Sensori-neural hearing loss after radiotherapy for nasopharyngeal carcinoma:: individualized risk estimation

Background and purpose: Sensori-neural hearing loss (SNHL) is a common complication to radiation therapy in the upper head and neck region. In this study. we estimated the dose response relationship for SNHL with adjustment for pre-therapeutic risk factors. Patients and methods: The pre- and post-therapeutic hearing levels were recorded in a previously published study of 20 patients receiving radiotherapy for nasopharyngeal carcinoma. In the present study, the dose to the inner ear of these patients was estimated with a computed tomography (CT) based treatment planning system. CT data from a 'proxy patient' were used for patients with no available CT scan. SNHL was analyzed as a function of radiation dose and potential risk factors were tested. Results: The incidence of SNHL increased significantly with increasing dose to the cochlea. Increasing patient's age, and decreasing pre-therapeutic hearing level were statistically significantly associated with an increased risk of SNHL. A nomogram is presented for estimating individualized dose constraints of potential use in treatment planning. Conclusions: The inner ear is a critical structure in patients with nasopharyngeal carcinoma and the close to the inner ear should be carefully considered when planning radiation treatment in this region. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.