Within the context of ER-/lymph-node-negative (LN-) disease, the NSABP-B13, B-19, and B-23 trials highlighted the non-inferiority of prescribing four cycles of doxorubicin and cyclophosphamide (AC) versus six cycles of CMF chemotherapeutical agents or methotrexate and 5-fluorouracil (MF), while also highlighting no benefit of adding tamoxifen (a selective estrogen receptor modulator) for this disease subtype [22,23,24]. Here, ESR1 is linked to glycogen storage disease VI.