Oral microbiome as a new research-target for supportive care and precision oncology.

PURPOSE OF REVIEW: A growing number of studies demonstrate the oral bacterial shift in cancer patients and the enrichment of oral bacteria in distant tumours. During the oncological treatment, opportunistic oral bacteria correlate with oral toxicities. This review focused on the most recent studies to identify which genera are the most mentioned and deserved further investigation. RECENT FINDINGS: This review evaluated bacterial changes in patients with head and neck, colorectal, lung and breast cancer. Greater composition of disease-related genera (e.g., Fusobacterium , Porphyromonas , Lactobacillus , Streptococcus , and Parvimonas ) are present in the oral cavity of these groups of patients. The tumour specimen characterisation of head and neck, pancreatic and colorectal cancer also describes the presence of oral taxa. No evidence indicates that commensal oral bacteria have protective roles in distant tumours. Regardless, oral care is critical to prevent the growth of oral pathogens and reduce infection foci. SUMMARY: Recent evidence suggests that oral microbiota is a potential biomarker for oncological clinical outcomes and oral toxicities. Currently, the literature presents a remarkable methodological variety - from the sample collection site to the preference of the data analysis tools. For the oral microbiome to achieve the stage of being used as a clinical tool in the oncological context, more studies are necessary.

Evaluation of halitosis parameters in patients undergoing head and neck radiotherapy.

OBJECTIVES: To assess halitosis parameters using OralChroma™ and the correlation with salivary flow, oral hygiene index, radiation dose, and tongue-coating index among irradiated head and neck cancer patients compared to patients without cancer. MATERIALS AND METHODS: This cross-sectional study enrolled irradiated and non-irradiated patients divided into two groups. Hydrogen sulfide, methyl mercaptan, and dimethyl sulfide (DMS) levels were measured using a gas chromatograph, and sialometry was performed. The tongue-coating index and simplified oral hygiene index were also assessed. RESULTS: Thirty-eight patients were allocated to each group. Volatile sulfur compound levels were above the thresholds in both groups. Non-irradiated individuals showed higher levels of hydrogen sulfide and dimethyl sulfide. Patients with asialia had an inexpressive tongue-coating index and increased dimethyl sulfide levels. A decrease in salivary flow rate was followed by a significant increase in volatile sulfur compound levels. Higher doses of radiation to the submandibular salivary glands were associated with higher concentrations of sulfide and methyl mercaptan. CONCLUSIONS: Head and neck radiotherapy may be important in the development of halitosis. Irradiated patients with asialia presented insignificant lingual biofilm. Consequently, lower levels of volatile sulfur compounds were detected in this group. Asialia, a severe radiation-induced hyposalivation, impacted the levels of DMS (extraoral origin).

Oral shedding of herpesviruses and clinical outcomes in hematopoietic stem cell transplant patients.

OBJECTIVES: To characterize the oral shedding of herpes viruses in patients who underwent allogeneic hematopoietic stem cell transplantation (alloHSCT) and investigate its relationship with clinical outcomes. MATERIALS AND METHODS: Polymerase chain reaction and enzymatic digestion were performed to identify the oral shedding of the members of the Herpesviridae family in 31 patients. The samples were collected from the oral cavity at five timestamps. RESULTS: The presence of each herpesvirus in the oral cavity was observed in 3.2%, 12.9%, 19.3%, 32.2%, 54.8% and 93.5% patients for human herpesvirus (HHV)-6A, herpes simplex virus-1, HHV-6B, cytomegalovirus (CMV), Epstein-Barr virus (EBV) and HHV-7, respectively. Oral shedding of herpes virus was not uncommon after alloHSCT. There was a statistically significant association between the EBV and CMV oral shedding at C1 and the cumulative incidence of acute graft-versus-host disease (aGVHD). The results suggested that the presence of HSV-1 at C2 was related to a relapse. The HHV-7 oral shedding at C2 suggests a possible link between relapse, progression-free survival and overall survival of the patients. CONCLUSIONS: Patients who developed aGVHD showed higher CMV and EBV shedding in the oral cavity at aplasia, suggesting modifications to the pattern of immune cell response and inflammatory microenvironment.

