For example, circEHMT1, which we identified as a risk factor in NSCLC, has been shown in breast cancer studies to inhibit cancer cell metastasis by reducing MMP2 levels through the circEHMT1/miR-1233-3p/KLF4 axis.52 In breast cancer, this mechanism is thought to contribute to a more favorable prognosis by controlling metastatic spread. This evidence concerns the gene MMP2 and non-small cell lung carcinoma.