Breast tumor excision in the setting of metastatic disease was performed in five (three HR+/HER2−, one HR+/HER2+, and one HR−/HER2+) patients before any systemic treatment for MBC (i.e., upfront primary tumor resection) in four (one HR+/HER2−, one HR+/HER2+, one HR−/HER2+, and one TNBC) patients who had metastatic disease controlled with the first-line systemic therapy, and in one patient with HR−/HER2-unknown MBC who had a primary tumor that was refractory to two lines of systemic therapy. This evidence concerns the gene ERBB2 and metastatic neoplasm.