BACKGROUND: Single nucleotide polymorphisms (SNPs) are associated with various diseases, including gastric cancer. The ADAMTS14 gene is linked to multiple types of cancer. However, the relationship between ADAMTS14 and its genetic polymorphisms with susceptibility to gastric cancer (GC) and prognosis remains unclear. METHODS: A case-control study was conducted involving 855 patients diagnosed with gastric cancer (GC) and an equal number of cancer-free controls. Following rigorous statistical analysis, molecular experiments were performed to elucidate the functional significance of the SNPs in the context of GC. RESULTS: ADAMTS14 rs3740440 (OR = 1.45, p = 0.014) shows a significant association with increased GC risk, while rs11572 (OR = 0.42, p <
0.001) is associated with protection against GC. Moreover, patients with the (CG + GG) genotype of rs3740440 exhibit a poor prognosis (HR = 1.68, p = 0.007). Mechanistically, luciferase reporter assays revealed that the G allele of rs3740440 disrupts the binding of hsa-miR-4294 and hsa-miR-3198 to the 3' untranslated region (3' UTR) of ADAMTS14, leading to increased expression of ADAMTS14 and the promotion of malignant behaviors in GC cells. CONCLUSIONS: Our findings underscore the significant role of ADAMTS14 SNPs in both the risk and prognosis of gastric cancer (GC), providing valuable insights into the underlying molecular mechanisms. Specifically, rs3740440 disrupts the interaction between ADAMTS14 and miRNA, resulting in increased expression of ADAMTS14. This heightened expression enhances its malignant biologic behaviors, indicating that rs3740440 could be a potential predictive marker for gastric cancer risk and prognosis.