be available from the corresponding author on reasonable request.

TRIAL REGISTRATION NUMBER

jRCTs071200013.

Paradoxical role of interleukin-33/suppressor of tumorigenicity 2 in colorectal carcinogenesis: Progress and therapeutic potential

Colorectal cancer (CRC) is presently the second most prevalent global mortality-inducing cancer. CRC carcinogenesis is a multifactorial process involving internal genetic mutations and the external environment. In addition, non-neoplastic cell activities within tumor microenvironments for CRC development have been established. However, interleukin (IL)-33, secreted by such cell types, plays a pivotal role in cancer progression due to interaction with cellular constituents within the tumor-inflammation microenvironment. IL-33 belongs to the IL-1 cytokine family and acts as binding attachments for the suppressor of tumorigenicity (ST)2 receptor. Therefore, how to coordinate tumor microenvironment, design and optimize treatment strategies suitable for CRC, based on IL-33/ST2 signal is a challenge. Even though it has established influences upon immunity-linked conditions, IL-33 effects on CRC progression and prevention and related mechanisms are still controversial. Our review depicts controversial activities for IL-33/ST2 within carcinogenesis and cancer prevention. Moreover, IL-33/ST2 signaling is a potential therapeutic target for CRC.

Variations in pain prevalence, severity, and analgesic use by duration of survivorship: a cross-sectional study of 505 post-treatment head and neck cancer survivors

BACKGROUND

Studies suggest a high prevalence of pain in head and neck cancer (HNC) patients at diagnosis, during and after treatment; however, these studies had small sample sizes and did not comprehensively assess factors known to influence pain. We surveyed a large cohort of HNC survivors to determine variations in the prevalence of pain, its treatment and management by duration of survivorship, and assessed a comprehensive list of risk factors.

METHODS

A cross sectional survey of post-treatment survivors of HNC during routine follow-up clinic visits.

RESULTS

A total of 505 HNC survivors with a median follow up of 3 years from cancer diagnosis were included in the study. Overall, 45% (n = 224) reported pain and 14.5, 22 and 7% reported use of prescribed pain medication, over-the-counter pain medication and alternative pain therapies, respectively. Prevalence of severe pain was 7.3% and did not vary significantly by years of survivorship (< 1 year = 5.7%; 1 to < 3 years = 7.1%; 3 to < 8 years = 7.6%; 8 years or more =9.7%; P = 0.392). However, use of prescribed pain medication significantly varied by years of survivorship (< 1 year = 45.7%; 1 to < 3 years = 24.6%; 3 to < 8 years = 18.9; 8 years or more = 18.3%; p < 0.001). Of note, a significant proportion of survivors reported moderate to severe pain (moderate to severe = 55.7% versus none to mild = 44.3%) despite step 3 analgesic use (p < 0.001). Multivariable regression shows that recurrent disease (OR 6.77, 95% CI [1.44, 31.80]), history of chemotherapy (OR 6.00, 95% CI [2.10, 17.14]), and depression (Mild-moderate OR 5.30, 95% CI [2.20, 12.78]; Major OR 8.00, 95% CI [2.67, 23.96]) were significant risk factors for severe pain.

CONCLUSIONS

We identified a high prevalence of pain among HNC survivors and determined that analgesic use varied by the duration of survivorship. Therefore, routine surveillance for pain must be consistent throughout the course of survivorship.

Quercetin Prevents Radiation-Induced Oral Mucositis by Upregulating BMI-1

Radiation-induced oral mucositis is a major adverse event of radiotherapy. Severe oral mucositis may cause unwanted interruption in radiotherapy and reduce long-term survival in cancer patients receiving radiotherapy, but until now, there have been no effective options for preventing radiation-induced oral mucositis. Quercetin is a flavonoid that is widely found in food species and has anti-inflammatory, antioxidant, and anticancer activities. In this study, we investigated a new role of quercetin in preventing radiation-induced oral mucositis. Quercetin exerted preventive effects against radiation-induced oral mucositis induced by single-dose (25 Gy) ionizing radiation or fractionated ionizing radiation (8 Gy × 3) in C57BL/6 mice and maintained the proliferation ability of basal epithelial cells. Quercetin pretreatment alleviated reactive oxygen species generation, NF-κB pathway activation, and downstream proinflammatory cytokine production and reduced DNA double-strand breaks and cellular senescence induced by ionizing radiation. Quercetin also upregulated BMI-1 expression in oral epithelial cells and promoted ulcer repair. In addition, quercetin exerted similar radioprotective effects in irradiated primary cultured normal human keratinocytes, reduced reactive oxygen species generation and proinflammatory cytokine release, and promoted DNA double-strand break repair and wound healing by upregulating the expression of BMI-1, which is a polycomb group protein. Thus, quercetin can block multiple pathological processes of radiation-induced oral mucositis by targeting BMI-1 and may be a potential treatment option for preventing radiation-induced oral mucositis.

