Practical Tips in the Management of the N0 Neck: Sentinel Lymph Node Biopsy

The surgical management of the N0 neck in patients with oral squamous cell carcinoma (OSCC) has been long debated and evolved dramatically over the last century. Since the introduction of radical neck dissection by Dr. Crile in 1906, there has been a slow but steady trend to de-escalate surgical therapy to reduce morbidity without compromising oncologic safety. Cervical lymphadenectomy/elective neck dissection remains the gold standard in comprehensive pathologic interrogation and surgical staging of the regional lymph nodes in patients with oral cavity cancer. This, however, does come at a cost. Risks include injury to neurovascular structures, shoulder dysfunction, surgical scarring, and bleeding. In patients with early-stage, thin, oral cavity squamous cell carcinoma, elective neck dissection may be overtreatment in surgical staging and oncologic therapy. In this cohort of patients, sentinel lymph node biopsy (SLNB) may be an appropriate alternative to surgical staging. Sentinel lymph node biopsy is a minimally invasive technique for staging OSCC and can potentially reduce the morbidity associated with selective neck dissection. The first published report of lymphatic mapping for cancer patients was completed by Seaman and Powers in 1955, in which they described the injection of breast tumors with radiolabeled colloidal gold and mapped the progression of the tracers through the regional lymphatics. Five years later, Gould et al. coined the term “sentinel node” when describing a level II cervical lymph node consistently identified during parotidectomy for malignant tumors – the status of which guided the operators to complete or forgo neck dissection. The concepts of a “sentinel lymph node” and lymphatic mapping were first used to reliably and accurately predict regional cancer spread by Morton et al. in 1992. This group reported data from 223 patients with stage I cutaneous melanoma in which they performed a vital blue dye-directed sentinel node identification and regional lymphadenectomy. Since then, there have been many retrospective and prospective studies, and more recently, two randomized controlled clinical trials comparing SLNB to elective selective neck dissection in early-stage OSCC. In summary, the data suggest a negative predictive value of a negative sentinel node biopsy between 95 and 100%. Moreover, in a subset of early-stage oral cavity cancers, sentinel lymph node biopsy demonstrates oncologic equivalence at 2 and 5 years postoperatively compared to elective neck dissection with substantially reduced morbidity and hospital stay. This chapter aims to discuss the practical pearls and pitfalls of sentinel lymph node biopsy for the N0 neck in managing squamous cell carcinoma.