Unusual gingival actinomycosis post allogeneic hematopoietic stem-cell transplant: case report.

BACKGROUND: Allogeneic hematopoietic stem cell transplant (allo-HSCT) is used to treat several hematological diseases, but immunosuppression during allo-HSCT facilitates opportunistic microbial growth in tissues, such as actinomycosis. An effective diagnosis of opportunistic diseases is essential for correct management of the disease and preservation of the immunosuppressed patient's life. CASE DESCRIPTION: A 57-year-old female patient was diagnosed with extranodal nasal type NK/T cell lymphoma and underwent curative treatment with allo-HSCT. Twenty-one days after the last clinical follow-up, the patient presented a necrotizing lesion in the papilla region between the first and second molars of the second quadrant. Histopathological analysis showed the presence of a bacterial cluster consistent with Actinomyces infection, and a dense lymphoid infiltrate was also observed. Immunohistochemistry for CD20, CD3, and CD56 was performed to exclude the possibility of the recurrence of extranodal NK/T cell lymphoma. Oral microbiota profiling showed a huge increase in the abundance of Actinomyces bacteria in the subgingival region three weeks prior to appearance of the lesion. CONCLUSIONS: Opportunistic infections with an unusual clinical appearance are confounding factors in therapeutic decision-making. We present for the first time a case of actinomycosis in the gingival papilla region following allo-HSCT. We also highlight how microbiota profiling through next-generation sequencing could be used to anticipate bacterial infection diagnosis.

Oral mucositis in paediatric cancer patients undergoing allogeneic hematopoietic stem cell transplantation preventively treated with professional dental care and photobiomodulation: Incidence and risk factors.

BACKGROUND: Oral mucositis (OM) is an important side effect related to allogeneic hematopoietic stem cell transplantation (allo-HSCT), and it has been associated with a significative reduction of quality of life. A negative impact of OM in paediatric patients could result in increased use of parenteral feeding and opioids, longer periods of hospitalization, and a higher risk of systemic infection. AIM: To investigate the clinical features and clinical outcomes associated with OM development and severity in hematological cancer paediatric patients undergoing allo-HSCT who underwent professional dental care (PDC) and photobiomodulation (PBM) as prophylactic treatment. DESIGN: Medical data and OM presentation were retrieved retrospectively from all patients younger than 18 years who received allo-HSCT between 2013 and 2016. The incidence of OM was assessed and graded by two oral medicine specialists following the WHO guidelines, and it was correlated with clinical parameters. RESULTS: Forty-nine consecutive paediatric patients were included. OM was diagnosed in 73.5% of patients, and in 36.1% of patients, OM was classified as severe. Acute lymphoblastic leukemia as a primary diagnosis and the use of a myeloablative regimen were associated with OM development. The primary diagnosis and use of total body irradiation (TBI) were associated with aggressive OM. Neither the incidence nor the severity of OM affected the overall survival, whereas only the use of a myeloablative regimen and a high body mass index (BMI) were determinants of lower OM-free survival rates. CONCLUSIONS: A myeloablative conditioning and a high BMI were observed to be independent prognostic determinants of a lower OMFS rate. The cluster analysis allowed us to outline patient profiles with greater susceptibility to the development and severity of oral mucositis, which seems to be a useful tool to determine the risk of OM in paediatric patients.

Current knowledge regarding medication-related osteonecrosis of the jaw among different health professionals.

