XRCC2 and colorectal cancer: In recent years, studies on XRCC2 focuses on HR repair mechanisms and the relationship between XRCC2 gene polymorphism and tumor susceptibility [10–14], such as the relationship between XRCC2 R188H polymorphism and breast cancer, thyroid cancer, ovarian cancer, etc. Reports on XRCC2 associated with colorectal cancer only deal with XRCC2 polymorphism [15–19].