Radiation-induced salivary gland tumors: A report of 18 cases and a review of the literature

PURPOSE The purpose of this study was to examine the relationship between radiation exposure and subsequent development of salivary gland tumors (SGTs). MATERIALS AND METHODS Eighteen patients with SGTs as second cancers after head and neck irradiation were identified from chart review of institutional databases of 3025 patients with SGTs evaluated between 1986 and 2001. RESULTS The median age at the time of initial radiation therapy was 22 years (range, 5-74 years). The median age of the group at the time of their diagnosis of a SGT was 54 years (range, 21-79 years). The median interval between radiation exposure and diagnosis of the SGT was 21 gears (range, 4-64 years). The most common initial diagnosis for which patients received radiation therapy was Hodgkin's disease. Histology of the secondary SGT was varied, but most were malignant (N = 15), and mucoepidermoid carcinoma was the most common histology (N = 9). CONCLUSION There is an association between radiation exposure and the risk of developing an SGT. There was a wide range in the dose of radiation and the age at exposure, suggesting that exposure to head and neck radiation at any age and dose may increase the risk for SGT. This series also suggests an increased risk for developing malignant (versus benign) SGT after raditation exposure.