Microbiota-guided Radiotherapy for Head and Neck Cancer

Head and neck cancer (HNC) is the sixth most common cancer worldwide. Therapeutic outcomes for HNC remain unsatisfactory and heterogeneous, with 5-year survival rates ranging from 28% to 67% overall. Moreover, HNC patients experience side effects during treatment, including inflammation and ulceration of the oral mucosa caused by radiation or cytotoxic agents (oral mucositis), which represents a limiting factor for both the escalation of radiotherapy dosage and the duration of treatment. Several observational studies have highlighted statistical associations between the oral microbiota and numerous factors related to HNC and its therapeutic course. The working hypothesis of this study is that it is possible to establish causal relationships between the functional traits of the human oral microbiota and the effectiveness of radiotherapy in HNC treatment, directly from the analysis of data collected in observational cohorts, by leveraging the statistical framework of causal inference. The oral microbiota of HNC patients enrolled in the study will be characterised through metagenomic sequencing of saliva samples collected from each patient, at radiotherapy-baseline, at 2 weeks from radiotherapy start and at radiotherapy end. Main Objectives of the Study: * Creation of a dataset of the oral microbiota in HNC patients, including both bacterial and viral components, as well as data linked to treatment effectiveness and side effects. * Estimation of the causal effect of the functional traits of the oral microbiota on the modulation of radiotherapy in HNC. * Development of predictive models for local tumour control and for oral mucositis, based on the oral microbiota of HNC patients. Clinical Relevance: The causal relationships inferred between the functional/metabolic traits of the microbiota and radiotherapy effectiveness will help build interpretable predictive models and reveal strategies to reprogram the microbiota functionality of patients with head and neck cancer. This will increase the likelihood of tumour eradication or control while reducing the risk of radiation-induced side effects.