Long-term outcome of patients treated by radiation therapy alone for salivary gland carcinomas

Purpose: To review a single-institution experience with the management of salivary gland cancers treated by radiation alone. Methods and Materials: Between 1960 and 2004, 45 patients with newly diagnosed salivary gland carcinomas were treated with definitive radiation to a median dose of 66 Gy (range, 57-74 Gy). Distribution of T-stage was: 24% T1, 18% T2, 31% T3, and 27% T4. Histology was: 14 mucoepidermoid (31%), 10 adenocarcinoma (22%), 8 adenoid cystic (18%), 4 undifferentiated (9%), 4 acinic (9%), 2 malignant mixed (4%), 2 squamous (4%), and 1 salivary duct carcinoma (2%). No patient had clinical or pathologic evidence of lymph node disease. Median follow-up was 101 months (range, 3-285 months). Results: The 5-year and 10-year rate estimates of local control were 70% and 57%, respectively. A Cox proportional hazard model identified T3-4 disease (p = 0.004) and radiation dose lower than 66 Gy (p = 0.001) as independent predictors of local recurrence. The 10-year overall survival and distant metastasis-free rates were 46% and 67%, respectively. Conclusion: Radiation therapy alone is a reasonable alternative to surgery in the definitive management of salivary gland cancers and results in long-term survival in a significant proportion of patients. Radiation dose in excess of 66 Gy is recommended.