A hypothesis for the pathogenesis of radiation-induced oral mucositis: when biological challenges exceed physiologic protective mechanisms. Implications for pharmacological prevention and treatment

Oral mucositis (OM) remains a significant unmet need for patients being treated with standard concomitant chemoradiation (CRT) regimens for head and neck cancers (HNC). OM's pathogenesis is complex and includes both direct and indirect damage pathways. In this paper, the field is reviewed with emphasis on the initiating and sustaining role of oxidative stress on OM's pathobiology. A hypothesis is presented which suggests that based on OM's clinical and biological trajectory, mucosal damage is largely the consequence of cumulative CRT-induced biological changes overwhelming physiologic self-protective mechanisms. Furthermore, an individual's ability to mount and maintain a protective response is dependent on interacting pathways which are primarily determined by a multiplex consisting of genomics, epigenomics, and microbiomics. Effective biologic or pharmacologic OM interventions are likely to supplement or stimulate existing physiologic damage-control mechanisms.

Cytokine-Mediated Inflammation in the Oral Cavity and Its Effect on Lipid Nanocarriers

Topical drug administration to the oral mucosa proves to be a promising treatment alternative for inflammatory diseases. However, disease-related changes in the cell barrier must be considered when developing such delivery systems. This study aimed at investigating the changes in the lining mucosa caused by inflammation and evaluating the consequences on drug delivery systems such as nanostructured lipid carriers (NLC). For this, TR146 cells were treated with inflammatory cytokines and bacterial components. Cell viability and integrity, reactive oxygen species (ROS), and interleukin (IL)-8 release were used as endpoints to assess inflammation. Translocation of phosphatidylserine, cytoskeletal arrangement, opening of desmosomes, and cell proliferation were examined. Transport studies with NLC were performed considering active and passive pathways. The results showed that IL-1ß and tumor necrosis factor α induced inflammation by increasing IL-8 and ROS production (22-fold and 2-fold). Morphologically, loss of cell–cell connections and formation of stress fibers and hyperplasia were observed. The charge of the cell membrane shifted from neutral to negative, which increased the absorption of NLC due to the repulsive interactions between the hydrophobic negative particles and the cell membrane on the one hand, and interactions with lipophilic membrane proteins such as caveolin on the other.

A systematic review of interventions to mitigate radiotherapy-induced oral mucositis in head and neck cancer patients

BACKGROUND

Oral mucositis is a debilitating consequence of radiotherapy in patients with head and neck cancers. Radiation-induced oral mucositis (RIOM) can cause pain and weight loss, reduce quality of life and affect treatment outcomes.

METHODS

A systematic review was undertaken to identify and examine the efficacy of low-cost interventions to mitigate RIOM and to develop clinical guidelines based on the evidence.

RESULTS

The author identified three interventions: benzydamine hydrochloride mouth rinse (BHM), honey and oral glutamine (OG). The search identified twenty-four studies in total. Four studies examined BHM; all findings were favourable, although only one had moderate methodological quality, and the rest were low. The product was poorly tolerated by some participants in one study. Twelve studies examined honey. Eleven of these had favourable results; two studies had moderate methodological quality, and the rest were low. Eight studies examined OG. Six of these had favourable results; two studies had moderate methodological quality, and the rest were low.

CONCLUSION

The author cannot recommend BHM to mitigate RIOM due to the overall low quality of the studies and poor tolerance to the product. The author cannot recommend honey to mitigate RIOM due to weak evidence supporting the intervention. The author can recommend OG to mitigate RIOM. There is a need for high-quality studies with a consensus of the methodology to reduce heterogeneity and examination of the cost-effectiveness of the interventions.

