In 6 patients (S-26, S-27, S-28, S-31, S-51, and S-60), tumor and metastasis tissues were available among samples initially analyzed for the mutational status of ESR1. Four of these patients (S-26, S-27, S-28, and S-60) did not show any ESR1 mutation, while the remaining 2 patients (S-31 and S-51) showed mutations in samples derived from metastases. This evidence concerns the gene ESR1 and neoplasm.