Radiotherapy

The mindset of many based on historical percepts is that radiotherapy has limited efficacy in the management of parotid malignancies. Even recently published data have suggested that adjunctive radiotherapy did not favorably affect prognosis related to recurrence.1 Retrospective studies are clearly of concern. Vastly improved imaging, dose sequencing, planning, and delivery systems during the past 5 years make older studies of questionable significance. Current wisdom suggests that, in the appropriate setting, radiotherapy does, in fact, reduce the rate of local recurrence.8 Further, for recurrent or inoperable malignant neoplasms, with or without prior irradiation, a neutron-based regimen has documented efficacy.9 Under these circumstances, neutrons have an approximately threefold improvement in survival at 2 years as compared with daily photon sequences. Acknowledged comorbidities have arisen years after neutron therapy, but recent improvements in planning and dosimetry should decrease these late sequelae. Photon sequencing remains controversial, but efficacy could reasonably be expected in epithelial-based malignancies. I currently recommend suggesting postoperative radiotherapy for all stage 3 and 4 malignant tumors. The inclusion of T2 tumors is dependent on histologic grade. For small high-grade malignancies with extension or adherence to the facial nerve, postoperative radiotherapy is individualized as decided by our tumor board.

More problematic is defining the role of radiotherapy for recurrent pleomorphic adenoma. Radiotherapy has been shown to decrease recurrence when administered after limited local excision with or without tumor spill and after surgery for recurrences. This led to a period of use for multifocal recurrence after reoperation. However, this form of management for initially benign disease is far from innocuous. Complications, including xerostomia, osteo-radionecrosis, and fibrosis, are recognized. Further, after a 20-year therapeutic interval, the incidence of carcinoma is increased if radiotherapy was used. A recent review of 126 cases of recurrent pleomorphic adenoma makes the case for surgery as the treatment modality of choice.10 In this study, the average time of follow-up was 14.5 years. Interestingly, tumor recurrence was 32.5% after the first reoperation, 7.1% after the second operation, and 1.6% after the third. If excision of the biopsy site accompanied a parotidectomy shortly after local excision had been performed, no tumor recurred. Importantly, after all procedures, total paralysis occurred in 5.5% and partial paralysis in 13.5% of cases. In my practice, I manage recurrent pleomorphic adenoma with repeated extirpation until such an option no longer exists, which is rare.

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