MTHFR and carcinoma: Among the DNA repair-related genes, the SNP rs1051772 of topoisomerase DNA binding II binding protein 1 (TOPBP1) gene was found to be associated with a decreased risk of RP in NSCLC patients through DNA replication checkpoint control and genomic stability maintenance [102,143], and SNP rs1801131 of the methylenetetrahydrofolate reductase (MTHFR) gene was reported to be statistically correlated with grade ≥2 RP among esophageal squamous cell carcinoma patients in the Chinese Han population [103].