SAGE-Hindawi Access to Research Pathology Research International Volume 2011, Article ID 504940, 7 pages doi:10.4061/2011/504940 Review Article Issues Related to Sentinel Lymph Node Assessment in the Management of Breast Cancer— What Are Relevant in Pathology Reports? Patricia Tai,1 Kurian J. Joseph,2 and Edward Yu3 1 Department of Radiation Oncology, Allan Blair Cancer Center, SK, Canada S4T 7T1 2 Department of Oncology, Cross Cancer Center, AB, Canada T6G 1Z2 3 Radiation Oncology Division, London Regional Cancer Program, ON, Canada N5A 4L6 Correspondence should be addressed to Patricia Tai, ptai2@yahoo.com Received 12 September 2010; Accepted 19 January 2011 Academic Editor: Sunati Sahoo Copyright © 2011 Patricia Tai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Most cancer centers now perform sentinel node (SN) biopsies. The limited number of SNs sampled compared with an axillary dissection has allowed more comprehensive lymph node analysis resulting in increased detection of micrometastases. Many node- negative cases are now reclassiﬁed as micrometastatic. Recent research on SN biopsy focuses on whether axillary dissection is always necessary when the SN is positive. Some subgroups of patients have a higher risk of more nodal metastases when completion axillary dissections were performed. This paper summarizes the diﬀerent studies and examines what are the clinically relevant items to report on SN node pathology: volume or size of nodal metastasis, location within the node, extranodal extension, number of involved SN(s) and non-SN(s), total number of SN, and total number of nodes on axillary dissection, if performed. 1. Introduction Breast cancer is estimated to have an incidence of 22,700 and will cause 5400 cancer deaths among females in Canada in 2009 as per Canadian Cancer Society Statistics [1]. Better prognostic factors to aid oncologists in making treatment decision will beneﬁt a signiﬁcant number of patients. The nodal staging of breast cancer generally involved a level I and II axillary dissection. To reduce the risk of surgical complications, sentinel node (SN) biopsy has been widely used in the last decade. Nodal ratio (absolute number of involved nodes/number of nodes resected) was recently proposed to have a greater prognostic value than absolute number of involved nodes [2–7]. Since the paper by Woodward et al. [8] from the International Nodal Ratio (NR) Working Group, there are a few more studies conﬁrming this [9]. In a recent study, relapse free and overall survival rates were not diﬀerent according to the absolute number of involved nodes (P = .166, P = .248, resp.) [10], but on multivariate analysis, the NR was an independent prognostic factor for relapse free and overall survival (Hazard ratio, HR = 4.246, P < .001; HR = 7.764, P < .001), respectively. Diﬀerent dividing lines for NR have been used in the literature. Our previous work showed a survival beneﬁt for regional nodal radiotherapy (RT) when the NR of axillary nodes is 0.25 or more [11]. In this study, patients were categorized into three NR groups; low (LNR, ≤25%), medium (MNR, >25% to ≤75%) and high (HNR, >75%) nodal involvement. This categorization follows previous literature using British Columbia data [2] and American data [8, 12]. Truong et al. found that 25% is a good dividing line for grouping [2]. With sentinel node (SN) mapping technique, the min- imum number of nodes required for accurate staging becomes less. This is because SN biopsy technique uses radio- isotope and dye to guide the search for ﬁrst drainage node(s) accurately. SN biopsy correctly identiﬁes the involved node which could be missed by axillary node dissection without any guidance [13]. Analysis of frozen section of SNs is an accurate method for metastasis detection, allowing axillary dissection when positive at the same operative setting [14].