Radiation-induced oral mucositis hamster model using a linear accelerator enhances clinical relevance of preclinical studies for treatment strategy investigation

Translational animal models for oral mucositis (OM) are necessary to simulate and assess the bioclinical effects and response in humans. These models should simulate high levels of radiation exposure that leads to oxidative stress and inflammatory-initiated tissue changes. Hamster models have been extensively studied to observe pathological effects of radiation exposure and help in the development of effective treatments. To successfully evaluate the potential for treatment regimens with consistency and relevance, a radiation-induced OM hamster model was developed using a clinical linear accelerator utilized by cancer patients daily. The dose exposure to the isolated, everted cheek pouch of a hamster, as well as the progression of injury, pro-inflammatory marker, histological, and elasticity analyses of the buccal pouch were conducted to verify replicability and reproducibility of the injury model. The findings from this model demonstrated its ability to consistently induce injury and resolution over 28 days using an acute dose of 60 Gy. This model was developed to enhance clinical relevance when evaluating potential efficacious treatments and can now be utilized in efficacy studies to better evaluate developed therapeutics in a preclinical model that is easy to translate to clinical studies..

Lactobacillus reuteri DSM 17938 and ATCC PTA 5289 ameliorates chemotherapy-induced oral mucositis

Oral mucositis (OM) is a common complication of cancer therapy, however OM management remains unsatisfactory. There is a growing interest in the therapeutic potential of probiotics in OM due to positive findings of its use in intestinal mucositis. This study aimed to determine the efficacy and safety of the probiotic combination Lactobacillus reuteri DSM 17938 and ATCC PTA 5289 strains in chemotherapy-induced OM. Mice were divided into 4 groups. PBS/water and PBS/LR groups comprised of mice injected with PBS intraperitoneally (i.p.), and were given water or the mixture of L. reuteri (LR) DSM 17938 and ATCC PTA 5289 in water respectively. The 5-FU/water and 5-FU/LR groups comprised of mice injected with 5-FU i.p., and were given water or L. reuteri DSM 17938 and ATCC PTA 5289 in water respectively. Histopathological analysis revealed that the oral epithelia of the 5-FU/water and 5-FU/LR groups were thinner compared to PBS/water and PBS/LR groups. However, epithelial damage was significantly reduced in the 5-FU/LR compared to 5-FU/water group. Additionally, the 5-FU/LR group showed reduced oxidative stress and inflammation in the oral mucosa. We further showed that L. reuteri reduced oxidative stress through the nuclear factor E2-related factor-2 (Nrf-2) signalling. There was no evidence of translocation of L. reuteri systemically. This study demonstrated for the first time that L. reuteri protected oral mucosa against damage induced by chemotherapy.

Glutamine for Amelioration of Radiation and Chemotherapy Associated Mucositis during Cancer Therapy

Glutamine is a major dietary amino acid that is both a fuel and nitrogen donor for healing tissues damaged by chemotherapy and radiation. Evidence supports the benefit of oral (enteral) glutamine to reduce symptoms and improve and/or maintain quality of life of cancer patients. Benefits include not only better nutrition, but also decreased mucosal damage (mucositis, stomatitis, pharyngitis, esophagitis, and enteritis). Glutamine supplementation in a high protein diet (10 grams/day) + disaccharides, such as sucrose and/or trehalose, is a combination that increases glutamine uptake by mucosal cells. This increased topical effect can reduce painful mucosal symptoms and ulceration associated with chemotherapy and radiation in the head and neck region, esophagus, stomach and small intestine. Topical and oral glutamine seem to be the preferred routes for this amino acid to promote mucosal healing during and after cancer treatment.

Oral Mucositis: An Update on Innate Immunity and New Interventional Targets

Oral mucositis (OM), a common debilitating toxicity associated with chemo- and radiation therapies, is a significant unmet clinical need for head and neck cancer patients. The biological complexities of chemoradiotherapy-induced OM involve interactions among disrupted tissue structures, inflammatory infiltrations, and oral microbiome, whereby several master inflammatory pathways constitute the complicated regulatory networks. Oral mucosal damages triggered by chemoradiotherapy-induced cell apoptosis were further exacerbated by the amplified inflammatory cascades dominantly governed by the innate immune responses. The coexistence of microbiome and innate immune components in oral mucosal barriers indicates that a signaling hub coordinates the interaction between environmental cues and host cells during tissue and immune homeostasis. Dysbiotic shifts in oral microbiota caused by cytotoxic cancer therapies may also contribute to the progression and severity of chemoradiotherapy-induced OM. In this review, we have updated the mechanisms involving innate immunity-governed inflammatory cascades in the pathobiology of chemoradiotherapy-induced OM and the development of new interventional targets for the management of this severe morbidity in head and neck cancer patients.