Antineoplastic Agents, Hormonal/administration & dosage; Antineoplastic Combined Chemotherapy Protocols/administration & dosage; Breast Neoplasms/drug therapy; Adult; Axilla; Breast Neoplasms/metabolism; Breast Neoplasms/pathology; Breast Neoplasms/surgery; Chemotherapy, Adjuvant; Confounding Factors, Epidemiologic; Cyclophosphamide/administration & dosage; Disease-Free Survival; Drug Administration Schedule; Epirubicin/administration & dosage; Epirubicin/analogs & derivatives; Female; Fluorouracil/administration & dosage; Follow-Up Studies; Glucuronates/administration & dosage; Humans; Italy; Kaplan-Meier Estimate; Lymph Node Excision; Mastectomy, Segmental; Methotrexate/administration & dosage; Middle Aged; Multivariate Analysis; Neoplasm Staging; Neoplasms, Hormone-Dependent/drug therapy; Prognosis; Proportional Hazards Models; Receptors, Estrogen/metabolism; Receptors, Progesterone/metabolism; Risk Factors; Tamoxifen/administration & dosage; Treatment Outcome