Evidence demonstrated that HER2+ breast cancer patients with low expression of miR-222-3p showed complete response (31 out of 65 patients, 4.69%) (OR = 0.258, 95% CI (0.070–0.958, p = 0.043)), disease-free survival (HR = 5.778, 95% CI (1.196–27.906), p = 0.029) and overall survival (p = 0.0037) [253]. This evidence concerns the gene ERBB2 and breast cancer.