Occult metastases in sentinel nodes of 200 patients with operable breast cancer

Background: Up to 30% of patients with operable breast cancer and negative regional lymph nodes experience disease recurrence within 10 years. Serial sectioning and immunohistochemical staining of these nodes have revealed 9% to 30% occult metastases. Methods: Sentinel nodes from 200 patients with T1 and T2 invasive breast ca rcinoma were step-sectioned at 2- to 3-mm intervals, fixed in 10% formalin, and embedded in paraffin. Sections were taken from the face of the blocks and stained with hematoxylin and eosin (H&E). The blocks were then cut comp letely, and sections at .25-mm. intervals were stained with cytokeratin and examined. Results: Tumor metastases were found in 34 patients when the sentinel nodes were examined at 2- to 3-mm intervals, and in an additional 51 patients wh en the nodes were sectioned in their entirety at .25-mm intervals and stain ed with cytokeratin, bringing the total number of patients with metastases to 85. Of the 51 patients whose metastases were detected by 2- to 3-mm sect ioning and cytokeratin staining, 27 had isolated tumor cells and 24 had clu sters of innumerable malignant cells, all of which were visualized and conf irmed by H&E staining of the adjacent sections. Conclusions: Histologic examination of sentinel nodes of patients with inva sive breast cancer sectioned at 2- to 3-mm intervals and stained with H&E s ignificantly underestimates nodal metastases. Sectioning of the entire sent inel nodes at .25-mm intervals and staining with cytokeratin detects metast ases as either isolated cells or as clusters.