Current state of neck dissection in the United States

Abstract

The status of the cervical lymph nodes is the most important prognosticator in head and neck squamous cell carcinoma. The neck dissection is both a therapeutic and staging procedure and has evolved to include various types with standardized level designations (I-VI) for lymph node groups: the radical neck dissection, modified radical neck dissection, the selective neck dissection, and the extended neck dissection. The gross and histologic examination of a neck dissection should provide the critical information (size of metastasis, number of lymph nodes involved) for staging purposes. Additionally, extracapsular spread of lymph node metastasis must be reported because of its significance as an adverse prognosticator. Current dilemmas in nodal disease are the detection of micrometastases, isolated tumor cells, and molecular positivity. The significance of these categories of disease is still unclear, though they may explain a subset of the estimated 10% of the regional recurrences in the neck despite pathologic node negativity by traditional methods of evaluation. Sentinel lymph node biopsy has been recently applied to head and neck squamous cell carcinoma to enhance the management of the clinicoradiographically node negative patients. While still investigational, sentinel lymph node biopsy shows promise in selecting patients who require a neck dissection. Rapid highly automated real-time RT-PCR based platforms will allow for incorporation of molecular findings into the intraoperative evaluation of a sentinel lymph node.

Fig. 1

Level designations of lymph node groups in the neck

Fig. 2

Gross image of a cross section of matted nodes involving extranodal structures including the internal jugular vein (arrow). At many institutions the inked margin of neck dissection is relevant to help plan/map three dimensional conformal radiotherapy

Fig. 3

a OCT embedded cut surface of a micrometastasis in 3 mm lymph node. SCC notoriously illicits a desmoplastic stromal reaction that allows for gross detection in many cases, especially if a lymph node is sliced thinly at ~1 mm as shown here. b H&E demonstrating a micrometastasis (40×). c ITC in a lymph node detected by a cytokeratin immunostain (100×). d On close examination in that area, these cells are evident on the corresponding H&E as well (400×)

Fig. 4

Schematic representation of a future triaging algorithm for sentinel lymph node evaluation. Such a protocol would involve fixing alternate slices and evaluating for micrometastasis on permanent section using a traditional sentinel lymph node protocol consisting of levels and immunostains for cytokeratin. The other slices should be embedded in OCT for molecular analysis. H&E frozen section stains as morphologic quality assurance should be performed followed by submission of sections directly into a nucleic acid fixative to be placed on an rapid automated platform such as the GeneXpert^© system depicted here for real-time RT-PCR analysis. In the ideal state, the frozen section and molecular component of this procedure should take ~40 min, which, if positive, allows the surgeon to perform the neck dissection in one procedure rather than reoperating pending the permanent results