Implications of Tumor Size, Subsite, and Adjuvant Therapy on Outcomes in pT4aN0 Oral Cavity Carcinoma

Objective: To determine if tumor size, subsite, and adjuvant radiation therapy (AXRT) are associated with overall survival (OS) in patients with pT4aN0 oral cavity squamous cell carcinoma (OSCC) who underwent mandibulectomy with negative surgical margins (NSMs). Study Design: Retrospective cohort study. Setting: National Cancer Database (NCDB). Subjects and Methods: Retrospective analysis of the NCDB that included patients diagnosed with pT4aN0 OSCC who underwent mandibulectomy with NSMs between 2004 and 2015. The association of age, Charlson-Deyo score (CDS), tumor size, subsite, and AXRT with OS was analyzed. The cases were divided into 3 subgroups based on maximal tumor dimension for subgroup analysis; tumors ≤2.0 cm, tumors 2.1 to 4.0 cm, and tumors >4.0 cm. Results: For the entire cohort; age (P <.001; hazard ratio [HR], 1.03; 95% confidence interval [CI], 1.02-1.03), CDS (P =.013; HR, 0.57; 95% CI, 0.37-0.89), tongue subsite (P =.003; HR, 2.01; 95% CI, 1.27-3.40), floor of mouth subsite (P =.001; HR, 1.76; 95% CI, 1.28-2.42), tumor size (P <.001; HR, 0.57; 95% CI, 0.45-0.72), and AXRT (P <.001; HR, 1.46; 95% CI, 1.24-1.72) were associated with OS on multivariate analysis. On subgroup analysis, AXRT not significantly associated with OS in patients with gingival, hard palate, retromolar trigone, and not specified tumors ≤2.0 cm (P =.323; HR, 1.29; 95% CI, 0.78-2.15). Conclusions: In patients with pT4aN0 OSCC who underwent mandibulectomy with NSMs, age, CDS, tongue subsite, floor of mouth subsite, tumor size, and AXRT are associated with OS. AXRT was not significantly associated with overall survival in patients with gingival, hard palate, retromolar trigone, and not specified tumors ≤2.0 cm.