Recognizing and reversing the immunosuppressive tumor microenvironment of head and neck cancer.

The estimated annual incidence of oral cavity and pharyngeal cancer is 39,000 in the United States and 260,000 cases worldwide. Despite significant advances in surgery, chemotherapy and radiotherapy, the 5-year survival rate for locally advanced head and neck tumors remains at 50 %. With further intensification of existing treatment limited by the already significant morbidity of multi-modality treatment, there is a clear need for novel therapeutic strategies [1]. Accumulating evidence suggests that the tumor microenvironment of head and neck squamous cell carcinoma (HNSCC) is highly immunosuppressive, mediated by soluble and cell-associated inhibitory mediators and recruitment of host immunosuppressive cells. Thus, understanding and reversing the specific mechanisms underlying tumor-mediated immunosuppression in HNSCC is an important approach to generating an effective antitumor immune response, either as a component of immune-based therapy or as a complement to conventional treatment approaches. This article outlines significant immune-suppressive mechanisms in the HNSCC tumor microenvironment and potential approaches to enhancing the antitumor immune response.