Clinicopathologic Features Associated With Having Four or More Metastatic Axillary Nodes in Breast Cancer Patients With a Positive Sentinel Lymph Node Aeisha K. Rivers, MD, 1,2 Kent A. Griffith, MS, MPH, 2 Kelly K. Hunt, MD, 3 Amy C. Degnim, MD, 4 Michael S. Sabel, MD, 5 Kathleen M. Diehl, MD, 5 Vincent M. Cimmino, MD, 5 Alfred E. Chang, MD, 5 Peter C. Lucas, MD, 6 and Lisa A. Newman, MD, MPH, FACS 5 1 Department of Surgery, St. JosephÕs Hospital and Medical Center, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 2 Department of Biostatistics, University of Michigan Comprehensive Cancer Center, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 3 Department of Surgery, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 4 Department of Surgery, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905 5 Department of Surgery, University of Michigan Comprehensive Cancer Center 1500 E. Medical Center Drive, 3308 Cancer Center, Ann Arbor, Michigan 48109-0932 6 Department of Pathology, University of Michigan Comprehensive Cancer Center, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, Michigan 48109 Background: The survival benefit of a completion axillary lymph node dissection (ALND) in patients after removal of a metastatic sentinel lymph node (SLN) is uncertain and is under study in ongoing clinical trials. The completion ALND remains necessary, however, for the identification of cases with at least four metastatic lymph nodes, in which extended-field locoregional and/or postmastectomy radiation will be recommended. Our goal was evaluate clinicopathologic features that might serve as surrogates for determining which patients with a positive SLN are likely or unlikely to belong to this high-risk subset. Methods: Records were reviewed for 285 patients from 2 comprehensive cancer centers who underwent completion ALND after resection of a metastatic SLN from 1995 to 2002. Clini- copathologic features were analyzed by univariate and multivariate logistic regression. Forty- one cases (14%) were found to have at least four positive nodes after ALND. Results: FisherÕs exact test revealed the following features to be significantly (P < .05) associated with having four or more nodal metastases: tumor size >2 cm, lymphovascular invasion, an increasing ratio of positive SLNs to the total number of resected SLNs, ex- tranodal extension, and the size of the SLN metastasis. Patients whose largest SLN metastasis was <2 mm had only a 1.4% risk of having four or more metastatic nodes (P < .0001). Conclusions: We conclude that patients with SLN micrometastases face an extremely low likelihood of having extensive nodal disease on completion ALND. Patients with larger pri- mary tumors, lymphovascular invasion, and extranodal extension are more likely to have ALND findings that will affect their cancer management. Key Words: Breast cancer—Sentinel lymph node metastases—Axillary lymph node dissec- tion—Prediction of risk. The standard level I/II axillary lymph node dis- section (ALND) has been a routine component of surgical care for breast cancer patients over the past century: it provides the prognostically powerful Received March 15, 2005; accepted August 1, 2005; published online January 1, 2006. Address correspondence and reprint requests to: Lisa A. Newman, MD, MPH, FACS; E-mail: lanewman@umich.edu. Published by Springer Science+Business Media, Inc. Ó 2006 The Society of Surgical Oncology, Inc. Annals of Surgical Oncology, 13(1): 36)44 DOI: 10.1245/ASO.2006.03.080 36