Is There an Interplay between Oral Microbiome, Head and Neck Carcinoma and Radiation-Induced Oral Mucositis?

Abstract

Head and neck carcinoma is one of the most common human malignancy types and it ranks as the sixth most common cancer worldwide. Nowadays, a great potential of microbiome research is observed in oncology—investigating the effect of oral microbiome in oncogenesis, occurrence of treatment side effects and response to anticancer therapies. The microbiome is a unique collection of microorganisms and their genetic material, interactions and products residing within the mucous membranes. The aim of this paper is to summarize current research on the oral microbiome and its impact on the development of head and neck cancer and radiation-induced oral mucositis. Human microbiome might determine an oncogenic effect by, among other things, inducing chronic inflammatory response, instigating cellular antiapoptotic signals, modulation of anticancer immunity or influencing xenobiotic metabolism. Influence of oral microbiome on radiation-induced oral mucositis is expressed by the production of additional inflammatory cytokines and facilitates progression and aggravation of mucositis. Exacerbated acute radiation reaction and bacterial superinfections lead to the deterioration of the patient’s condition and worsening of the quality of life. Simultaneously, positive effects of probiotics on the course of radiation-induced oral mucositis have been observed. Understanding the impact on the emerging acute radiation reaction on the composition of the microflora can be helpful in developing a multifactorial model to forecast the course of radiation-induced oral mucositis. Investigating these processes will allow us to create optimized and personalized preventive measures and treatment aimed at their formation mechanism. Further studies are needed to better establish the structure of the oral microbiome as well as the dynamics of its changes before and after therapy. It will help to expand the understanding of the biological function of commensal and pathogenic oral microbiota in HNC carcinogenesis and the development of radiation-induced 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

“…Bacterial colonization of OM ulcerations prolongs lesion resolution by provoking the inflammatory response [ 50 ]. Speciation studies have suggested that a range of dysbiotic changes impact the progression and severity of mucositis [ 51 ], and that individual variations in the microbiome composition may be associated with variations in OM trajectory.…”

The influence of antibiotic administration on the outcomes of head-and-neck squamous cell carcinoma patients undergoing definitive (chemo)radiation

“…Especially the efficacy and toxicity profile of immune checkpoint inhibitors have been shown to depend on the patients’ gut microbiome [ 13 ]. There is also a rising number of studies reporting potential interactions between the microbiome and radiotherapy [ 14 , 15 ]. For instance, germ-free mice have been demonstrated to exhibit a more radioresistant intestinal mucosa, and therapeutic manipulations of the microbiome, e.g., by fecal microbiome transplantation or administration of distinct bacteria, influenced radiotherapy-related toxicities [ 16 , 17 ].…”

Correlations between the severity of radiation‐induced oral mucositis and salivary epidermal growth factor as well as inflammatory cytokines in patients with head and neck cancer

“…The pathobiology of mucositis contains a complex cascade of biologic processes where pro‐inflammatory cytokines, reactive oxygen species, second messengers, and the oral microbiome lead to the oral mucosa injury 12 . Effects of oral microbiome on RIOM are presented by the production of additional inflammatory cytokines, and also facilitates mucositis progression and aggravation 1 . It is demonstrated that the release of inflammatory transmitters plays a key role in RIOM occurrence and development 13 .…”

“…Head and neck cancer (HNC) is a frequent human malignancy, ranking as the sixth most common cancer around the world. 1 This disease contains lip and oral cavity, larynx, nasopharynx, oropharynx, and hypopharynx cancers. 2 The therapeutic strategies for HNC includes surgery, chemotherapy, and radiation therapy (RT), alone or in combination, and these treatments could lead to acute and chronic changes of the oral cavity, ranging from hard tissues (teeth and alveolar bone) and oral mucous membrane, to soft tissues of the head and neck.…”