XRCC1 and colorectal cancer: Currently, there is increasing evidence that gene analysis reveals the importance of DNA repair genes and that polymorphisms, such as the XRCC1 polymorphisms R399Q and R280H, are associated with different human cancers, such as bladder cancer, breast cancer, colorectal cancer, lung cancer, and endometrial carcinoma16, 33, 34, 35, 36.