ESR1 and neoplasm: The NCCN Practice Guidelines 2007 http://www.nccn.org recommended adjuvant chemotherapy only in tumours between 6 mm and 10 mm without metastases in lymph nodes (pT1b pN0): in ER-negative pT1b pN0 (both HER2-negative and HER2-positive) and, in addition to hormonal therapy, in ER positive pT1b pN0 moderate/poorly differentiated or with unfavourable features (both HER2-negative and HER2-positive).