Impact of Postoperative Neck Radiotherapy Volumes on Long-Term Unstimulated Saliva Flow Following Primary Surgery and Ipsilateral Neck Dissection for Oral Cavity Squamous Cell Carcinoma

Abstract

Background: We investigate the association of postoperative radiotherapy (PORT) volumes and salivary function in oral cavity SCC (OSCC). Methods: OSCC patients undergoing PORT 2005–2021 underwent modified Schirmer test (MST) pre-PORT, 6 and/or 12 months post-PORT. Hyposalivation rates were compared by PORT volumes. MVA identified predictors for chronic hyposalivation. Results: Among 165 eligible patients, 88 (53%) received bilateral, 66 (40%) ipsilateral, and 11 (7%) no-neck (primary-only) PORT. Baseline characteristics were similar, except more N2b/N2c disease received bilateral PORT vs. ipsilateral or no-neck (60% vs. 36% vs. 0%, p < 0.001). Baseline hyposalivation was similar (26% vs. 30% vs. 18%, p = 0.67). Hyposalivation occurred more frequently in bilateral vs. ipsilateral vs. no-neck PORT at 6 (90% vs. 62% vs. 9%) and 12 months (90% vs. 48% vs. 0%) (both p < 0.001). On MVA, bilateral neck PORT and smoking predicted chronic hyposalivation. Conclusion: Increasing PORT volumes predict saliva function recovery and chronic hyposalivation, informing treatment discussions.