PURPOSE: To assess the current knowledge regarding medication-related osteonecrosis of the jaw (MRONJ); the adverse effects of anti-resorptive (AR) and anti-angiogenic (AA) drugs; strategies for MRONJ prevention and treatment; and perception of the dentist's role in assisting patients who use these drugs among physicians, dentists, and nurses. METHODS: Using questionnaires, the current knowledge of MRONJ was assessed among dentists, physicians, and nurses, who were divided into group I, which included specialties that directly assist cancer patients, and group II, which included other specialties. The questionnaires assessed the characteristics of the health professionals, training time, and specialties; their knowledge of AR and AA drugs; and their knowledge of MRONJ. RESULTS: A total of 1370 health professionals participated in the study, including 1032 dentists, 239 physicians, and 99 nurses. Among dentists and physicians, the training time (p = 0.036 and p < 0.001, respectively) and specialization in group I domains (p < 0.001 and p < 0.001, respectively) had a significant impact on MRONJ knowledge, while nurses showed no significant impact regardless of the training time and specialty. Less than 10% of the physicians and dentists could correlate the signs and symptoms of all stages of MRONJ. CONCLUSION: The findings indicated a notable lack of knowledge regarding MRONJ among dental surgeons and physicians, and especially among nurses. More experienced professionals and specialists in the areas that assist cancer patients usually have a greater understanding of the dentist's role in MRONJ prevention, diagnosis, treatment, and patient care and will introduce or are already using AR and AA drugs.

The impact of radiation caries in the quality of life of head and neck cancer patients.

PURPOSE: The objective of this multicentre study was to verify the relationship between the scores of quality of life (QoL) and the decayed, missing and filled teeth (DMFT) and radiation caries (RC) in patients treated with radiation therapy (RT) for head and neck cancer, and through this to determine if RC is capable of causing a significant decrease in the QoL. METHODS: One hundred patients were divided into 2 groups: patients with at least 1 year of RT completion who developed RC (study group, n = 50); and patients with at least 1 year of RT completion who did not develop RC (control group, n = 50). All patients answered the Brazilian-Portuguese version of the University of Washington quality of life (UW-QoL) questionnaire, which was divided into physical and social-emotional functioning domains and evaluated the DMFT index score. RESULTS: The mean score of QoL was 927.2 in the control group and 878.1 in the study group (P = 0.24). The mean score of DMFT was 30.5 in the study group and 20.7 in the control group (P = 0.001). The items recreation and saliva, which belong to the physical function domain, showed a statistically significant difference between the study and control groups (P = 0.031 and P = 0.047, respectively). Saliva was the item with the higher number of patient complaints in both groups. CONCLUSION: RC had a negative impact on the QoL of HNC patients.

Herpesviruses in the oral cavity of patients subjected to allogeneic hematopoietic stem cell transplantation and its relationship with oral mucositis.

OBJECTIVES: This study was performed to characterise oral shedding of herpesviruses in patients who underwent allogeneic hematopoietic stem cell transplantation (alloHSCT) and to investigate its relationship with oral mucositis (OM). MATERIALS AND METHODS: PCR and enzymatic digestion were conducted to identify oral shedding of herpesviruses and its correlation with OM development in 31 patients. The samples were collected at three sites in the oral cavity and at 5 times during follow-up; two additional collections were made from patients who developed ulcerative OM. RESULTS: HSV-1, EBV, CMV, HHV-6A, HHV-6B, and HHV-7 were detected in 4.97%, 16.02%, 4.41%, 2.20%, 3.31%, and 68% of the oral mucosal samples, respectively; 4.41%, 16.57%, 5.52%, 2.20%, 5.52%, and 63.53% of supragingival samples, respectively, and 4.41%, 18.23%, 2.76%, 1.65%, 2.75%, and 35.91% of subgingival samples, respectively. OM was diagnosed in 13 patients. The presence of HHV-7 in C1 (oral mucosa: p = 0.032) and C2 (supragingival: p = 0.009; subgingival: p = 0.002) was significantly increased in patients who developed OM, and patients exhibiting HHV-7 shedding in the oral cavity were 3.32-fold more likely to develop OM. CONCLUSIONS: Patients who developed OM showed higher HHV-7 shedding in the oral cavity at nadir (immediately prior to OM development), suggesting modifications to the inflammatory microenvironment. CLINICAL RELEVANCE: HHV-7 may be involved in oral dysbiosis in HSCT-related OM; enhanced understanding of its role in the pathogenesis of OM may lead to the development of strategies for managing and preventing this common side effect of alloHSCT.

