Adoption of adjuvant chemotherapy in high-risk salivary gland malignancies

Background The present study characterizes national trends in the utilization of adjuvant chemotherapy to treat salivary gland malignancies. Methods The National Cancer Database was queried for salivary gland malignancies treated by surgery with radiation in 2004-2019. Proportions of patients receiving adjuvant chemotherapy over the study period were analyzed by linear regression. The impact of chemotherapy on overall survival was assessed using Kaplan-Meier and Cox proportional hazards analyses. Results Among 15 965 patients meeting inclusion criteria, 2355 (14.8%) received adjuvant chemotherapy. Chemotherapy utilization significantly increased from 4.9% to 16.5% over the study period (p < 0.001). No survival benefit was observed with adjuvant chemotherapy on propensity score-matched Kaplan-Meier analysis (HR: 0.98; 95% CI: 0.86-1.11; p = 0.72) or multivariable Cox regression (HR: 0.92; 95% CI: 0.78-1.09; p = 0.34). Conclusions Adjuvant chemotherapy has been increasingly utilized to treat salivary gland malignancies in recent years. Our findings highlight the importance of obtaining high-quality prospective data regarding the benefit of chemotherapy.