Although prognostication through GS has been prospectively validated and is recommended by contemporary guidelines in ER‐positive, HER2‐negative (ER+/HER2−) BC (Cardoso et al., 2019), there is still risk for undertreatment, especially in patients with node‐positive disease (Matikas et al., 2019a). The gene discussed is ERBB2; the disease is breast cancer.