The efficacy of anthracycline‐ and taxane‐based chemotherapy for perioperative treatment of breast cancer (BC) has been established. No superiority of a cytotoxic regimen has been demonstrated, provided that administration of an anthracycline and a taxane is warranted. The ASTER study was designed to investigate the safety of 6 months of perioperative chemotherapy with Doxorubicin and Paclitaxel, followed by Cyclophosphamide, Methotrexate, and 5‐Fluorouracil. ASTER enrolled patients with cT2‐3 N0‐1 or pT1‐2 N1‐3 BC, from November 2008 to August 2011. Treatment consisted of Doxorubicin 60 mg/sm, Paclitaxel 200 mg/sm q21 (AT) for three cycles followed by Cyclophosphamide 600 mg/sm, Methotrexate 40 mg/sm, 5‐Fluorouracil 600 mg/sm d1,8 q28 (CMF) for three cycles, in either neo‐adjuvant or adjuvant setting. All HER‐positive patients received targeted therapy with Trastuzumab for 1 year. Disease‐free and overall survival (DFS and OS, respectively) were estimated according to Kaplan‐Meier method. Three hundred and thirty patients were enrolled, where 77.9% of cases were treated in an adjuvant setting; 65.5% received breast conservative surgery, 72.4% axillary dissection. 75.5% of cases presented estrogen receptor positivity, 66.7% progesterone receptor positivity; 18.5% of patients presented HER2‐positive BC, 16.1% triple negative disease. Twenty‐eight (8.5%) developed grade III‐IV hematologic toxicity; nine patients (2.7%) developed grade III neurological toxicity. Loco‐regional DFS was 99.6% at 1 year, 97.1% at 5 years, 95.9% at 7 years. Corresponding distant DFS was 98.4%, 90.2%, and 88.8%. One, 5, and 7‐year OS was 99.6%, 94.9%, and 91.2%, respectively. Chemotherapy with ATx3→CMFx3 is confirmed safe and effective at 6.7 years follow‐up. These results appear comparable to those reported in regulatory trials of most commonly prescribed anthracycline and taxane‐based regimens.