In keeping with the higher prevalence of HER2 negativity in the SLNB+ group, HER2-negative tumours had approximately 5.5-fold higher odds of SLNB positivity compared with HER2-positive tumours (OR 5.50, 95% CI 1.50–20.14; p = 0.010). The gene discussed is ERBB2; the disease is neoplasm.