PGC and gastric cancer: An interaction effect of pri-let-7a-1 rs10739971 polymorphism with ERCC6 rs1917799 polymorphism was observed for the risk of gastric cancer (Pinteraction = 0.026); and interaction effects of pri-let-7a-1 rs10739971 polymorphism with PGC rs6458238 polymorphism (Pinteraction = 0.012) and PGC rs9471643 polymorphism (Pinteraction = 0.039) were observed for the risk of atrophic gastritis.