Analysis of patients with parotid recurrence after parotid-sparing IMRT for nasopharyngeal carcinoma: case series and review of the literature.

Abstract

Intensity-modulated radiotherapy (IMRT) is the standard treatment approach for nasopharyngeal cancer (NPC). IMRT enables effective sparing of the parotid glands and reduces the risk of xerostomia, acommon complication of head and neck irradiation. Nevertheless, it is essential to determine whether the parotid-sparing IMRT (ps-IMRT) technique yields increased intra-/periparotid recurrence rates, which constitutes the main purpose of this study. Patients with adiagnosis of NPC that received definitive chemoradiotherapy/radiotherapy (CRT/RT) between 1991 and 2021 were evaluated retrospectively. Patients with intra-/periparotid recurrence were detected and prognostic factors for recurrence were sought. Atotal of 746 patients were evaluated. Two-dimensional (2D)-RT was applied to 541, 3D conformal RT (3D-CRT) to 10, and ps-IMRT to 195 patients. After amedian 85-month follow-up, one (0.18%) patient who received 2D-RT and four (2%) patients who received ps-IMRT experienced an intra-/periparotid recurrence. The median time to intra-/periparotid recurrence was 11.9 months. All patients had been diagnosed with ametastatic lymph node > 2 cm at levelII of the ipsilateral neck. In addition, all recurrences occurred on the same side as the positive neck at the time of diagnosis. The 3‑year overall survival, locoregional recurrence-free survival, and distant metastasis-free survival rates were 80%, 40%, and 60%, respectively. Intra-/periparotid recurrence is extremely rare in NPC. However, it is still possible to identify and characterize particular risk factors, which include ametastatic lymph node at levelII, particularly > 2 cm, and multinodal disease at the time of diagnosis.