Introduction
Nasopharyngeal carcinoma (NPC) is the most common type of tumor originating in the epithelium of the nasopharynx and a distinct tumor of head and neck region which is primarily treated with external beam radiation therapy, with or without concurrent cisplatin chemotherapy.1,2 External beam radiation to the head and neck region is notorious for its otologic complications including external otitis, otitis media, sensorineural hearing loss (SNHL) and osteoradionecrosis of the temporal bone.3,4 Post irradiation middle ear effusion (MEE), is associated with conductive hearing loss. If not identified and managed properly, it may progress to full atelectasis of the ear drum associated ossicular bone erosion, hearing loss deterioration and cholesteatoma.5,6 Therefore, evaluation of NPC patients for the presence of MEE is mandatory.
In the late 1990’s new radiation modalities were introduced to decrease the radio-toxicity related to the radiation therapy (RT), one of which is intensity-modulated radiotherapy (IMRT).7,8 IMRT is superior to the traditional 2D radiation due to its three-dimensional properties which allow a more precise planning of the irradiated tumor volume, sparing non-involved regions. As such, in patients with NPC it may allow reducing the otologic complications.9,10 The main structures associated with normal middle ear function are the Eustachian tube (ET), the Levator veli-palatini (LVP) and Tensor veli-palatine (TVP) muscles which function as the ET dilators, and are therefore crucial for its normal function and patency.
The primary objective of this study was to perform a comprehensive analysis of patient, tumor and treatment parameters as risk factors for post radiation MEE in NPC patients. Specifically, irradiation parameters of the middle ear, ET, TVP and LVP regions were investigated as well as potential contributors.