Of the 6,234 patients diagnosed with stage IV HR+/HER2+ breast cancer, the majority were 50 years or older (n = 4602 [73.8%]), female (n = 6141 [98.5%]), white (n = 4491 [72.0%]), had grade 3/grade 4 disease (n = 2912 [46.7%]), visceral involvement (n = 3276 [52.6%]), 1 metastatic site (n = 4003 [64.2%]), and reported no comorbidities (n = 5161 [82.8%]). This evidence concerns the gene ERBB2 and breast cancer.