NOD2 and cancer: Four studies consisting of 368 cases and 567 controls investigated the association of NOD2 rs2066842 C/T (P268S) polymorphism and cancer risk; 16 studies including 4507 cases and 4780 controls studied the association of NOD2 rs2066844 C/T (R702W) polymorphism and cancer risk; 14 articles including 4185 cases and 4474 controls investigated the association of NOD2 rs2066845 C/G (G908R) polymorphism and cancer risk; for NOD2 rs2066847/rs5743293 (3020insC) polymorphism, 25 studies consisting of 23167 cases and 28601 controls were included.