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.