Predictors of occult lymph node metastases in lip cancer

Objective: The incidence of lymph node metastases (LNM) in squamous cell carcinoma of the lip is modest (8%), making it challenging to identify patients that may benefit from elective pathologic staging evaluation of the neck. We evaluated predictors of LNM in patients with lip cancer in order to potentially refine selection of patients for pathologic staging evaluation of the neck. Study design: Retrospective cohort study. Subjects: Clinically N0 patients with squamous cell carcinoma of the lip that underwent definitive surgical resection and pathologic evaluation of lymph node metastases in the National Cancer Data Base from 2006 to 2013. Methods: Multivariable binomial logistic-regression was used to assess the relationship between occult pathologic lymph node metastasis and potential preoperative predictors including; patient demographics, T-stage, location, and pathologic details. Results: Among 786 patients the overall rate of LNM was 12.1%. Patients were more likely to have LNM with T2 (odds ratio (OR) 2.05; (95% confidence interval (CI) 1.19-3.54) or T3-4 (OR 2.36; CI 1.32-4.22) moderately differentiated (OR 2.65; CI 1.30-5.38) or poorly differentiated (OR 4.37; CI 1.97-9.71), or involvement of the mucosal surface (OR 1.82; CI 1.09-3.03). We created a prediction model based on proportional odd ratios from multivariant binomial logistic-regression analysis from statistically significant factors; incorporating T2-4, moderate/poorly differentiated, or mucosal site. Conclusion: Our prediction model found that patients with two or more risk factors were the best candidates for elective pathologic nodal evaluation.