Structure of interleukin 16 resembles a PDZ domain with an occluded peptide binding site

BACKGROUND: Cervical lymphadenectomy to remove metastatic disease in level II encompasses lymph nodes associated with the upper third of the internal jugular vein and the adjacent spinal accessory nerve (SAN). Conservative neck dissection (ND) preserves these structures but requires manipulation of the SAN to remove tissue located in the posterosuperior aspect of level II. Limiting the dissection to the nodal group anterior to the SAN may reduce operating time and limit injury to it without compromising the removal of lymph nodes at risk for involvement with cancer. METHODS: Seventy-one patients with squamous cell carcinoma of the head and neck treated with cervical lymphadenectomy at two separate institutions were prospectively evaluated. One hundred two neck dissection specimens were histologically analyzed for number of lymph nodes present and number involved with cancer. At the time of surgery, level II was separated into the supraspinal accessory nerve component (IIa) and the component anterior to the SAN (IIb). Nodal involvement in level II was analyzed according to characteristics of the cancer at the primary site as well as nodal involvement of other levels. RESULTS: Neck dissections were most commonly done for cancer of the oral cavity (n = 33), followed in frequency by the larynx (n = 17), oropharynx (n = 7), skin of face (n = 4), unknown primary (n = 4), and other sites (n = 6). Eighty NDs were selective and 22 were either radical or modified radical NDs. Pathologic staging of the neck specimen was most commonly N0 (n = 61), followed in frequency by N1 (n= 17), N2 (n= 11), and N3 (n= 11). Data were unclear for two specimens. Level IIb contained an average of 6.9 nodes and the IIa component contained an average of 4.2 nodes. Level II contained metastatic disease in 31 of 39 node positive specimens (79%). Level IIa was involved with cancer in four cases, all of which were preoperatively staged N2 or greater. CONCLUSIONS: The additional time required and morbidity associated with dissection of the supraspinal accessory nerve component of level II may not be necessary when performing elective ND. More research with larger numbers of patients, long-term follow-up, and meticulous tissue analysis is needed to permit conclusions as to where to draw the line in determining extent of cervical lymphadenectomy.