Adjuvant radiotherapy in the management of major salivary gland tumors: retrospective analysis

Background: This study evaluates long-term survival outcomes of patients submitted to surgery (with or without neck dissection) and adjuvant radiotherapy for major salivary gland tumors, as well as prognostic factors affecting clinical outcomes. Methods: Retrospective analysis was performed on patients treated for major salivary gland tumors between 2006 and 2018. Kaplan-Meier curves for disease-free survival (DFS) and overall survival (OS) were calculated, Cox regression was used for uni- and multivariate analysis to assess prognostic factors. Log-rank tests were used to compare survival outcomes according to neck dissection status, stratified by stage and by histopathological risk. Results: 38 of 77 pts were eligible for analysis. Median follow-up was 63.1 months and median dose delivered was 66 Gy. The 2- and 5-years DFS rates were 79.2% and 72%, and the 2- and 5-years OS rates were 81.5% and 66.6%, respectively. Lymphovascular invasion and neck dissection were identified as possible prognostic factors for DFS and lymphovascular invasion, positive nodes, high histopathological risk and positive margins, for OS. There were no differences observed in DFS and OS curves for high histopathological risk patients according to neck dissection. A difference was found comparing DFS on stage III-IV patients (p=0.02), OS was not different. Conclusions: DFS and OS improvements were not observed in high-risk histology and III-IV stage disease due to study limitations, regardless of neck dissection status. Some of the results shown, although with no statistically significant differences, could reveal the potential of adjuvant radiotherapy in pts unable to perform neck dissection.