Distant metastasis is a critical mode of failure for patients with localized major salivary gland tumors treated with surgery and radiation

Objectives: Excellent local-regional control can be achieved for major salivary gland tumors treated with surgery and postoperative radiotherapy. We evaluated the cumulative incidence and predictors of distant metastasis in high-risk major salivary gland tumors. Methods: Between 1990 and 2011, 200 patients with major salivary gland tumors received postoperative radiotherapy at our center. The patients' median age was 60 years. Patients had primary tumors of the parotid gland (84 %), submandibular (16 %), and one sublingual gland. Among the patients, 34 % had T3-T4 tumors, 32 % had nodal involvement. Other high-risk features included close/positive margins and high-grade tumors. The median RT dose was 63 Gy. Results: With a median follow-up of 50 months, the 5-year local control and regional control were 88 and 94 %, respectively. The 5-year freedom from distant metastasis was 73 %. The median overall survival was 14.6 years corresponding to a 5- and 10-year overall survival of 77 and 59 %, respectively. T category and nodal involvement were independent predictors of distant metastasis. Nodal involvement was also an independent predictor of overall survival. Conclusions: Distant relapse was the predominant mode of failure despite excellent local-regional control in high-risk major salivary gland tumors. Both advanced T category and nodal involvement were independent predictors of distant metastasis. More effective systemic therapy is needed to combat distant relapse.