ERBB2 and Langer mesomelic dysplasia: Patients with endocrine-sensitive disease at the time of BrM diagnosis had a longer brain-specific progression-free survival (7 mo versus 5 months, <i>P</i> = .004) and overall survival (24 months versus 5 mo, <i>P</i>  = .002) compared with those with endocrine resistance.<h4>Conclusions</h4>Most patients with HR+/HER2- BrM have endocrine-resistant disease, with an unexpectedly high likelihood of developing LMD.