Except for human papillomavirus(HPV)-associated oropharyngeal cancer, immunological biomarkers do not influence treatment algorithms in locally advanced head and neck cancer. In the meantime, a prognostic significance of tumor infiltrating lymphocytes has been recognized. However, these biomarkers do not influence clinical decisions. This may be due to previous focus on the entire group of heterogeneous squamous cell carcinomas in the head and neck region, while the tumor localization has been neglected. In addition, the isolated observation of singular immune cell populations may not be sufficient with regard to the complex interactions of the tumor with the local and systemic immune system, e.g. the presence of regulatory T cells (FoxP3+) in immunologically highly active tumors ("inflamed" or "hot") improves the prognosis, whereas the prognosis is worsened in immunologically less active tumors ("immune desert").The immune checkpoint molecule programmed death-ligand 1 (PD-L1) is currently used as a single predictive marker for immunotherapy with PD(L)-1 inhibitors. Certainly, combined prospective analyses of immune cells and immune checkpoint molecules in large patient cohorts are scarce so far. Of note, the prognostic relevance of immune cells and immunologically active substances in the peripheral blood serving as makers for immunotherapies has already been described. Yet prognostic and predictive markers in the peripheral blood have rarely been studied or linked to the local tumor immune status. However, analyses of single biomarkers of local and systemic immune responses and different immune cell populations can be expected to gain prognostic precision through cluster formation and allow grouping of head and neck tumors according to immunobiological criteria rather than anatomic localization. Therefore, the investigators expect to be able to identify an immunobiological biomarker signature for head and neck tumors that will contribute to the development of future individualized treatment approaches leading to precision head and neck oncology.
