Proton radiation therapy for primary sphenoid sinus malignancies: Treatment outcome and prognostic factors

BACKGROUND: The purpose of this study was to determine treatment outcome and prognostic factors in patients with locally advanced primary sphenoid sinus malignancy treated with proton radiation therapy. METHODS: Between 1991 and 2005, 20 patients with primary sphenoid sinus malignancy received proton beam to a median dose of 76 Gray equivalent. RESULTS: With a median follow-up of 27 months, the 2-year local, regional, and freedom from distant metastasis rates were 86%, 86%, and 50%, respectively. The disease-free and overall-survival rates at 2 years were 31% and 53%, respectively. In multivariate analysis, oropharyngeal involvement (p = .005) and anterior cranial fossa invasion (p = .02) were predictive for poor disease-free survival rate. Brain invasion was predictive for decreased overall-survival rate (p = .05). CONCLUSIONS: Proton radiation therapy results in excellent local control in patients with advanced primary sphenoid sinus malignancy. Brain invasion, involvement of the oropharynx and anterior cranial fossa are important prognostic factors.