Digital Workflow for Producing Oral Positioning Radiotherapy Stents for Head and Neck Cancer.

Oral positioning radiotherapy stents are devices that protect healthy structures adjacent to the target volume of head and neck radiotherapy treatment, leading to reduced acute and chronic side effects. This study describes a digital workflow to produce an oral positioning radiotherapy stent and analyze its efficacy by measuring dosimetric variations with and without this stent. An oral positioning radiotherapy stent was created according to a digital workflow that included intraoral scanning, digital design, and 3D printing for a patient with squamous cell carcinoma of the tongue. The patient underwent computed tomography to evaluate radiotherapy treatment by intensity-modulated radiation therapy with and without the use of the 3D-printed oral stent. The use of a 3D-printed oral positioning radiotherapy stent is a feasible and reproducible technique that reduced the planning target volume and radiation doses delivered to the hard palate, right parotid gland, and left parotid gland by 42%, 21%, and 8.5%, respectively.

Systematic review of photobiomodulation for the management of oral mucositis in cancer patients and clinical practice guidelines.

PURPOSE: To systematically review the literature and update the evidence-based clinical practice guidelines for the use of photobiomodulation (PBM), such as laser and other light therapies, for the prevention and/or treatment of oral mucositis (OM). METHODS: A systematic review was conducted by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society for Oral Oncology (MASCC/ISOO) using PubMed and Web of Science. We followed the MASCC methods for systematic review and guidelines development. The rigorously evaluated evidence for each intervention, in each cancer treatment setting, was assigned a level-of-evidence (LoE). Based on the LoE, one of the following guidelines was determined: Recommendation, Suggestion, or No Guideline Possible. RESULTS: Recommendations are made for the prevention of OM and related pain with PBM therapy in cancer patients treated with one of the following modalities: hematopoietic stem cell transplantation, head and neck (H&N) radiotherapy (without chemotherapy), and H&N radiotherapy with chemotherapy. For each of these modalities, we recommend 1-2 clinically effective protocols; the clinician should adhere to all parameters of the protocol selected. Due to inadequate evidence, currently, No Guideline Possible for treatment of established OM or for management of chemotherapy-related OM. The reported clinical settings were extremely variable, limiting data integration. CONCLUSIONS: The evidence supports the use of specific settings of PBM therapy for the prevention of OM in specific patient populations. Under these circumstances, PBM is recommended for the prevention of OM. The guidelines are subject to continuous update based on new published data.

Prognostic importance of FGF2 and FGFR1 expression for patients affected by ameloblastoma.

BACKGROUND: Fibroblast growth factor 2 (FGF2) and FGF receptor 1 (FGFR1) have been investigated in different human neoplasms and were shown to play important roles in the pathogenesis of these diseases; however, very few are known regarding their prognostic importance in the context of ameloblastoma. Therefore, the aim of this study was to investigate whether the expression of FGF2 and FGFR1 is associated with ameloblastoma clinical behavior. METHODS: Fifty-eight cases of ameloblastoma arranged in tissue microarray were submitted to immunohistochemistry against FGF2 and FGFR1. Clinicopathological parameters regarding sex, age, tumor size, duration and location, treatment, recurrences, radiographic features, cortical disruptions, and follow-up data were obtained from patients' medical records and correlated with the molecules expression. Univariate and multivariate Cox regression analyses were used to investigate the prognostic potential of the biomarkers. RESULTS: Forty-four cases (75.9%) exhibited cytoplasmic positivity for FGF2 in central and peripheral epithelial cells, 46 of 58 (79.3%) showed FGFR1 cytoplasmic positivity predominantly in the columnar peripheral cells, and 43 cases (74.1%) were positive for both. Expression of FGF2 and FGF2 + FGFR1 was associated with tumor recurrences (P = .05). However, univariate and multivariate analyses did not demonstrate a significant influence of FGF2, FGFR1, or FGF2 + FGFR1 in the 5-year disease-free survival (DFS) rate (P = .27, P = .33, and P = .25, respectively). CONCLUSION: Cytoplasmic expression of FGF2 and FGF2 + FGFR1 is associated with ameloblastoma recurrence, but FGF2 and FGFR1 are not determinants of a lower DFS.

