Factors impacting use of adjuvant therapy in lip and oral cavity squamous cell carcinoma: A NCDB analysis.

e18556 Background: Two trials followed by a combined analysis of the trials in head and neck squamous cell carcinoma (SCC) established that the benefit of adjuvant chemotherapy concurrent with radiation (CRT) was only noted in patients with extracapsular extension of nodal disease (ECE) and positive resection margins (PM). Despite this recommendation, other high-risk pathological features including pT3 or pT4 disease, positive lymph nodes, perineural involvement, vascular tumor embolism and level IV or V lymph node involvement have been noted to increase the risk of recurrence and adjuvant chemotherapy has been utilized for these patients. We report an observational study to evaluate the factors impacting use of CRT in patients with oral cavity and lip SCC. Methods: We conducted a retrospective study of patients with oral cavity and lip SCC who underwent resection of primary tumor with or without neck dissection in the reporting hospital in the NCDB database. We compared demographic, clinical and pathological characteristics of patients who received adjuvant CRT versus radiation alone. Multivariate analysis was performed using logistic regression model. Results: Out of the 58,481 patients reported to have surgery in NCDB from 2004 to 2016, 11,413 patients received adjuvant therapy. In univariate analysis, patients who received CRT were most likely less than 65 years of age, males, patients with no insurance or private insurance, lower Charlson Deyo score, Stage IVA, pT4, grade 2 or higher, tumor size > 4cm, positive lymph nodes, involvement of level IV and V nodes, lymphovascular invasion, ECE and PM. In multivariate analysis, factors which influenced receiving CRT were age between 40 and 65 years, males, Stage IVA (compared to Stage I to III), positive nodes, ECE and PM. A total of 984 patients received CRT without having ECE or PM. Conclusions: In addition to ECE and PM, positive lymph nodes was the major pathological factor in patients receiving CRT compared to RT alone.