Neo-adjuvant endocrine therapy was more likely for patients diagnosed during transition with a stage I, stage II, HR+/HER2+, or HR+/HER2− tumor (OR 5.10, 95%CI 3.13–8.29; OR 3.09, 95%CI 2.30–4.14; OR 2.56, 95%CI 1.11–5.89; OR 3.10, 95%CI 2.44–3.94, respectively), or during lockdown with a stage I, stage III, HR+/HER2+, or HR+/HER2− tumor (OR 5.05, 95%CI 2.95–9.86; OR 2.44, 95%CI 1.26–4.72; OR 3.54, 95%CI 1.64–7.60; OR 1.65, 95%CI 1.15–2.37, respectively). The gene discussed is ERBB2; the disease is neoplasm.