In two recent studies, performed by the group of Brackenbury and ours, it was clearly demonstrated that the expression of NaV1.5 in human breast cancer cells is critical for the metastatic colonization of lungs of immunodepressed mice, and that inhibitors of NaV1.5 that are approved by the Food and Drug Administration (FDA), such as ranolazine for the treatment of chronic angina, or phenytoin as an anticonvulsant, significantly reduced metastatic organ colonization by NaV1.5-expressing human breast cancer cells (Driffort et al., 2014; Nelson et al., 2015). This evidence concerns the gene SCN5A and breast cancer.