Molecular basis of oral squamous cell carcinoma in young patients: Is it any different from older patients?

Oral squamous cell carcinoma (OSCC) is the commonest subtype of oral cancer, mainly affecting older patients. It used to be a rare disease among individuals younger than 40 years, but recently increased incidences in this age group are being reported worldwide. The pathogenesis of OSCC affecting young patients remains controversial, and the well-known etiological factors for oral cancer, tobacco, and alcohol use are believed to play a minor role in the carcinogenesis of the neoplasm, suggesting that the etiology and the molecular basis of OSCC may differ between younger and older patients. Although several molecular markers and chromosomal abnormalities have been demonstrated to differ between both groups, most of the studies have failed to find significant differences. Moreover, divergent results have also been obtained regarding the presence of high-risk human papillomavirus infection in OSCC of young patients. Given these contradictory results and the limited methodological approaches of the majority of the studies, the exact difference between both age groups remains to be fully established. In this review, we evaluate the available data to establish the current evidence that might support the hypothesis that the molecular basis of OSCC in young patients (especially those under 40 years) differ from the older patients.

Mismatch repair system proteins in oral benign and malignant lesions.

Different environmental agents may cause DNA mutations by disrupting its double-strand structure; however, even normal DNA polymerase function may synthesize mismatch nucleotide bases, occasionally demonstrating failure in its proofreading activity. To overcome this issue, mismatch repair (MMR) system, a group of proteins specialized in finding mispairing bases and small loops of insertion or deletion, works to avoid the occurrence of mutations that could ultimately lead to innumerous human diseases. In the last decades, the role of MMR proteins in oral carcinogenesis and in the development of other oral cavity neoplasms has grown, but their importance in the pathogenesis and their prognostic potential for patients affected by oral malignancies, especially oral squamous cell carcinoma (OSCC), remain unclear. Therefore, in this manuscript we aimed to review and critically discuss the currently available data on MMR proteins expression in oral potentially malignant lesions, in OSCC, and in other oral neoplasms to better understand their relevance in these lesions.

Extensive Oral Mucormycosis in a Transplanted Patient.

Mucormycosis is an invasive fungal disease caused by fungi from the Mucorales order that are found in the soil and decaying organic debris. Mucormycosis has been reported to be the third most common fungal disease in stem cell transplanted patients. The fungi have a tendency for vascular invasion, resulting in thrombi development, which decreases blood supply and leads to extensive tissue necrosis. Here, the authors present a patient of mucormycosis affecting the soft palate, oropharynx, and hypopharynx in a type II diabetic male patient who underwent allogeneic stem cell transplantation, and the authors further review the literature on oral mucormycosis for the last 10 years.

Effects of Different Radiation Doses on the Bond Strengths of Two Different Adhesive Systems to Enamel and Dentin.

PURPOSE: To evaluate the effects of three different radiation doses on the bond strengths of two different adhesive systems to enamel and dentin. MATERIALS AND METHODS: Eighty human third molars were randomly divided into four groups (n = 20) according to the radiation dose (control/no radiation, 20 Gy, 40 Gy, and 70 Gy). The teeth were sagittally sectioned into three slices: one mesial and one distal section containing enamel and one middle section containing dentin. The sections were then placed in the enamel and dentin groups, which were further divided into two subgroups (n = 10) according to the adhesive used. Three restorations were performed in each tooth (one per section) using Adper Single Bond 2 (3M ESPE) or Universal Single Bond (3M ESPE) adhesive system and Filtek Z350 XT (3M ESPE) resin composite and subjected to the microshear bond test. Data were analyzed using a two-way ANOVA followed by Tukey's test. Failure modes were examined under a stereoscopic loupe. RESULTS: Radiotherapy did not affect the bond strengths of the adhesives to either enamel or dentin. In dentin, the Universal Single Bond adhesive system showed higher bond strength values when compared with the Adper Single Bond adhesive system. More adhesive failures were observed in the enamel for all radiation doses and adhesives. CONCLUSION: Radiotherapy did not influence the bond strength to enamel or dentin, irrespective of the adhesive or radiation dose used.

