ERCC2 and colorectal carcinoma: A large number of epidemiological studies have been carried out recently to understand the effects and role of XPD SNPs on the modulation of risk of CRC; while some studies found a significant association between the two (Skjelbred et al., 2006; Gan et al., 2012; Huang et al., 2013; Procopciuc and Osian, 2013; Rezaei et al., 2013; Paszkowska-Szczur et al., 2015) others failed to link them (Yeh et al., 2005; Zhang et al., 2011, 2014; Du et al., 2014; Moghtit et al., 2014).