ERBB2 and neoplasm: In infiltrating ductal carcinoma, bone metastases were more common in patients with human epidermal growth factor 2 (HER2) positive tumors (4.9% vs 2.7%), higher tumor grade (4.1% for grade III, 3.1% for grade II and 1.0% for grade I), tumor stage T3-4 compared to stage T0-2 (15.8% vs 1.4%) and N2-3 (10.6%) compared to N1 (6.0%) and N0 (0.9%) (all p < 0.001).