The Effects of Ionizing Radiation on the Oral Cavity.

AIM: The aim of this study is to present a literature review on the effects of the ionizing radiation from radiotherapy treatment on dental tissues. BACKGROUND: Among the effects of increasing global life expectancy and longevity of the teeth in the oral cavity, increasing rates of neoplastic diseases have been observed. One of the important treatment modalities for head and neck neoplastic diseases is radiotherapy, which uses ionizing radiation as the main mechanism of action. Therefore, it is essential for dentists to be aware of the changes in oral and dental tissues caused by ionizing radiation, and to develop treatment and prevention strategies. RESULTS: In general, there is still controversy about the effects of ionizing radiation on dental structures. However, qualitative and quantitative changes in saliva and oral microbiota, presence of oral mucositis and radiation-related caries are expected, as they represent the well-known side effects of treatment with ionizing radiation. Points that still remain unclear are the effects of radiotherapy on enamel and dentin, and on their mechanisms of bonding to contemporary adhesive materials. CONCLUSION: Ionizing radiation has shown important interaction with organic tissues, since more deleterious effects have been shown on the oral mucosa, salivary glands and dentin, than on enamel. CLINICAL SIGNIFICANCE: With the increasing number of patients with cancer seeking dental treatment before and after head and neck radiotherapy, it is important for dentists to be aware of the effects of ionizing radiation on the oral cavity.

Immediate pain alleviation in oral mucositis and other oral ulcerative diseases through photobiomodulation therapy: the preemptive treatment concept.

OBJECTIVE: Photobiomodulation therapy is recommended by multiple international societies for managing oral mucositis. These recommendations are based on extensive evidence. However, the search for an optimal photobiomodulation protocol continues. This mapping review focuses on a novel aspect of photobiomodulation therapy which is the immediate effect on pain levels associated with oral ulcerative conditions. DATA SOURCES: This literature review systematically compiles and evaluates the evidence about oral mucositis, alongside other oral ulcerative conditions, as the protocols that achieved pain relief for these oral conditions may have potential applicability to oral mucositis management. The scientific database used was PubMed. CONCLUSION: Whereas most of the randomized controlled trials about photobiomodulation therapy for oral mucositis and other ulcerative oral diseases reported delayed pain relief, certain photobiomodulation therapy protocols reported immediate pain relief. The results of this review highlight the concept of preemptive photobiomodulation therapy, in which photobiomodulation therapy is delivered early in the development of oral mucositis throughout the oncotherapy and may achieve immediate pain relief consistently in most of the patients and close to a negligible pain level. Photobiomodulation therapy, as a powerful nonpharmacologic tool for immediate pain relief, has a great beneficial value in patients suffering from oral mucositis and other painful oral ulcerative diseases such as recurrent aphthous stomatitis and chronic graft-versus-host disease.

Guidance on mucositis assessment from the MASCC Mucositis Study Group and ISOO: an international Delphi study.

