Adjuvant Radiotherapy Significantly Increases Neck Control and Survival in Early Oral Cancer Patients with Solitary Nodal Involvement: A National Cancer Registry Database Analysis

We assessed the role of adjuvant radiotherapy on neck control and survival in patients with early oral cancer with solitary nodal involvement. We identified pT1-2N1 oral cancer patients with or without adjuvant radiotherapy from the 2007-2015 Taiwan Cancer Registry database. The effect of adjuvant radiotherapy on 5-year neck control, overall survival (OS) and disease-free survival (DFS) were calculated using the Kaplan-Meier method, log-rank tests, and Cox regression analysis. Of 701 patients identified, 505 (72.0%) received adjuvant radiotherapy and 196 (28.0%) had surgery alone. Patients receiving adjuvant radiotherapy were more likely to be aged <65 years, pT2 stage, poorly graded and without comorbid conditions (all, p < 0.05). The 5-year OS and DFS differed significantly by receipt of adjuvant radiotherapy. Multivariable analysis showed adjuvant radiotherapy significantly associated with better 5-year OS (adjusted hazard ratio (aHR), 0.72; 95% confidence interval (CI), 0.54-0.97; p = 0.0288) and DFS (aHR, 0.64; 95% CI, 0.48-0.84; p = 0.0016). Stratified analysis indicated the greatest survival advantage for both 5-year OS and DFS in those with pT2 classification (p = 0.0097; 0.0009), and non-tongue disease (p = 0.0195; 0.0158). Moreover, adjuvant radiotherapy significantly protected against neck recurrence (aHR, 0.30; 95% CI, 0.18-0.51; p < 0.0001). Thus, adjuvant radiotherapy is associated with improved neck control and survival in these early oral cancer patients.