In a study of genomic profiling of 249 (134 ER-positive and 115 ER-negative) tumor specimens from 208 patients, Jeselsohn and colleagues carried out DNA sequencing of 3,230 exons of 182 cancer-related genes and 37 introns of 14 commonly fused genes, including in 37 pairs of matched primary and metastatic breast tumors [30]. This evidence concerns the gene ESR1 and cancer.