In our previous study, through large-scale analyses of RNA-seq data from The Cancer Genome Atlas, we identified recurrent gene rearrangements between ESR1 and its neighboring gene, coiled-coil domain containing 170 (CCDC170), in 6–8% of luminal B breast cancer, the majority of which are likely the result of tandem duplications [13]. Here, CCDC170 is linked to breast cancer.