Postoperative radiation therapy for parotid pleomorphic adenoma with close or positive margins: treatment outcomes and toxicities

Aim: To evaluate the locoregional control and treatment toxicity of patients with pleomorphic adenoma after resection with close or positive margins followed by postoperative radiation therapy (PORT).

Patients and methods: Between 2002 and 2011, twenty-one patients underwent PORT at the Mount Sinai Beth Israel Medical Center for pleomorphic adenoma of the parotid with close or positive margins. Four out of the 21 patients (19%) had recurrent lesions. The median dose was 57.6 Gy (range 55.8-69.96) delivered at 1.8-2.12 Gy/fraction. Treatment and follow-up data were retrospectively analyzed for locoregional control as well as acute- and late-treatment toxicities. Actuarial survival analysis was also performed.

Results: Twelve women and 9 men with a median age of 46 (26-65) at PORT were included in this study. Eighty-one percent of the cohort had positive resection margins while 19% had close margins. At a median follow-up of 92 months, 19/21 patients (90%) had locoregional control. Two patients who failed had primary lesions which recurred locally, and initially had positive margins. The two recurrences occurred at 8 months and 12 months. Acute Radiation Therapy Oncology Group (RTOG) grade 1 and 2 toxicities were experienced by 11 (52%) and 4 (19%) patients, respectively, while 2 (10%) experienced late RTOG grade 1 toxicities. No patients experienced any grade 2-4 late toxicities. Actuarial survival was 100%.

Conclusion: PORT for patients with pleomorphic adenoma of the parotid gland after resection with close or positive margins results in excellent locoregional control and low treatment-related morbidity.