[Occult metastasis in sentinel lymph node in early-stage breast cancer].

Purpose: sentinel lymph node biopsy in early-stage breast cancer patients has been substituting the total axillary lymph node is presented dissection. The technique of processing the sentinel lymph node and the aim of this study was to investigate the efficacy of occult metastasis identification based on the standard histological and immunohistochemical examination.

Methods: between 2002 and 2005, 266 sentinel lymph nodes were harvested from axillary biopsy of 170 patients with early stage breast cancer. All lymph nodes were considered to be negative according to standard intra-operative cytological assessment. Lymph nodes were transversally sectioned in four or five slices and embedded in paraffin blocks. Two paraffin-embedded tissue sections with 4 microm in thickness were mounted on glass slides and stained with hematoxylin-eosin and immunoperoxidase (cytokeratin AE1/AE3) techniques.

Results: standard histological examination identified metastasis in 22 patients (12.9%) and micrometastatic disease was observed in six of these patients (3.5%). The immunohistochemical examination identified metastatic disease in 16 patients (9.4%). Among them, isolated tumor cells were observed in 11 (6.5%) and micrometastases were identified in five (2.9%).

Conclusions: the association of the standard histological examination and immunohistochemical technique increases the chances of sentinel lymph node metastasis identification.