The BRENDA-Index was calculated using the following formula: BRENDA-Index = 5 ∗ luminal B-HER2-negative like + 4 ∗ luminal B-HER2-positive like +7 ∗ HER2-overexpressing + 8 ∗ triple-negative + 5 ∗ tumour size 2 + 9 ∗ tumour size 3/4 + 4 ∗ grading 2 + 6 ∗ grading 3 + 8 ∗ nodal status (1 ≤ n ≤ 3) + 15 ∗ nodal status (n > 3). The gene discussed is ERBB2; the disease is neoplasm.