Radiotherapy for parotid malignancies: patterns of care and impact on overall survival

Abstract

Introduction

Parotid tumors are rare, and no clinical trial data exists to guide postoperative radiation therapy (PORT) usage. We sought to determine the impact of PORT on the overall survival (OS) of patients with parotid malignancies.

Methods

Patient data was queried from the National Cancer Database. Patients with surgical resection of parotid gland carcinomas from 2004 to 2012 were analyzed. Kaplan-Meier and Cox proportional hazards were used to assess OS among those receiving PORT or not. Additionally, variables affecting OS and use of PORT were evaluated.

Results

A total of 12,439 patients were identified for analysis. Increasing T stage, N stage, tumor grade, and positive margin status were predictive of PORT. Survival for patients receiving PORT versus surgery only at 5 and 10 years was 65.5% and 50.3% versus 74.4% and 61.2% for surgery only (p ≤ 0.001). After multivariable adjustment, PORT improved OS (adjusted hazard ratio 0.79, 95% confidence interval 0.70–0.89). In subgroup analysis, PORT provided benefit for certain histologic subtypes and all other patient groups except those with T1 tumors and undifferentiated/anaplastic tumor grades.

Conclusions

Our data suggests that PORT was associated with improved survival. Additionally, some subgroups may receive additional benefit and patients with small (T1), low-grade disease may be able to forgo PORT.

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