PROS1 and xeroderma pigmentosum group D: We investigated the role of DNA repair proteins breast cancer susceptibility 2 (BRCA2), xeroderma pigmentosum group D (XPD) and apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) in determining the risk for head and neck squamous cell cancer (HNSCC) in a case-control study from North-East India.