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


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 dose to the inner ear should be carefully considered when planning radiation treatment in this region.
Honoré
Henriette B
HB
Department of Medical Physics, Aarhus University Hospital, Nørrebrogade 44, Building 5, DK-8000 Aarhus C, Denmark.
Bentzen
Søren M
SM
Møller
Kitty
K
Grau
Cai
C
D000328:Adult; D000368:Aged; D001933:Brain Stem / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D007758:Ear, Inner / Q000528:radiation effects*; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010306:Parotid Gland / Q000528:radiation effects; D010347:Patient Care Planning; D010902:Pituitary Gland / Q000528:radiation effects; D011832:Radiation Injuries / Q000209:etiology*; D018570:Risk Assessment