1

Introduction

Pleomorphic adenomas are the most common benign tumor of the salivary glands, accounting for 75% to 80% of benign parotid gland neoplasms . Demographic variability is reported geographically, but pleomorphic adenomas typically occur in women between the ages of 30 and 60 years . Smoking does not play a role in this disease . These tumors present as slowly enlarging painless masses that can lead to significant morbidity and mortality if untreated . Transformation to carcinoma ex pleomorphic occurs in 3% to 4% of patients, and the tumor can metastasize and contribute to mortality . Close proximity of the facial nerve to the parotid gland can impede complete resection, but optimal treatment with superficial or total parotidectomy results in local control exceeding 95% . For patients with gross residual disease due to the disease site, positive margins, or multifocal recurrence, postoperative radiotherapy (RT) can provide long-term local control with minimal cosmetic and functional impairments . The purpose of this study was to update the outcomes of patients treated with RT for pleomorphic adenoma at the University of Florida .

2

Materials and methods

Between 1970 and 2008, 25 patients with histologically confirmed pleomorphic adenoma were treated with RT alone (2 patients) or RT and surgery (23 patients) at the University of Florida. Patients eligible for this study were observed at a minimum follow-up of 2 years. Medical records were retrospectively reviewed under an institutional review board–approved protocol. Complications were assessed using Common Terminology Criteria for Adverse Events, version 4.0 .

Table 1 depicts individual patient, tumor, and treatment characteristics. Twelve patients were men, and 13 were women. Twenty-two were white, and 3 were African American. The median age at diagnosis was 45 years (range, 32–77 years). Eight patients presented with de novo tumors, whereas 10, 5, 1, and 1 patients had 1, 2, 3, or 4 surgical resections for recurrent disease, respectively. Primary tumor sites were as follows: parotid (n = 19), hard palate (n = 3), nasopharynx (n = 1), and parapharyngeal space (n = 2). The extent of surgical resection was distributed as follows: superficial parotidectomy, 12; total parotidectomy, 4; enucleation, 1; and resection sites other than parotid gland, 6. Five patients had equivocal margins, 11 had positive margins, and 7 had gross disease after surgical resection. Two patients had no surgery. The median tumor size was 29 mm (range, 5–70 mm). Five patients had tumors of unspecified size.

The median time interval between surgery for the most recent recurrence and RT was 48 days (range, 14–559 days). Seventeen patients received once-daily external-beam RT to a median total dose of 64.8 Gy (range, 56.5–70 Gy) and a median dose per fraction of 1.8 Gy. Seven patients were treated with twice-daily external-beam RT to a median dose of 74.4 Gy (range, 62.9–74.4 Gy) and a median dose per fraction of 1.2 Gy. One patient was treated with brachytherapy. Twenty patients were treated with continuous-course RT, and 3 patients received planned split-course radiation, a technique only used between 1970 and 1974. Two patients were treated with RT alone, including 1 patient with a nasopharyngeal tumor and 1 with a tumor of the hard palate.

Posttreatment surveillance with periodic physical examination, computed tomography, or magnetic resonance imaging was performed with decreasing frequency with prolonged survival. The median follow-up for the entire cohort was 10.5 years. (range, 1.8–34.9 years). The median follow-up for living patients was 15.7 years (range, 5.2–34.9 years). No patients were lost to follow-up.