ERBB2 and metastatic neoplasm: The multivariable analysis adjusted for age, visceral metastases, number of metastases, de novo metastatic disease, period of care, and hormone receptor status confirmed that patients with ERBB2-low MBC had an independently better OS compared with patients with ERBB2-zero MBC (adjusted hazard ratio [HR], 0.95; 95% CI, 0.91-0.99; P = .02).