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