Immunocytologic detection of isolated tumor cells in bone marrow of patients with squamous cell carcinomas of the head and neck region.

The well-documented specificity of anticytokeratin monoclonal antibodies for detection of epithelial micrometastatic cancer cells in bone marrow as a prognostic indicator inspired us to apply this approach to patients with squamous cell carcinomas (SSC) of the head and neck region. The sensitivity of the broad-spectrum anticytokeratin monoclonal antibody (mAb) A45-B/B3 used for tumor cell detection was demonstrated by immunostaining of cryostat sections from the respective primary tumors. Analysis of 31 patients with SSC revealed A45-B/B3-positive cells in 10 cases (32.3%) at frequencies of 1-207 per 1 x 10(6) mononuclear cells. Most specimens displayed isolated tumor cells, while cell clusters were found in only two cases (6.5%). The present data suggest that hematogenous dissemination of cancer cells is more frequent than expected from clinicopathologic staging of patients with SSC of the head and neck region.