ERBB2 and breast cancer: At the 1.5-year landmark analysis, patients treated with anti-HER2 therapy exhibited a heightened risk of developing osteoporosis relative to those treated without anti-HER2 therapy in the groups with age at breast cancer diagnosis of <50 and 50–59 years (HR, 1.23; 95% CI, 1.15–1.31 and HR, 1.22; 95% CI, 1.15–1.29, respectively).