Introduction: Optimal lymph node (LN) yield from neck dissection in patients with oral cavity squamous cell carcinoma (OCSCC) is critical from a quality metric and its impact on outcomes. A yield of >18 lymph nodes per neck dissection has been previously shown to provide a survival advantage. However, this absolute metric does not address variations in the type of neck dissection performed or age of patients with OCSCC.
Methods: A retrospective review was performed of all patients with oral cavity squamous cell carcinoma (OCSCC) who underwent neck dissection at Michigan Medicine from 1998 to 2011. The same cohort was obtained using the Surveillance, Epidemiology, and End Results (SEER) database from 2004 - 2011. A total of 255 and 8,281 patients were identified. Total number of lymph nodes yielded from the dissection, number of levels dissected and positive lymph nodes were collected from surgical pathology. Additional clinicopathologic data were collected from the electronic medical record. Survival data was calculated using the Cox regression method.
Results: The identification of < 4 LN/level was associated with worse overall survival (OS) (hazard ratio [HR], 2.37; 95% confidence interval [CI], 1.60 – 3.49; P < 0.001) and disease specific survival (DSS) (hazard ratio [HR], 2.46; 95% confidence interval [CI], 1.51 – 3.99; P < 0.001). < 4 LN/level yielded the maximal HR on univariate analysis. This remained significant after controlling for age, sex, stage, rate of perineural invasion, extracapsular extension and nodal status. As patients age, the total number of nodes examined decreases and the nodal ratio increases in N+ patients. However, the total number of positive nodes does not change.
Conclusion: Lymph node yield has previously been described as a prognostic factor in head and neck cancer patients. Here, we propose the use of lymph node yield per level as a more accurate measure of quality in neck dissection. In our cohort, a lymph node yield of > 4 lymph nodes per level is associated with a statistically significant overall and disease specific survival advantage in OCSCC patients. However, clinicians should apply these findings with caution to the elderly population in which the LN yield overall decreases secondary to atrophy of fibrofatty tissue.