Microstaging of sentinel lymph nodes.

My colleagues at the H. Lee Moffitt Cancer Center in Tampa have advanced significantly the understanding of cytokeratin immunohistochemical staining (CK IHC) for sentinel lymph node processing. In this important paper, presented at the Annual Meeting of the Society of Surgical Oncology and published in this issue of Annals of Surgical Oncology, Schreiber and colleagues1 confirmed, with comparison of tumor size versus positive nodal status, that CK IHC staining of sentinel lymph nodes led to a significant upstaging in patients with tumor sizes under 2 cm (T1a, T1b, T1c lesions). Moreover, the authors note that CK IHC staining of sentinel nodes shifted 9.4% of patients from a diagnosis of stage I to stage II. This previously undetected presence of tumor (a microstaging shift, or upstaging) may account for a significant proportion of stage I breast cancer failures, not found previously by hematoxylin and eosin (HE 63.8% of patients had HE 56.4% of nodes) were upstaged by CK IHC. As confirmed in this analysis, patients with more advanced T2 and T3 lesions were less frequently upstaged using sentinel node CK IHC: 5.9% of nodepositive patients and 20.6% of nodes for T2 and T3 lesions. In an analysis performed at Brown University using the Rhode Island State Tumor Registry, computerized data from nine hospitals of the Hospital Association of Rhode Island confirmed positive nodes in T1a and T1b lesions (9.8% and 19.4%, respectively).2 This overall frequency of 18% node positivity found in T1a1T1b lesions is in a median position compared to other reports, with the great variation perhaps due to the smaller sampling sizes of the other reports.3 In a more recent analysis of both Rhode Island and Massachusetts tumor registries, records of 12,030 patients with T0 and T1 lesions were examined.4 Of these, 2185 had invasive tumors ¶1.0 cm in diameter (T1a and T1b), which represented 18% of all breast cancers in this study. Although the diagnoses were made by many different pathologists, results from these 2185 patients showed a node positivity of 17%. The current series from the University of South Florida reported overall frequencies of 11.1% upstaging for T1a lesions and 15.7% for T1b lesions, which is very similar to frequencies in the combined Rhode Island and Massachusetts database. An additional effect, therefore, appears evident in the study for predicting enlargement of the frequency of nodal positivity in the small lesions which, for many patients, have fewer potential nodes to evaluate pathologically. Contemporary pathology evaluations in most academic centers include bivalving nodal tissue after dissection, with evaluation of only one or two surfaces, typically, from the node tissue in question. The authors have emphasized that the CK positivity adds even greater importance in early lesions to ensure accurate sensitivity (true positives) in Tis, T1a, and T1b lesions. The upstage frequency of CK-positive, HE T1a, 5.9%; and T1b, 6.5%. One cannot, however, dismiss the fact that there was also upstaging of CK positivity in latter stage lesions: 15.8% in T1c and 10% in T2. Thus, the overall upstaging frequency in this database of 210 patients was 9.4%, a number that is not inconsequential and should be regarded as highly important to evaluate objective planning and application of adjuvant chemotherapy in these patients. Moreover, the addition of adequate objective Received August 21, 1998; accepted August 28, 1998. From the Department of Surgery, Brown University School of Medicine, Rhode Island Hospital, Providence, Rhode Island. Address correspondence to: Kirby I. Bland, MD, Dept. of Surgery, Brown University School of Medicine, Rhode Island Hospital, 593 Eddy St., Providence, RI 02903. Annals of Surgical Oncology, 6(1):15–16 Published by Lippincott Williams & Wilkins © 1999 The Society of Surgical Oncology, Inc.