Hearing Loss and Middle Ear Effusion in Nasopharyngeal Carcinoma Following Radiotherapy: Dose–Response Relationship and Normal Tissue Complication Probability Modeling

<b>Introduction</b> Radiotherapy is the primary treatment for nasopharyngeal carcinoma. Radiation exposure to the cochlea and middle ear can cause hearing loss. <b>Objective</b> To develop a multivariable normal tissue complication probability (NTCP) model to predict the risk of hearing impairment in nasopharyngeal cancer patients based on clinical and radiation dosimetry features and to identify the key factors associated with hearing loss. <b>Methods</b> A retrospective review of 229 patients was conducted. We recorded the audiometry and presence of middle ear effusion (MEE) and compared findings before and after therapy. The factors included age, gender, signs and symptoms at presentation, tumor staging, prescribed dose at the tumor and high-risk nodal region, cochlea, and concurrent chemotherapy treatment. The model was formulated using multivariate logistic regression. <b>Results</b> Age of more than 50 years, high primary staging, and dose at the cochlea > 43 Gy were major risk factors for sensorineural hearing loss. The final NTCP model for hearing loss comprised age and cochlea dose with an area under the curve (AUC) of 0.644; the predicted risk ranged from 15.84 to 44.52%. Locally advanced disease and cochlea dose greater than 44 Gy were risk factors for MEE; the predicted risk ranged from 20.42 to 51.99%. <b>Conclusion</b> Age over 50, T stages 3 and 4, and > 43 Gy dose to the cochlea were significantly associated with an increased risk of sensorineural hearing loss and MEE. The developed NTCP model provides information to predict these risks, aiding in treatment planning and decision-making to avoid complications.