New technique to assess the axilla for breast cancer metastases using cell separation technology

Accurate staging of the axilla for metastatic disease is critical in deciding on the optimal management of patients with breast cancer. Lymph node status is the most powerful prognostic factor. Current standard surgical management of breast cancer involves axillary dissection for staging. Pathological staging by routine histology, however, is known to understage the disease extent because only one or two sections are taken from each node, a sampling of less than 1% of most nodes. Sentinel node biopsy is currently under trial to determine if thorough pathological staging of the most likely involved node is more accurate than standard pathological assessment of all nodes. The present pilot study was undertaken to investigate an alternative method of assessing all axillary nodes for cancer cells.

After routine material was taken from lymph nodes for standard pathological assessment, discarded parts of nodes were used for the study technique. These node parts were mechanically disaggregated, and the cell suspension centrifuged on a density gradient to separate any tumour cells (into the pellet) from lymphocytes (at the top of the gradient). The pellet was then assessed by haematoxylin and eosin and immunohistochemistry.

The results of the present study proved highly significant. The technique detected metastatic cells in three nodes which were negative on routine pathology, in one case changing the status of the patient from node-negative to node-positive.

It is concluded that the technique examined in the present paper has the potential to reduce sampling error, may offer far more accurate axillary staging than routine histopathology, and should be further evaluated in a controlled trial.