The American College of Surgeons Oncology Group (ACOSOG) Z0011 trial reported that axillary lymph node dissection (ALND) did not change the recurrence and overall survival (OS) rates in patients with lumpectomy and one to two positive nodes detected by sentinel lymph node biopsy (SLNB). The aim of this study was to determine whether patients with mastectomy and pathological N1 disease found by SLNB could forego ALND.