Dissection of the submuscular recess (sublevel IIb) in squamous cell cancer of the upper aerodigestive tract: prospective study and systematic review of the literature.

Background: Selective neck dissection is commonly used to clear occult neck metastases in the N0 neck. The aim of this study was to identify the incidence of occult metastases in lymph nodes of sublevel IIb (submuscular recess; SMR) in upper aerodigestive tract squamous cell carcinoma in the setting of clinically and radiologically staged N0 necks and to perform a systematic review of the literature on the incidence of metastases in this setting.

Methods: We conducted a prospective study of 50 neck dissections and systematic review of the literature.

Results: (A) Prospective study: Tissue dissected out from the SMR was sent separately for histopathologic analysis. Between 0 and 7 nodes were harvested from sublevel IIb. One patient had a metastatic node in sublevel IIb with extracapsular spread in the ipsilateral neck. No other positive nodes were detected. Sixteen necks showed occult metastases at other levels. (B) Systematic review: The review identified 14 articles with 903 necks suitable for inclusion. The overall incidence of metastatic disease at this sublevel in the context of an N0 neck from any site is 2.0% (18 of 903). The incidence of occult metastatic disease in sublevel IIb for oral cavity, oropharyngeal, and laryngeal cancer is 3.9% (11 of 279), 5.2% (5 of 96), and 0.4% (1 of 230) patients, respectively. Contralateral positive nodes (0.9%) and isolated metastases (0.3%) at this sublevel were rare.

Conclusion: Nodal metastases are uncommon in the SMR even in the presence of positive nodes in adjacent sublevel IIa. There appears to be no advantage in performing contralateral SMR dissection in N0 necks and in laryngeal primaries.