Role of Surgical Pathologist for Detection of Immunooncologic Predictive Factors in Head and Neck Cancer

Immunotherapy has shown promising results in the treatment of recurrent and metastatic head and neck cancers. Antiprogrammed cell death (PD)-1 therapies have been recently approved in this setting and they are currently tested also in the treatment of locally advanced diseases and in the neoadjuvant setting. However, the clinical benefits of these treatments have been quite variable, hence the need to select those patients who may obtain the maximal efficacy through the identification of predictive biomarkers. Currently, PD-L1 immunohistochemical expression by tumor and immune cells is the most widely used predictive biomarker for immunotherapy in head and neck squamous cell carcinoma. Nevertheless, patients with PD-L1 − tumors may still respond to treatments, thereby emphasizing the need for the identification of other predictive biomarkers. In this review, we summarize the current data on histologic and molecular parameters that can be used to select patients with head and neck cancers for immunotherapy, with a focus on squamous cell carcinoma and salivary gland carcinomas.