ESR1 and neoplasm: However, in a multivariable Cox proportional hazards model adjusting for tumor size, number of positive nodes, ER/PR status, and local therapy received, patients with HER2-low status had worse DFS than those with HER2-negative tumors (HR 2.0, 95% CI 1.0–4.1, p = 0.05) (Table 2).