ESR1 and neoplasm: We recently reported that the estrogen receptor (ER) negative basal-like and claudin-low tumor subtypes are likely to spread to vital organs such as the brain and lung; without targeted therapies, HER2-enriched tumors aggressively colonize the liver, while ER+/luminal A and luminal B tumors are slower to disseminate and are usually first identified in the bone [9].