ERCC4 and head and neck squamous cell carcinoma: The XPC c.2815A>C [14–17], XPD c.934G>A and c.2251A>C [8–10, 13, 14, 19, 20, 24, 26, 28], XPF c.2505T>C [26], and ERCC1 c.354C>T [10–12, 15, 16, 18, 21, 25, 26, 28] SNPs were associated with variable response rate (RR), toxicity, progression-free survival (PFS) and overall survival (OS) in patients with different tumors treated with CDDP-based chemotherapy with or without RT; however only few studies were conducted in HNSCC patients [24, 25].