ATM and head and neck squamous cell carcinoma: This is also the first report demonstrating the association of MRE11 rs2155209, XRCC5 rs828907, LIG4 rs1805388, ATM rs1801516 and RAD51 rs12593359 with survival in HNSCC, as well as the first to indicate that CHEK1 rs558351 may play a role in cancer disease.