1103 Background: The American College of Surgeons Oncology Group (ACOSOG) Z0011 trial demonstrated that, for patients with clinical T1-T2, N0 breast cancer and one or two positive sentinel lymph nodes undergoing breast conserving therapy, there was no difference in local-regional recurrence (LRR), disease-free survival or overall survival (OS) between patients who underwent sentinel lymph node dissection (SLND) alone or completion axillary lymph node dissection (ALND). However, there were a limited number of invasive lobular carcinoma (ILC) participants (7%) in the study. In addition, it is known that ILC has a different pattern of metastases, frequently presenting as small foci requiring immunohistochemistry for detection. Together, these considerations raise concern regarding the applicability of the ACOSOG Z0011 data to patients with ILC. Methods: Patients with ILC who met the ACOSOG Z0011 eligibility criteria were identified from the Surveillance, Epidemiology, and End Results database (1998-2009). Patients were evaluated based on the extent of axillary surgery: SLND alone or ALND. Clinicaloutcomes of the two groups were compared. Results: At a median follow-up of 71 months, there were no LRRs in the SLND arm, and only 4 (0.45%) in the ALND arm. There were no differences in OS or disease-specific survival between the two groups. Conclusions: Omission of completion ALND is appropriate in patients with ILC who fulfill the ACOSOG Z0011 eligibility criteria.