Postoperative Radiation Therapy for Parotid Pleomorphic Adenoma with Close or Positive Margins: Treatment Outcomes and Toxicities

Optimal management is not well-defined, and varying combinations of surgery (S), radiation therapy (RT) and chemotherapy (CT) have been reported. There have been substantial advances in surgery as well as radiation therapy, which may offer improved outcomes. We review the management approaches, long-term outcomes, and patterns of failure of patients treated at our institution to help define the optimal management for this rare malignancy. Materials/Methods: Fifteen patients with SNUC were treated from 19922012 at our institution, with pathology reviewed and confirmed. Demographic, treatment, and clinical data were collected from medical records. Patients underwent imaging evaluation with CT and/or MRI. Event outcomes were calculated from date of surgery to time of recurrence, death, or last follow-up. Survival statistics were calculated using the Kaplan-Meier and Cox Regression methods. Results: There were 10 male and 5 female patients with median age 49 years (range 22-82). Most patients had locally advanced T stage: T2 (n Z 2), T3 (n Z 5), and T4 (n Z 8). At diagnosis, 1 patient was clinically node positive and none had distant metastases. Treatment was as follows: 4 S + postoperative RT +/chemotherapy (CT); 3 preoperative chemoradiation (CRT) + S; 7 primary CRT; 1 RT alone. Nine had RT to primary site alone, and 6 had elective neck RT. Median dose was 69.5 Gy (range 50.4-70.2). Most received concurrent CT (n Z 12). Median follow up was 39 months (range 3-206). At time of analysis, 8 patients are alive, 6 have died and 1 is lost to follow up. KM projected 5-year OS and RFS-rates were 70% and 53%, respectively. Five patients recurred: 1 local, 1 local/neck, 1 neck, 1 distant, 1 local/neck/distant. Median time to recurrence was 7 months. On univariate analysis, there was no statistically significant impact of stage, use of surgery, use of chemotherapy, radiation dose, gender, or age on survival. A trend for improved survival with concurrent CRT was seen (p Z 0.097). Conclusions: SNUC is a highly aggressive malignancy associated with a high risk of disease recurrence, consistent with other series reported in the literature. There are some long term survivors who were treated with primary CRT or preoperative CRT followed by surgery. Early multimodality therapy is necessary for improved outcomes. The optimal timing and sequence of S, RT and CT should be further investigated. Author Disclosure: J.J. Liao: None. P. Jewell: None. U. Parvathaneni: None. G. Laramore: None. N. Polissar: None. W. Wong: None.