The Clinical Relevance of Immune Cells and CTC in HNSCC Patients

Head and neck squamous cell carcinomas (HNSCCs) are mainly caused by tobacco, alcohol consumption and betel nut chewing and the sixth most common cancer in the world. Despite significant advances in the treatment modalities involving surgery, radiotherapy, and concomitant chemoradiotherapy, the 5-year survival rate remained below 50% for the past 30 years. The worse prognosis of these cancers must certainly be linked to the fact that HNSCCs strongly influence the host immune system. During this process, mesenchymal tumor-like cells are highly mobile and enter quickly adjacent structure (intravasation), from where they travel through lymphatic and blood vessels as circulating tumor cells (CTC), which are single cells with malignant potential detected in the peripheral bloodstream and essential for establishing metastasis. Programmed death 1 (PD-1) and its ligand (PD-L1) play pivotal roles in regulating host immune responses. Substantial evidence has demonstrated that PD-L1 can deliver an inhibitory signal to PD-1 expressing T cells, leading to suppression of the immune response by inducing apoptosis, energy, unresponsiveness and functional exhaustion of T cells. However, the inhibitory effects of this pathway on the function of cytotoxic T lymphocytes, the main effector cells in HNSCC patients, are not well defined. In this study aims to solve two main problems: one is to improve and try to optimize current protocols of CTC isolations based on the investigator previous work, which is one of most challenging problems in CTC field to date; the other is to understand the status of immune system in HNSCC patients, especially focusing on PD-1-PD-L1 pathway and its expressions. After series basic experiments of immune cell analysis and conditional adjustment of CTC isolation protocols, the investigator are willing to isolate CTCs and immune cells at a single blood drawing at the same time. A prospective trial will be conducted to elucidate the roles of PD-1 expression l