Background: Mucositis is a common and highly impactful side effect of conventional and emerging cancer therapy and thus the subject of intense investigation. Although common practice, mucositis assessment is heterogeneously adopted and poorly guided, impacting evidence synthesis and translation. The Multinational Association of Supportive Care in Cancer (MASCC) Mucositis Study Group (MSG) therefore aimed to establish expert recommendations for how existing mucositis assessment tools should be used, in clinical care and trials contexts, to improve the consistency of mucositis assessment. Methods: This study was conducted over two stages (January 2022-July 2023). The first phase involved a survey to MASCC-MSG members (January 2022-May 2022), capturing current practices, challenges and preferences. These then informed the second phase, in which a set of initial recommendations were prepared and refined using the Delphi method (February 2023-May 2023). Consensus was defined as agreement on a parameter by >80% of respondents. Findings: Seventy-two MASCC-MSG members completed the first phase of the study (37 females, 34 males, mainly oral care specialists). High variability was noted in the use of mucositis assessment tools, with a high reliance on clinician assessment compared to patient reported outcome measures (PROMs, 47% vs 3%, 37% used a combination). The World Health Organization (WHO) and Common Terminology Criteria for Adverse Events (CTCAE) scales were most commonly used to assess mucositis across multiple settings. Initial recommendations were reviewed by experienced MSG members and following two rounds of Delphi survey consensus was achieved in 91 of 100 recommendations. For example, in patients receiving chemotherapy, the recommended tool for clinician assessment in clinical practice is WHO for oral mucositis (89.5% consensus), and WHO or CTCAE for gastrointestinal mucositis (85.7% consensus). The recommended PROM in clinical trials is OMD/WQ for oral mucositis (93.3% consensus), and PRO-CTCAE for gastrointestinal mucositis (83.3% consensus). Interpretation: These new recommendations provide much needed guidance on mucositis assessment and may be applied in both clinical practice and research to streamline comparison and synthesis of global data sets, thus accelerating translation of new knowledge into clinical practice. Funding: No funding was received.

Photobiomodulation therapy in management of cancer therapy-induced side effects: WALT position paper 2022.

Disclaimer: This article is based on recommendations from the 12th WALT Congress, Nice, October 3-6, 2018, and a follow-up review of the existing data and the clinical observations of an international multidisciplinary panel of clinicians and researchers with expertise in the area of supportive care in cancer and/or PBM clinical application and dosimetry. This article is informational in nature. As with all clinical materials, this paper should be used with a clear understanding that continued research and practice could result in new insights and recommendations. The review reflects the collective opinion and, as such, does not necessarily represent the opinion of any individual author. In no event shall the authors be liable for any decision made or action taken in reliance on the proposed protocols. Objective: This position paper reviews the potential prophylactic and therapeutic effects of photobiomodulation (PBM) on side effects of cancer therapy, including chemotherapy (CT), radiation therapy (RT), and hematopoietic stem cell transplantation (HSCT). Background: There is a considerable body of evidence supporting the efficacy of PBM for preventing oral mucositis (OM) in patients undergoing RT for head and neck cancer (HNC), CT, or HSCT. This could enhance patients' quality of life, adherence to the prescribed cancer therapy, and treatment outcomes while reducing the cost of cancer care. Methods: A literature review on PBM effectiveness and dosimetry considerations for managing certain complications of cancer therapy were conducted. A systematic review was conducted when numerous randomized controlled trials were available. Results were presented and discussed at an international consensus meeting at the World Association of photobiomoduLation Therapy (WALT) meeting in 2018 that included world expert oncologists, radiation oncologists, oral oncologists, and oral medicine professionals, physicists, engineers, and oncology researchers. The potential mechanism of action of PBM and evidence of PBM efficacy through reported outcomes for individual indications were assessed. Results: There is a large body of evidence demonstrating the efficacy of PBM for preventing OM in certain cancer patient populations, as recently outlined by the Multinational Association for Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). Building on these, the WALT group outlines evidence and prescribed PBM treatment parameters for prophylactic and therapeutic use in supportive care for radiodermatitis, dysphagia, xerostomia, dysgeusia, trismus, mucosal and bone necrosis, lymphedema, hand-foot syndrome, alopecia, oral and dermatologic chronic graft-versus-host disease, voice/speech alterations, peripheral neuropathy, and late fibrosis amongst cancer survivors. Conclusions: There is robust evidence for using PBM to prevent and treat a broad range of complications in cancer care. Specific clinical practice guidelines or evidence-based expert consensus recommendations are provided. These recommendations are aimed at improving the clinical utilization of PBM therapy in supportive cancer care and promoting research in this field. It is anticipated these guidelines will be revised periodically.