Background: The purpose of this study was to investigate the incidence of micrometastases from squamous cell carcinomas of the upper aerodigestive tract in neck dissection specimens, and to determine whether features of the primary tumor might be of prognostic value for metastasizing.
Methods: Seventy-six originally pNO staged neck dissection specimens from 60 patients were evaluated using serial sectioning in 10-micrometer intervals, H&E staining and immunostaining with an antibody to pan-cytokeratin. The influence of the variables pT-category, cytologic grade, and maximum depth of invasion of the primary tumor on the nodal status was analyzed in 128 patients.
Results: The examination of 1020 lymph nodes from 76 neck dissection specimens revealed 8 micrometastases in 6 specimens (7.9%) from 6 patients with oral and pharyngeal primaries, resulting in upstaging. Six micrometastases were located in lymph nodes of 3-6 mm in diameter. Depth of invasion was the only significant risk factor for metastasizing selected in logistic regression.
Conclusion: The surgeon should be aware of a relatively high incidence of micrometastases from oral and pharyngeal carcinomas, which are neither detectable preoperatively nor histopathologically by a reasonable effort. The measurement of the maximum depth of invasion of the primary can delineate a group of patients who should be treated by elective neck dissection.