Radiation Therapy in the Treatment of Minor Salivary Gland Tumors

Abstract

Minor salivary gland cancers are rare and account for roughly 2% to 3% of all head and neck tumors. This is a retrospective review in a modern cohort of patients treated for this rare cancer with surgery and adjuvant radiation therapy. Between February 1990 and December 2010, 98 patients with cancer of the minor salivary glands were identified and treated at a single institution. The median radiation dose was 63 Gy. Outcomes assessed included local control (LC), locoregional control (LRC), and overall survival (OS). Toxicity was graded using the Common Terminology Criteria for Adverse Events, version 3.0. Competing-risk analysis using the Gray test was performed, with death as the competing risk. OS was calculated by the Kaplan-Meier method. With a median follow-up of 7.3 years, the 5- and 10-year LC and LRC rates were 87.9% and 83%, and 80.5% and 73.7%, respectively. Higher T stage and adenocarcinoma histology were the significant negative prognostic factors for both LC and LRC. Freedom from distant metastasis at 5 and 10 years were 83% and 63%, respectively. The median OS was 19.6 years. Overall, no grade 4 or 5 toxicities occurred, and 20% of the cohort experienced an acute grade 3 toxicity, and 6% with a grade 3 late toxicity. In a modern cohort treated with surgery and radiotherapy, excellent outcomes can be achieved with lower toxicity rates compared with older published series.