Changes in oral, skin and gut microbiome mediated by radiotherapy and their potential roles in the prognosis of radiotherapy‑induced Dermatitis and oral mucositis: Cohort study

Despite the essential role of RT in HNC treatment, side effects such as Radio induced dermatitis and mucositis are frequent and have a great impact on patient’s quality of life and adherence to RT treatments, thereby affecting clinical outcomes (1-3). Evidence that these side effects are associated with microbiome changes has been accumulating for skin (4), oral (5) and intestinal microbiome (6,7). The mechanisms and impact of the microbiome changes in RT have not been fully described and are not fully understood. Several skin conditions are associated with a dysbiosis of skin microbiota including wound healing (8,9). Nevertheless, in some cases is difficult to determine whether the altered skin microbiota is a cause or consequence of the skin disorder.
On the other hand, the intestinal tract harbor’s a diverse collection of bacteria, fungi, and protozoa, and the most known gut microbiota (10). Many of these microorganisms are essential for metabolic and immune function. An imbalance diet or other external factors that leads to gut microbiota dysbiosis, also affects intestinal permeability and disturbance of immune systems by production of inflammatory molecules (11-16).
The study of the microbiome in HNC as an explanatory mechanism and potential therapeutic avenue for overcoming the limitation of locoregional toxicity and response of RT has gained significant interest in recent years. In fact, understanding how and why the microbiome is modified in response to RT has led to the emergence of probiotics and fecal microbial transplantation used to recreate an appropriate balance of pro-and anti-inflammatory cells with aims of enhancing response to RT and minimizing toxicity. This has been explored for the gut microbiome (6,17) but not for the oral microbiome. Adding that Radiotherapy was accompanied by significant reduction in microbial diversity of salivary microbiome (18).
Understanding how Metabolic abilities of skin, oral and Gut microbiome could support their potential roles in the pathogenesis of RIDM. RadBiome Study involving 30 patients with HNC with RT as therapeutical intervention for 12 weeks (appendix 1). Patients that meet the inclusion and exclusion criteria (appendix 2), will be enrolled one week before the first RT and one month after the last session (6/7 weeks). Assessment occurs at baseline, 1 week before exposition, first day exposition, weekly until 8 week and 12 Week after first day of exposure. Assessments include self-collected fecal samples, skin and oral swab samples. Anthropometrics, RTOG Scale, thermography, blood pressure, metabolic parameters, Dietary intake, pain, comfort and psychological state will be assessed using validated self-report questionnaires. The disturbance of immune systems by production of inflammatory molecules will be accessed by Luminex xMAP based Multiplex technology.