Occult metastases in the sentinel lymph nodes of patients with early stagebreast carcinoma - A preliminary study

BACKGROUND. Thirty percent of lymph node negative patients with operable br east carcinoma experience disease recurrence within 10 years. Retrospective serial sectioning of axillary lymph nodes has revealed undetected metastas es in 9-30% of these patients. These occult metastases have been shown to h ave an adverse effect on survival. Serial sectioning (SS) is impractical fo r all axillary lymph nodes harvested from Levels I and II, but it is feasib le if applied only to sentinel lymph nodes. METHODS. Sentinel lymph nodes from 52 patients with invasive breast carcino ma were cut at 2 mm intervals, fixed in 10% formalin, and embedded in paraf fin, Sections were taken from the blocks, stained with hematoxylin and eosi n (H & E), and compared with cytokeratin-stained sections taken at 0.25 mm intervals throughout the entire blocks. RESULTS. Tumor metastases were found in 6 patients (12%) when the sentinel lymph nodes were sectioned at 2 mm intervals and stained with H & E, compar ed with 30 patients (58%) when the same lymph nodes were serially sectioned at 0.25 mm intervals and stained with cytokeratin. Of 24 patients whose me tastases were detected by SS and cytokeratin staining, 12 had isolated tumo r cells and 12 had colonies of several thousand malignant cells. CONCLUSIONS. Routine histologic examination of axillary lymph nodes, includ ing sentinel lymph nodes, in cases of breast carcinoma significantly undere stimates lymph node metastases. This deficiency may be overcome by SS of th e entire lymph nodes and staining with a specific monoclonal antibody. The percentage of patients found to have colonies of cells that were missed by routine sectioning corresponds closely to the percentage of "lymph node neg ative" patients who would be expected to relapse. The true clinical signifi cance of these occult metastases will be determined by long term follow-up. (C) 1999 American Cancer Society.