Evaluation of Sentinel Lymph Node Drainage Patterns in Early-Stage Oral Cavity Cancer

Abstract

Surgery is the mainstay for squamous cell carcinoma of the oral cavity (OSCC), which includes an elective neck dissection. To limit morbidity of neck dissection, sentinel lymph biopsy (SLNB) has been introduced to identify patients at risk for nodal metastasis. While the data has thoroughly examined the relationship between SLNB in patients with unilateral lymph node drainage, little information exists on the rate of bilateral lymph node drainage patterns in lateralized OSCC. This study sought to examine the incidence of bilateral lymph node drainage patterns using sentinel node mapping in early stage OSCC. This retrospective review of the electronic medical records at Rush University Medical Center focused on patients who underwent a SLNB based on CPT codes 38724, 38900, 38542, and 38510. From this cohort, we limited our analysis to patients with primary clinical T1 or T2 OSCC. Primary outcome was the rate of bilateral nodal drainage on sentinel node mapping based on the SPECT-CT. A total of 54 patients were diagnosed with clinical T1/T2N0 OSCC and underwent a SLNB with SPECT-CT. (1) From the cohort of 54, 15 patients (27.78%) had bilateral sentinel lymph node drainage on SPECT-CT, while 39 patients (72.22%) had unilateral sentinel lymph node drainage. (2) Eleven patients (73.3%) from the bilateral drainage cohort completed appropriate SLN mapping with bilateral nodal assessments. (3) Four patients who had SPECT-CT evidence of bilateral drainage completed unilateral nodal assessment alone. (4) Of the patients with bilateral nodal assessment, 1 (9.1%) patient had a positive sentinel node on the ipsilateral side, 2 (18.2%) were found to have a positive sentinel node in the contralateral neck. (5) Overall, 3 patients (20%) had local-regional recurrence in the bilateral sentinel lymph drainage cohort. Management of early-stage OSCC has evolved to include SLN mapping and biopsy. Our results found that contralateral drainage occurs in 18% of our patients with 2 patients having positive sentinel node in the contralateral neck. Therefore, the rate of contralateral drainage is not clinically insignificant and this result furthers the importance of lymphatic mapping in the early-stage OSCC treatment algorithm.