If considered an independent cancer type, ILC would be the sixth-most-common cancer in women, with an occurrence frequency similar to those of non-Hodgkin's lymphoma and melanoma.[4,5] ILC tumors typically have a good prognosis, low histology grade, and positivity for the estrogen receptor; however, they can be strongly metastatic and are the main cause of cancer deaths among women in many countries worldwide.[2,6] There is increasing evidence that ILC is clinically unique, and that its early diagnosis and prognosis are especially important. Here, ESR1 is linked to cancer.