Re-examining predictors of pathologic lymph node positivity in clinically node negative oral cavity cancer

Elective lymph node dissection (ELND) is performed for many early-stage oral cavity squamous cell carcinomas (OCSCC) with clinically negative necks (cN0), often guided by depth of invasion (DOI). However, DOI is less validated in non-tongue OC sites, and often correlates with other adverse features. We sought to evaluate the utility of DOI versus other factors for independently predicting pathologic lymph node positivity (pN+) in patients with cN0 OCSCC.

Patients with cN0 OCSCC diagnosed from 2010 to 2015 undergoing primary surgery were identified in the National Cancer Data Base.

5060 cN0 OCSCC patients met inclusion criteria. The presence of lymphovascular invasion (LVI) was the strongest independent predictor of pN+ (odds ratio [OR] = 4.27, 95% confidence interval [CI] 3.36-5.42, P < 0.001). High histologic grade also strongly predicted pN+ (OR 3.33, 95% CI 2.20-4.60, P < 0.001). DOI had no association with the likelihood of pN+ among all OCSCC patients, but was predictive among patients within the oral tongue subset (OR 2.01, 95% CI 1.08-3.73, P = 0.03 for DOI > 20 mm vs. DOI: 2.0-3.99 mm).

LVI and grade are the strongest independent predictors of pN+ in cN0 OCSCC. Contrary to prior studies, DOI was not found to be a predictor of pN+ among patients with cN0 OCSCC. However, DOI was a predictor of pN+ or the oral tongue subset, albeit still less strongly than LVI or grade. These findings could potentially be used to better identify a subset of cN0 OCSCC patients who could be considered for omission of ELND in future studies.