The paper concluded the results of the interactions of twenty-five microRNAs with FOXO3a in malignant tumours such as breast, liver, gastric, colorectal, and prostate cancers: There were dual microRNAs synergizing with FOXO3a to restrain the growth of breast cancer cells miR-29b, miR-338, and miR-34b, miR-34c; and a single microRNA synergizing with FOXO3a to suppress hepatocellular carcinoma cells, such as miR-30b-5p, miR-124-3p.1, and miR-498 (Figure 3A), the tumour suppressor function of these microRNAs makes it possible to be the target of drugs for cancer therapy. This evidence concerns the gene FOXO3 and breast cancer.