This is an open access book. With a wealth of exciting data emerging in this rapidly evolving field, this book reviews state-of-the-art knowledge with emphasis on multidisciplinary decision making and management of head and neck cancer. Significant detail is provided on a wide range of topics including:   oral potentially malignant disorders, cell-based assays for drug discovery and drug evaluation, the role of precision medicine (genomics and beyond), innovations in systemic therapy (including metronomic chemotherapy and immunotherapy), surgery (including partial laryngeal surgery and quality of reconstruction) and radiotherapy (including FLASH-therapy) in different disease settings taking into account their impact on benefit/risk ratio. In addition, specific topics such as hypoxia, hyperthermia, intratumoral drug administration, noninvasive biomarkers, local therapy in metastatic head and neck cancer, sentinel lymph node biopsy in cN0 early-stage oral cavity cancer, prognostic factors in HPV-positive oropharyngeal cancer, molecular characterization of salivary gland cancer (including implications for treatment) and strategies to improve outcome in salivary duct carcinoma are discussed. All disciplines involved in the treatment of head and neck cancer are covered with a focus on translation into daily practice. The 9 th -THNO is designed for medical oncologists, head and neck surgeons, radiation oncologists, otolaryngologists, and other medical professionals involved in the treatment and care of patients with head and neck cancer.