Head and neck squamous cell carcinoma (HNSCC) is the 4th highest incidence of cancer and 6th of cancer death of the males in Taiwan. Because the patients were mainly middle-aged male, the disease eventually resulted in a huge loss of labor force, productivity and a huge burden of family supports and medicinal costs. Unfortunately, the incidence and death of HNSCC seemed to be increasing in Taiwan. Currently, the primary treatments of HNSCC are mainly surgery, radiotherapy, chemotherapy or targeted therapy or concurrent chemoradiotherapy. Immune checkpoint inhibitors become an emerging treatment in recent days. However, how to select adequate patient by using biomarkers remains an unsolved problem. Therefore, investigator have developed a new method for isolation and detection of circulating tumor cells (CTCs) in HNSCC patients. Moreover, the expression of immune markers (such as PD-L1, PD-L2, PD-1) on CTCs or immune cells might be a good target to study. Investigator's preliminary data found CTCs and circulating cancer stem-like cells but not PD-1 expression levels on peripheral T cells in patients with recurrence or metastasis HNSCC did not associated with overall survival. Therefore, investigators are wondering if PD-L1 more specific due to it expression on cancer cells. Therefore, in the 3-year project, investigators will utilize developing device and protocol in first year and then enroll 40 freshly diagnosed participants with head and neck cancer at stage III-IV with intent to receive curative concurrent chemo-radiotherapy (CCRT), and then analyze CTCs, PD-L1 expression levels on CTCs. Blood sample will be taken before, during (definition: 3-6 weeks after start RT) and after (definition: 4 +/-2 weeks after complete CCRT) completion of CCRT. Investigators will also enroll 10 health participants and taking blood sample for 3 times and follow up. Further statistical tests with clinical conditions (disease status, treatment effects, progression or distant metastasis and death) will be performed to elucidate their clinical significance. Hopefully, investigators will clarify the correlation between clinical outcomes and expression of PD-L1 on CTCs in head and neck patients. This could be a new biomarker for clinical cancer care.

Inclusion Criteria:

• Patients with head and neck squamous cell carcinoma with age at diagnosis ≥ 20 years
• Stage III-IV according to AJCC 8th ed.
• Intent to receive curative concurrent chemoradiotherapy (CCRT)
• 10 healthy donors without any cancer diagnosis within 5 years

Exclusion Criteria:

• P16 positive oropharyngeal cancer
• Non-Platinum based CCRT
• Previous diagnosed with cancer within 3 years
• Synchronous cancer
• Poor compliance, cannot cooperate for blood sampling for CTCs isolation as time schedule or clinical treatment or follow-up

Stage III-IV head and neck squamous cell carcinoma patients, except those with P16 positive oropharyngeal cancer patients, who are going to do curative platinum-based CCRT.