ESR1 and metastatic malignant neoplasm in the lymph nodes: The different pCR rate between our current investigation and the NSABP B27 may have been due to the greater number of lymph node metastases [247/247 (100%) vs. 244/805 (30.3%)] and also the higher ER positivity [167/247 (67.6%) vs. 319/805 (39.6%) in Neo-Shorter vs. NSABP-B27].