Objective: To examine the effect of adjuvant radiation therapy (RT) on survival of high-grade and/or locally advanced malignant major salivary gland tumors (MMSGT). Patients: The study population comprised 2170 patients with high-grade (poorly differentiated or undifferentiated) and/or locally advanced MMSGT (T3/4 or Nϩ). Main Outcome Measures: The Surveillance, Epidemiology, and End Results registry was used to obtained data for all patients 20 years or older who underwent surgery for

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... e and/or locally advanced nonmetastatic MMSGT between 1988 and 2005. Univariate and multivariable regression analyses were performed to identify factors associated with improved survival. Results: Seventy-two percent of patients received adjuvant RT, while 28% underwent surgery alone. Patients receiving adjuvant RT were younger and had higher T and N categories and grade. Multivariable analysis re-vealed significantly improved survival with adjuvant RT (HR for mortality, 0.76; 95% CI, 0.65-0.89; P Ͻ .001). Other factors associated with improved survival included younger age at diagnosis, less than radical surgery, certain histologic subtypes, lower grade, and lower T and N categories. Subset analyses found significantly improved survival with adjuvant RT among patients with both high-grade and locally advanced disease (PϽ.001), involvement of the parotid gland (P = .002), or squamous cell carcinoma (P =.004), with a survival benefit seen among patients with adenocarcinoma that did not reach significance (P=.06). Conclusions: Adjuvant RT is associated with improved survival for high-grade and/or locally advanced MMSGT based on analysis of this large, population-based database. Further prospective studies are warranted to examine the role of RT in the management of this disease.