However, the analysis of mRNA, mutation, methylation and prognosis of KCNQ4 shows that the expression of KCNQ4 is different in different tumor types, not only we have confirmed that KCNQ4 can affect the biological behavior of breast cancer cells, but also may affect other unexplored cancers, which needs to be verified by further molecular biology and clinical experiments. This evidence concerns the gene KCNQ4 and cancer.