ERBB2 and neoplasm: Compared to patients with non-metastatic tumors, patients with tumor metastasis showed a higher CTC enumeration (5 vs. 2, p < 0.001), larger tumor size (2.5 vs. 2.0, p = 0.007), more axillary lymph node metastasis (2 vs. 0, p = 0.01), and higher HER2-positive status (56.1% vs. 34.7%, p = 0.042).