To provide a comprehensive account of the association of MMP-9 gene polymorphisms (rs3918242) with susceptibility to cancer. A literature search for eligible candidate gene studies published before May 27, 2022 was conducted in PubMed, Medline, Google Scholar and Web of Science. Potential sources of heterogeneity were sought out across subgroups and sensitivity analysis. Publication bias were also estimated. Overall, a total of 37 articles with 7616 cases and 8165 controls for rs3918242 gene polymorphisms were enrolled. Our meta-analysis suggests that MMP-9 rs3918242 might be associated with breast cancer and gastric cancer susceptibility, and perhaps reduce the risk of lung cancer.